The link between corticosteroid exposure and rosacea is not itself new. Dermatologists have known for decades that topical steroids applied directly to the face can trigger a condition known as steroid-induced rosacea, in which the very drug meant to calm inflammation ends up provoking redness, burning and visible blood vessels. What has been far less studied is whether the same risk applies when the steroid is sprayed into the nose rather than rubbed onto the cheeks. Intranasal fluticasone propionate is a mainstay of treatment for allergic rhinitis and chronic sinusitis, available in many countries without a prescription, which means millions of users may never discuss the drug with a physician who could monitor its skin effects.

To probe that question, the research team, led by Taylor Merkle and senior author Erum N. Ilyas, designed a cross-sectional survey of twenty-one questions built around a validated diagnostic tool called Rosascreen. Developed and evaluated in 2016, Rosascreen asks about the cardinal cutaneous signs of rosacea: facial redness, visible facial blood vessels, eyelid irritation, facial warmth or a stinging and burning sensation, thickened skin on the nose, and pimples. Participants were also asked about how often they used intranasal fluticasone propionate and for how long, allowing the researchers to separate acute exposure, defined as less than three months, from chronic and frequent patterns of use. The study received approval from the Drexel University College of Medicine Institutional Review Board, and participation was voluntary, anonymous and confidential, with no compensation offered.

The analysis ultimately drew on 155 valid survey responses. Using simple statistics, chi-square tests and odds ratios derived from ordinal logistic regression models, the investigators compared symptom presence across categories of use frequency and duration. The most striking single finding concerned facial redness, which was the only individual symptom significantly associated with both how often and how long people used the spray, with chi-square values of 6.05 and 14.14 and p-values of 0.049 and 0.0009 respectively. In other words, the more often people used the medication and the longer they stayed on it, the more likely they were to report the persistent flushing and redness that characterizes rosacea.

Perhaps counterintuitively, the heaviest symptom burden was seen in the newest users. People who had been using the spray for less than three months showed the highest odds of increased symptom burden, with an odds ratio of 4.06 and a 95 percent confidence interval of 1.52 to 10.85, reaching statistical significance at p equals 0.005. Chronic users did not escape the association either: long-term use remained significantly linked to a higher symptom burden, with an odds ratio of 2.05 and a confidence interval of 1.09 to 3.87 at p equals 0.026. Frequent users similarly faced elevated odds, at an odds ratio of 2.44 with a confidence interval of 1.28 to 4.66 and p equals 0.007. Taken together, the numbers suggest that the relationship between intranasal steroid exposure and rosacea-like symptoms tracks both frequency and duration of use.

The proposed biological explanation hinges on the peculiar way corticosteroids interact with blood vessels in the skin. Glucocorticoids are potent vasoconstrictors, and when they are first introduced they can transiently reduce facial inflammation and even narrow superficial blood vessels, which may initially feel or look like an improvement. The trouble begins when doses are reduced or used inconsistently. Rebound vascular reactivity can follow, a phenomenon in which the vessels dilate beyond their baseline state, producing the flushing, burning and telangiectasia that closely mimic classic steroid-induced rosacea. For intranasal users, the drug is absorbed locally in the nasal mucosa, which sits in close anatomical proximity to the facial vasculature, and some systemic and regional exposure is plausible, although the exact distribution of drug effect to facial skin remains to be worked out in controlled studies.

The history of this question stretches back further than many might expect. A case report published in 1999 in the International Journal of Dermatology described rosacea induced by beclomethasone dipropionate nasal spray, an earlier generation intranasal steroid, suggesting that the phenomenon is not unique to fluticasone. A broader systematic review of steroid-induced rosacea published in 2025 consolidated the evidence that topical corticosteroid exposure can reliably provoke the condition, while reviews of intranasal steroid safety have generally focused on systemic concerns such as effects on growth in children, adrenal suppression and local nasal side effects rather than facial skin outcomes. The Drexel study effectively fills a gap between these two literatures, applying dermatological screening tools to a population usually studied only for respiratory symptoms.

The authors are careful to spell out the limitations of their approach, and they are considerable. The survey used convenience sampling rather than a representative population frame, all symptom data were self-reported rather than confirmed by clinical examination, and the study could not control for demographic and clinical confounders. Crucially, the design could not assess underlying conditions such as rhinitis or sinusitis themselves, which might independently correlate with facial flushing or vascular reactivity. Cross-sectional surveys also cannot establish causation; it is possible, for example, that people prone to rosacea experience more nasal symptoms and therefore use more steroid spray, reversing the direction of the association. The authors explicitly call for controlled studies to clarify the causal effects of intranasal steroids on cutaneous outcomes before firm clinical guidance can be written.

Even with those caveats, the practical message for clinicians is straightforward. The researchers highlight the importance of asking patients who present with unexplained facial redness about their use of over-the-counter intranasal steroids. Because these products sit on pharmacy shelves and are marketed for seasonal allergies, patients often do not think of them as medications worth mentioning, and a busy clinician may not think to ask. A simple question about nasal spray use could spare patients a cycle of escalating symptoms and misdirected treatments, including the ironic prescription of additional topical steroids that would only worsen steroid-induced disease.

For the public, the study is less a reason to abandon an effective allergy treatment than a reminder that even familiar over-the-counter drugs can have consequences beyond their intended target. Intranasal corticosteroids remain among the most effective and widely recommended therapies for allergic rhinitis and chronic sinusitis, and the associations reported here are preliminary and observational. But the work underscores a broader theme in modern pharmacology: as medications migrate from prescription pads to self-service shelves, the surveillance of their side effects increasingly falls to researchers willing to ask unusual questions, in this case connecting an ENT remedy to a chronic inflammatory skin disease. Future controlled trials will determine whether the redness in the mirror is truly a rebound from the spray, but for now, users of fluticasone nasal spray who notice new facial redness have good reason to mention it to their doctor.

Subject of Research: Association between over-the-counter intranasal corticosteroid use and rosacea-like facial symptoms

Article Title: Rosacea-like findings associated with over-the-counter intranasal corticosteroid use: a survey study

Article References: Merkle, T., Curley, C., Rezaee, R., Cook, H., Wambold, D., & Ilyas, E. N. (2026). Rosacea-like findings associated with over-the-counter intranasal corticosteroid use: a survey study. Archives of Dermatological Research, 318(1), Article 406. https://doi.org/10.1007/s00403-026-04899-8

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04899-8

Keywords: rosacea, intranasal corticosteroids, fluticasone propionate, facial redness, allergic rhinitis, chronic sinusitis, steroid-induced rosacea, Rosascreen, dermatology, cross-sectional survey, over-the-counter medication, vascular reactivity

The research team, led by investigators at Northwestern University Feinberg School of Medicine including dermatologist Peter Lio, drew on data from the National Institutes of Health’s All of Us Research Program, a massive biomedical database that links participant surveys to electronic health records. Because the program collects detailed demographic information alongside longitudinal clinical data, it allowed the researchers to do something previous studies of the rosacea-gut connection rarely could: measure, patient by patient, the interval between the two diagnoses and test whether that interval differed systematically across population groups.

The statistical machinery behind the study was chosen with care. When the team examined the distribution of time differences between diagnoses, formal tests for normality and equal variance, specifically Shapiro-Wilk and Levene’s tests, indicated that the data violated the assumptions required for parametric statistics. The researchers therefore turned to non-parametric methods: Wilcoxon signed-rank tests to assess whether, within each demographic stratum, the median time difference between the IBS and rosacea diagnosis dates shifted significantly away from zero, and Kruskal-Wallis tests to compare those shifts between groups defined by race and ethnicity, education, income, gender, and age.

The headline result is a consistent directional skew. The median time difference, calculated as the IBS diagnosis date minus the rosacea diagnosis date, was negative in every demographic group the team examined, ranging from about 0.09 years to 2.03 years before the rosacea diagnosis. In plain terms, across every stratum of the population studied, the typical patient had their bowel syndrome documented before their facial flushing earned a name. Wilcoxon signed-rank tests confirmed that these within-group median shifts were statistically significant in several strata, particularly those with the largest sample sizes, where the tests have the most power to detect real asymmetry.

Yet the study’s second major finding is just as important as the first: demographics do not explain the pattern. When the researchers built a logistic regression model to predict which condition came first using race and ethnicity, education, income, gender, and age, the model achieved only 52.6 percent accuracy, barely better than a coin flip, with an area under the curve of 0.52. Kruskal-Wallis comparisons between demographic groups were uniformly non-significant, with p-values of 0.98 for race and ethnicity, 0.83 for education, 0.40 for income, 0.52 for gender, and 0.14 for age. Whatever drives the gut-before-skin sequence, it does not appear to respect the usual social and demographic fault lines.

To understand why this temporal ordering matters, it helps to zoom in on the biology that has energized the gut-skin axis field in recent years. The gut and the skin are both barrier organs, both heavily populated by immune cells, and both colonized by microbial communities that communicate with the host immune system. Reviews of the gut-skin axis have described how intestinal dysbiosis, an imbalance in gut microbial composition, can increase intestinal permeability, promote systemic inflammation, and modulate immune signaling in ways that plausibly reach the skin. In rosacea specifically, studies have documented activation of Th1 and Th17 inflammatory pathways in lesional skin, and systematic reviews have linked the condition to alterations in both cutaneous and gastrointestinal microbiomes.

The connection between rosacea and the gut is not new to dermatologists. Population-based cohort research from Denmark published in 2017 found that people with rosacea had elevated rates of several gastrointestinal disorders, including celiac disease, Crohn’s disease, ulcerative colitis, and irritable bowel syndrome. More recently, a study using the Korean National Health Insurance Service cohort examined whether rosacea might raise the risk of subsequently developing IBS, and bi-directional Mendelian randomization analyses have probed whether inflammatory bowel disease and rosacea share causal links through genetic instruments. Small intestinal bacterial overgrowth has also been reported at elevated rates in rosacea patients, and some trials have explored whether targeting the gut microbiome can calm the skin. What most of this earlier work lacked, however, was a direct measurement of onset order within the same individuals.

That is precisely the gap the new study fills, and the direction of the skew, IBS first in a majority of cases, is at least compatible with a model in which chronic gut inflammation or microbial disturbance contributes to the later emergence of cutaneous disease. Chronic gut inflammation and dysbiosis in IBS have been implicated in other inflammatory skin conditions, including atopic dermatitis, and neurohormonal-immune dysregulation along the skin-gut-brain axis has been proposed as a shared pathway in rosacea. If gut-driven systemic inflammation primes the skin’s vasculature and immune defenses, one might expect bowel symptoms to precede facial ones, on average, which is what the data show at the population level.

But the authors are careful, and rightly so, to keep the interpretation within strict limits. The dataset records the date a diagnosis was documented, not the date symptoms actually began. A patient may have endured years of abdominal pain before a clinician finally wrote down an IBS code, or may have had visible facial redness long before anyone called it rosacea. Diagnostic lag, healthcare access, and coding practices could all distort the apparent sequence. The study is also cross-sectional in design, meaning it captures a snapshot of the timing relationship rather than following patients forward in time, and it cannot establish that IBS causes rosacea or that any shared mechanism exists at all. The researchers themselves emphasize that the findings are descriptive and that prospective studies incorporating clinical and lifestyle variables are needed before any gut microbiome-mediated link can be properly evaluated.

Even with those caveats, the study offers a genuinely useful piece of the puzzle. It demonstrates, in a large and demographically diverse cohort, that the association between IBS and rosacea is not a random collision of two common conditions but a temporally structured one, with a reproducible direction that holds across race, ethnicity, education, income, gender, and age. It also delivers a humbling lesson about prediction: population-level patterns can be real and robust while remaining nearly useless for forecasting what will happen in any individual patient. For clinicians, the practical takeaway is one of heightened awareness, since a patient presenting with one of these conditions may warrant attention to the other. For researchers, the study provides a temporal scaffold on which mechanistic hypotheses about microbial signaling, immune trafficking, and neurovascular inflammation can now be tested with prospective designs. The gut-skin axis has been celebrated in headlines for years; studies like this one, modest in size but precise in method, are how the field moves from slogan to science.

Subject of Research: The temporal onset relationship between irritable bowel syndrome and rosacea within the gut-skin axis

Article Title: Temporal relationship between irritable bowel syndrome (IBS) and rosacea: an analysis of onset timing

Article References: Marzouk, S., Saleeb, J., Muttar, S., Alkhalili, S., Alsheikh, A., Nasari, A., Hassan, T., Issa, R., Hassan, O., & Lio, P. (2026). Temporal relationship between irritable bowel syndrome (IBS) and rosacea: an analysis of onset timing. Archives of Dermatological Research, 318(1), Article 524. https://doi.org/10.1007/s00403-026-05003-w

Image Credits: AI Generated

DOI: 10.1007/s00403-026-05003-w

Keywords: irritable bowel syndrome, rosacea, gut-skin axis, gut microbiome, onset timing, All of Us Research Program, dermatology, gastroenterology, chronic inflammation, dysbiosis, cross-sectional study, electronic health records

The NIH All of Us program is one of the most ambitious biomedical data collection efforts ever attempted. Launched as part of a national push toward precision medicine, it aims to gather health, lifestyle and environmental information from more than a million participants across the United States, with deliberate oversampling of communities that have historically been underrepresented in medical research. Participants contribute survey responses covering diet, physical activity, smoking and alcohol use, alongside electronic health record data, physical measurements and, for many, genomic information. For dermatology researchers, this represents a rare opportunity: most rosacea studies are conducted in single clinics with hundreds of patients, while a database of this scale allows investigators to examine associations across tens of thousands of individuals drawn from wildly different backgrounds.

Rosacea itself is far more than simple facial redness. Clinicians recognize several overlapping subtypes, including erythematotelangiectatic rosacea, marked by persistent flushing and visible blood vessels; papulopustular rosacea, which produces acne-like bumps; phymatous rosacea, which can cause thickening of the skin, most famously around the nose; and ocular rosacea, which affects the eyes and eyelids. The condition follows a relapsing-remitting course, flaring in response to triggers that vary from person to person. Common culprits include sun exposure, heat, emotional stress, spicy foods, alcohol and hot beverages. Because the disease is so heterogeneous, large-scale data is essential for separating genuine risk factors from anecdotal associations that have accumulated over decades of clinical observation.

The pathophysiology of rosacea involves a complex interplay of innate immune dysregulation, neurovascular abnormalities and disruption of the skin’s microbial and physical barriers. Research over the past two decades has implicated elevated levels of antimicrobial peptides such as cathelicidin, heightened reactivity of transient receptor potential channels that sense heat and irritation, and an altered relationship with Demodex mites that colonize facial hair follicles. Chronic inflammation in rosacea has also been linked, in other studies, to systemic comorbidities including gastrointestinal disorders, cardiovascular disease and metabolic conditions, which is precisely the kind of association that a database as broad as All of Us is positioned to interrogate. Understanding whether rosacea is purely a skin disease or a visible marker of broader inflammatory states remains an open and clinically important question.

By analyzing lifestyle and dietary variables alongside rosacea status, the Northwestern team’s approach reflects a growing recognition that the social determinants of health, the conditions in which people live, work and eat, shape dermatologic outcomes in ways that prescriptions alone cannot address. The concept, articulated in influential public health literature, holds that researchers must consider the causes of the causes. For rosacea, this could mean examining how obesity, smoking status, alcohol consumption, diet quality and physical activity correlate with disease presence and severity across a diverse population. It could also mean investigating whether treatment patterns differ systematically by demographic group, a question with direct implications for health equity in dermatology.

Treatment for rosacea currently spans a layered arsenal. Topical agents such as metronidazole, azelaic acid and ivermectin target the inflammatory and mite-related components of the disease, while brimonidine and oxymetazoline constrict dilated facial blood vessels to reduce persistent redness. Oral antibiotics, particularly low-dose doxycycline, remain a mainstay for moderate to severe cases, and isotretinoin is occasionally used off-label for refractory disease. Laser and intense pulsed light therapies address the vascular changes that medications cannot fully reverse. Skincare routines built around gentle cleansing and barrier repair are considered foundational. Yet adherence varies enormously, and many patients cycle through multiple therapies before finding a regimen that controls their flares. Mapping real-world treatment patterns across a large cohort could reveal gaps between guideline recommendations and what patients actually receive.

The All of Us database is particularly valuable for this kind of research because of its demographic breadth. Traditional rosacea studies have often focused on fair-skinned populations of European descent, partly because the condition is easiest to diagnose visually in lighter skin. In skin of color, erythema can be subtle or absent, and rosacea is frequently misdiagnosed or overlooked, contributing to delays in treatment. A dataset that deliberately includes diverse racial and ethnic groups offers the chance to characterize how rosacea presents, and how it is managed, across the full spectrum of skin tones. The authors’ affiliation with related research subjects including race and ethnicity, obesity, risk factors and nutrition suggests the analysis was structured around exactly these dimensions.

As with any database study, the methodology carries inherent constraints that readers should keep in mind. All of Us relies substantially on participant-reported survey data and electronic health records, both of which are subject to misclassification: rosacea diagnoses may be inconsistently coded, and dietary recall is notoriously imprecise. Observational associations drawn from such data can identify correlations but cannot by themselves establish causation, and unmeasured confounders may influence any observed relationships. The authors note that no new datasets were generated or analyzed within the current study, indicating that the work functions as a secondary analysis of existing program data. Short reports of this kind are often best understood as hypothesis-generating contributions that lay groundwork for more targeted prospective studies rather than as definitive answers.

Nevertheless, the significance of the approach is hard to overstate. Dermatology has historically lagged behind other medical specialties in leveraging large-scale real-world data, in part because skin disease is so visually heterogeneous and because many conditions are managed outside hospital record systems. Studies that mine national biobanks for dermatologic signals are helping to close that gap, and rosacea, with its tangled mix of triggers, comorbidities and treatment options, is an ideal candidate for this kind of investigation. If lifestyle and dietary factors can be more firmly linked to disease activity, clinicians may one day pair pharmacologic treatment with concrete behavioral guidance, much as they now do for acne or psoriasis.

For the millions of people who live with rosacea, research of this kind carries practical hope. The condition affects quality of life out of proportion to its medical severity, with documented impacts on self-esteem, social interaction and even employment in customer-facing roles. Flares are unpredictable, triggers are personal, and the emotional burden of a visibly inflamed face is easy to underestimate. A rigorous, population-scale accounting of which habits, foods and treatments actually matter, grounded in a dataset built to reflect the diversity of the American public, moves the field closer to personalized management strategies. The Northwestern team’s analysis, published as volume 318, article 433 of the Archives of Dermatological Research, is a step toward that future, and it signals that chronic skin disease is finally getting the big-data attention it deserves.

Subject of Research: Population-scale analysis of rosacea risk factors, lifestyle and dietary associations, and treatment patterns using the NIH All of Us database

Article Title: Rosacea and associated factors: a comprehensive analysis of lifestyle, dietary, and treatment patterns using the NIH All of Us database

Article References: Marzouk, S., Musabji, A., Issa, R., Saleeb, J., Hassan, O., Alkhalili, S., Hassan, T., Muttar, S., & Lio, P. (2026). Rosacea and associated factors: a comprehensive analysis of lifestyle, dietary, and treatment patterns using the NIH All of Us database. Archives of Dermatological Research, 318(1), Article 433. https://doi.org/10.1007/s00403-026-04952-6

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04952-6

Keywords: rosacea, NIH All of Us, dermatology, skin disease, lifestyle factors, diet, treatment patterns, inflammation, health equity, population health, chronic skin condition, precision medicine

The study is a retrospective chart review, a design in which researchers go back through patient records to check whether a particular data-mining strategy matches clinical reality. In this case, the team examined how well different approaches to using the International Classification of Diseases, 10th Revision, better known as ICD-10, performed at distinguishing true rosacea cases from lookalike conditions. Billing codes are assigned for administrative reasons, not research purposes, and clinicians may use a code for a suspected diagnosis, a rule-out, or even a billing workaround. That gap between what a code says and what a patient actually has is precisely the kind of hidden error that can quietly poison large-scale studies.

The stakes are higher than they might first appear. A recent worldwide epidemiological study cited by the authors estimated that acne and rosacea together affect enormous numbers of people across the globe, making rosacea one of the most prevalent reasons patients seek dermatological care. The condition typically produces facial flushing, persistent redness, visible blood vessels, and in some cases acne-like bumps or thickened skin around the nose. Beyond the physical symptoms, rosacea is associated with significant psychological burden, ocular complications, and, when left untreated, progressive changes that are difficult to reverse. Understanding its true prevalence, treatment patterns, and long-term outcomes depends entirely on being able to count the right patients.

Electronic health records have transformed dermatology research by offering access to millions of patients whose care would otherwise be invisible to scientists. But as Mostaghimi and Noe argued in a widely discussed 2021 paper on the challenges of big data in dermatology, the sheer scale of these datasets can create a false sense of confidence. Garbage in, garbage out remains the governing law of computational research. If a cohort defined by billing codes contains even a modest proportion of misclassified patients, effect sizes shrink, spurious associations emerge, and conclusions about drug safety or disease trends can flip entirely. Validation studies like this one are the quality-control step that keeps the pipeline honest.

The Brigham and Women’s team has now built something of a validation program across inflammatory skin diseases. In 2021, Barbieri and colleagues published a similar analysis for acne, determining which ICD-10 code strategies most accurately identified dermatology patients with that condition. In 2025, Ershadi, Biba, Bensellam, and colleagues, many of them on the current paper, extended the approach to perioral dermatitis, a facial eruption that shares features with rosacea and is easily confused with it. The new rosacea study completes a natural trilogy, giving researchers validated code definitions for three of the most common papulopustular and erythematous facial dermatoses seen in clinic.

Why does rosacea present a particular classification challenge? Part of the answer lies in the structure of the ICD-10 system itself. Rosacea occupies a cluster of codes within the dermatitis section of the classification, with separate codes for different subtypes and presentations, and clinicians vary widely in how precisely they code. Some records carry a specific rosacea code, others a broader facial dermatitis code, and still others a code for an unrelated condition that the clinician used to describe a rosacea-like presentation. In addition, conditions such as seborrheic dermatitis, lupus erythematosus, steroid-induced facial erythema, and perioral dermatitis can mimic rosacea clinically, meaning that a code-based cohort will inevitably pull in some patients who do not have the disease at all unless the coding strategy is chosen carefully.

The methodological logic of a chart review validation is straightforward even if the work is painstaking. The investigators define a set of candidate code strategies, for example a single specific code versus a broader set of codes, or codes restricted to dermatology encounters versus codes from any clinical setting. They then identify patients whose records match each strategy and manually review the clinical documentation, including physician notes and diagnoses, to determine whether the patient truly has rosacea. Each strategy can then be scored on measures such as positive predictive value, the proportion of code-identified patients who genuinely have the disease. A strategy that casts a wide net may capture nearly everyone but drown the cohort in false positives, while a narrow strategy may be highly accurate but miss many patients. The optimal choice depends on the research question, and the value of this study is that it tells researchers exactly where those trade-offs fall.

The research was reviewed and approved by the Mass General Brigham Institutional Review Board, and the authors report their funding as none, with disclosed consulting relationships for several senior authors unrelated to the present work. The study appears as a research letter, a compact format that journals use for focused validation analyses whose conclusions are precise but narrow. That format suits the findings well: the deliverable is not a sweeping new theory of disease but a set of practical, evidence-based recommendations that other investigators can adopt immediately when constructing rosacea cohorts from claims databases or electronic health record systems.

The implications ripple outward across dermatology research. Observational studies of rosacea treatments, investigations of reported associations between rosacea and cardiovascular, gastrointestinal, or neurological disease, and pharmacoepidemiology of systemic therapies all depend on cohort definitions built from billing codes. A misclassified cohort could exaggerate or erase a genuine association, and inconsistent definitions across studies make meta-analysis nearly impossible. By establishing a validated standard, the Boston team gives the field a common yardstick, much as their earlier acne and perioral dermatitis validations did for those conditions. Journals and reviewers can now reasonably ask authors of rosacea database studies which validated code strategy they used and why.

There is also a broader lesson here about the infrastructure of modern medical science. As health systems digitize their records and machine learning models are trained on clinical data, the humble diagnostic code has become one of the most consequential pieces of metadata in medicine. Studies like this one, unglamorous as they may seem, are the calibration experiments that determine whether the resulting science is trustworthy. For the millions of people worldwide who live with the flushing, burning, and stigma of rosacea, better-validated data means faster progress toward understanding who develops the disease, why it flares, and which treatments genuinely work. The Brigham and Women’s group has shown, once again, that in the era of big data, the most important findings sometimes begin with a careful look at how we count.

Subject of Research: Validation of ICD-10 code-based classification strategies for identifying rosacea patients in retrospective medical record data

Article Title: Validating optimal ICD-10 classification approaches to identify patients with rosacea: a retrospective chart review

Article References: Acevedo-Fontanez, L. A., Bensellam, N., Ershadi, S., Biba, U., Sanchez, K., Cheng, D., Gregoire, S., Vazquez-Machado, M. C., Mostaghimi, A., & Barbieri, J. S. (2026). Validating optimal ICD-10 classification approaches to identify patients with rosacea: a retrospective chart review. Archives of Dermatological Research, 318(1), Article 452. https://doi.org/10.1007/s00403-026-04817-y

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04817-y

Keywords: rosacea, ICD-10, medical coding, electronic health records, dermatology, retrospective chart review, validation study, diagnostic classification, dermatoepidemiology, Brigham and Women's Hospital, big data, skin disease

Demodex folliculorum is not a fringe pathogen. Nearly every adult human carries colonies of these mites in facial follicles, where they feed on sebum and shed skin cells, and in most people they cause no harm at all. Problems arise when populations expand beyond normal levels, a condition known as demodicosis, which is increasingly recognized as a driver or aggravating factor in rosacea, blepharitis, perioral dermatitis, and other chronic inflammatory conditions. Overgrowth has been linked to immune dysregulation, bacterial proliferation within the mites, and disruption of the follicular environment. Topical ivermectin one percent remains the best-characterized treatment, but clinicians have reported refractory cases in which mites persist despite repeated courses, and the drug’s price places it out of reach for many patients in low- and middle-income countries. That therapeutic gap is precisely what motivated Anon Paichitrojjana of the School of Anti-Aging and Regenerative Medicine to systematically screen lemongrass preparations against the mite.

The experimental design was deliberately comparative. Mites were harvested from residual material on standardized skin surface biopsy slides, a routine diagnostic technique in which cyanoacrylate adhesive is used to extract follicular contents from the skin of patients being evaluated for demodicosis and rosacea. Because the study used only leftover diagnostic specimens, the Mae Fah Luang Ethics Committee on Human Research waived the requirement for written informed consent, judging the work minimal risk, and the protocol was approved under the principles of the Declaration of Helsinki. Ten mites were assigned to each of nine test agents: lemongrass essential oil alone, lemongrass ethanolic extract alone, a three-part mixture of essential oil, extract, and ninety-five percent ethanol in a one-to-one-to-one ratio, a second three-part mixture replacing the ethanol with PEG-40 hydrogenated castor oil in a one-to-one-to-zero-point-five ratio, ivermectin one percent, ethanol alone, PEG-40 alone, essential oil diluted in immersion oil, and immersion oil as the negative control. Survival was tracked microscopically, with mites considered dead when they showed no movement.

The results were unambiguous. All mites exposed to any of the active test agents died within forty-four minutes, whereas mites suspended in immersion oil, the inert control, remained alive for more than two hundred forty minutes of observation. The two combined lemongrass formulations, the essential-oil-plus-extract mixtures containing either ethanol or PEG-40, produced the shortest survival times of any agent tested under the study conditions. Notably, ninety-five percent ethanol on its own also demonstrated substantial acaricidal activity, a detail that matters enormously for interpreting the data, because it means the ethanol vehicle in the combination formulations cannot be assumed to be biologically inert. Ivermectin one percent, included as a reference agent, killed mites within the same overall window, confirming that the assay could detect clinically meaningful acaricidal activity.

What makes lemongrass lethal to a mite? The chemistry of Cymbopogon citratus offers plausible mechanisms. Lemongrass essential oil is dominated by citral, a mixture of the isomeric aldehydes geranial and neral, which are known to disrupt insect and arachnid cell membranes and interfere with mitochondrial respiration. Essential oils in general act as neurotoxicants and membrane disruptors in arthropods, and their lipophilic constituents penetrate the cuticle readily. The ethanolic extract, by contrast, contains a broader and less volatile profile of compounds, including phenolic acids and flavonoids, which may contribute oxidative stress or additional membrane damage. The logic of combining the essential oil with the extract is that the two preparations deliver complementary phytochemical payloads, while the ethanol or PEG-40 component serves as a solubilizer that keeps the hydrophobic oil dispersed and may itself enhance penetration of active compounds into the mite’s protective cuticle.

The inclusion of PEG-40 hydrogenated castor oil is particularly interesting from a formulation science perspective. Ethanol is an effective solvent but a well-known skin irritant and drying agent, especially problematic for patients whose skin barrier is already compromised by rosacea or demodicosis. PEG-40 hydrogenated castor oil is a nonionic surfactant and solubilizer widely used in cosmetics precisely because it can disperse essential oils in aqueous formulations while being far gentler on the skin. The fact that the PEG-40-containing lemongrass formulation matched the ethanol-containing version for speed of kill suggests that a less irritating vehicle could achieve equivalent acaricidal performance, which would be a meaningful advantage if these laboratory findings ever translate into a topical product for inflamed, sensitive facial skin.

The author and the journal are appropriately cautious about what the study does and does not show. This was an in vitro assay on mites removed from their follicular habitat, observed in small numbers, ten per agent, under artificial conditions. The skin surface biopsy environment is not the same as a living follicle, where mites burrow head-down in sebum, protected by host tissue, and where a topical agent must penetrate the follicular opening and the mite’s cuticle simultaneously. The study itself acknowledges that further work is needed to clarify the individual contributions of each component, since the combination design means the observed effect cannot yet be attributed to citral, the extract’s phenolics, the ethanol, or the surfactant acting alone or in synergy. Safety, formulation stability, and clinical efficacy all remain untested, and the author explicitly frames the findings as support for further investigation rather than a treatment recommendation.

Those caveats notwithstanding, the study arrives at a moment of genuine unmet need. Demodex-associated dermatoses are chronic, relapsing, and psychologically burdensome, and treatment options beyond ivermectin are limited. Tea tree oil, the other botanical agent with documented demodicidal activity, has been formulated into commercial cleansers and eyelid wipes, but it too can cause irritation and allergic contact dermatitis in a subset of patients. A lemongrass-based alternative with rapid killing kinetics would add a second botanical option and potentially allow combination or rotation strategies for resistant cases. The open-access publication, funded by publication charges from Mae Fah Luang University with no external funding for the research itself and no competing interests declared, makes the full methods available to any laboratory wishing to replicate or extend the work.

The next steps are well defined by the field’s standard progression. Follow-up studies would need to isolate and quantify the active constituents, likely using gas chromatography-mass spectrometry to characterize the essential oil and high-performance liquid chromatography to profile the extract, then test purified citral and other candidates individually to establish dose-response relationships and minimum lethal concentrations. Formulation stability testing, preservative challenges, and ocular safety assessment would be essential for any product intended for the eyelid margin, where Demodex blepharitis is common. Ultimately, randomized clinical trials comparing a lemongrass formulation against vehicle and against ivermectin in patients with confirmed demodicosis would determine whether the forty-four-minute laboratory kill translates into real-world clearance of mites and resolution of inflammatory disease. Until then, the study stands as an intriguing proof of concept: a humble culinary herb, rigorously tested, outpacing a pharmaceutical standard in the petri dish.

Subject of Research: In vitro acaricidal activity of lemongrass preparations against the human follicle mite Demodex folliculorum

Article Title: Comparative in vitro acaricidal activity of lemongrass preparations and selected formulations against Demodex folliculorum

Article References: Paichitrojjana, A. (2026). Comparative in vitro acaricidal activity of lemongrass preparations and selected formulations against Demodex folliculorum. BMC Complementary Medicine and Therapies. https://doi.org/10.1186/s12906-026-05591-0

Image Credits: AI Generated

DOI: 10.1186/s12906-026-05591-0

Keywords: Demodex folliculorum, lemongrass essential oil, Cymbopogon citratus, demodicosis, rosacea, acaricidal activity, ivermectin, essential oil, topical formulation, in vitro assay, natural products, dermatology

The study, published on 28 September 2026 as a research letter in volume 318 of the journal, takes a retrospective approach. Rather than recruiting patients prospectively and following them over time, the authors mined existing electronic health records to identify individuals who received a rosacea diagnosis and to characterize the population in which new diagnoses appear. This design is increasingly popular in epidemiology because it leverages the enormous volume of clinical documentation generated by routine care, allowing researchers to examine disease patterns across millions of patients without the cost and duration of a traditional cohort study.

The data source underlying the analysis is TriNetX, a federated health research network that aggregates de-identified electronic medical records from contributing healthcare organizations, primarily large academic medical centers and integrated health systems across the United States. The platform allows investigators to run queries against this pooled data while the records themselves remain with the originating institutions, a structure that has made it a workhorse for observational studies in recent years. The authors note that the data supporting their findings are publicly available on TriNetX, which aligns with a broader push toward transparency and reproducibility in real-world evidence research.

Why does an incidence estimate for rosacea matter so much? Prevalence figures, which describe how many people live with the condition at a given time, have varied widely in the literature, in part because rosacea is a clinical diagnosis without a definitive laboratory test, and in part because many people with mild symptoms never seek medical care. A widely cited review by Rainer, Kang, and Chien published in Dermato-Endocrinology in 2017 highlighted that estimates of rosacea prevalence have ranged dramatically across populations and study designs, complicating efforts to understand the disease’s true burden. Incidence, the rate of new cases, is even harder to pin down, because it requires distinguishing genuinely new diagnoses from the documentation of longstanding disease in patients who are new to a health system.

The stakes of getting these numbers right extend well beyond academic curiosity. Rosacea is not merely a cosmetic nuisance. Research led by Moustafa, Lewallen, and Feldman, published in the Journal of the American Academy of Dermatology in 2014, examined the psychological impact of rosacea and concluded that the condition carries a substantial emotional burden, with effects on self-esteem, social interactions, and quality of life comparable in some respects to other highly visible chronic skin diseases. Patients describe anxiety about facial flushing in public settings, avoidance of triggers such as spicy food, alcohol, heat, and emotional stress, and frustration with treatments that control but rarely eliminate symptoms. A more recent comprehensive review of rosacea management published in the Journal of Cosmetic Dermatology in 2022 underscored that while therapeutic options have expanded, the condition remains chronic and relapsing for most patients.

Understanding how many people develop rosacea each year informs resource allocation in dermatology, guides pharmaceutical investment in new therapies, and provides a baseline against which future changes, whether environmental, demographic, or diagnostic, can be measured. It also matters for research into the disease’s pathogenesis. Rosacea has been linked to abnormalities in the innate immune system, neurovascular dysregulation, Demodex mites on the skin, and an assortment of genetic and environmental risk factors, but the relative contributions of these mechanisms remain debated. Solid epidemiological data help researchers identify which populations are most affected and where to focus mechanistic studies.

The TriNetX approach also connects this work to a lively methodological conversation. A 2025 critical review by Nassar and colleagues examined the strengths, limitations, and bias considerations of TriNetX in clinical research, noting that while the platform offers unprecedented scale, it inherits the biases of the underlying records. Patients in the network are those who present to participating healthcare organizations, which may skew toward sicker, more insured, or more urban populations. Coding practices vary across institutions, and a diagnosis code for rosacea may reflect anything from a confident specialist diagnosis to a working impression by a primary care clinician. The Stony Brook authors’ decision to publish in a dermatology research journal with the data availability statement pointing back to TriNetX reflects a growing norm of making the provenance of real-world evidence explicit so that readers can weigh these caveats themselves.

Retrospective designs like this one sit within a longer tradition of rosacea epidemiology. One of the most influential prior efforts, a study by Spoendlin and colleagues published in the British Journal of Dermatology in 2012, examined the epidemiology of rosacea in the United Kingdom using routine health records, providing one of the best-characterized national pictures of the disease. Comparing United States figures against such international benchmarks helps clarify whether rosacea truly varies across populations and climates, as some hypotheses about sun exposure and skin phototype would predict, or whether earlier variation simply reflected differences in how the disease was counted. The condition is classically associated with fair-skinned individuals of Northern European descent, but it is increasingly recognized across all skin tones, where it may be underdiagnosed because erythema is harder to visualize on darker skin.

For clinicians, the practical takeaway from this kind of study is a clearer sense of the expected flow of new rosacea diagnoses through the healthcare system, which can inform screening awareness, referral patterns, and patient education. For patients, better epidemiology supports advocacy and awareness efforts, including the kind of public health messaging that has successfully raised the profile of conditions like psoriasis and acne. Rosacea has historically received less attention relative to its prevalence and its documented impact on quality of life, and hard numbers are the currency in which that attention is won.

The research letter format itself is worth noting. Archives of Dermatological Research, published by Springer Nature, offers research letters as a concise vehicle for focused findings, and the brevity of the format means that readers should look to the full article for the precise incidence estimates, stratifications by age and sex, and sensitivity analyses that determine how robust the numbers are. What the publication establishes is a contemporary, data-driven baseline for rosacea incidence in the United States, built on one of the largest aggregated clinical data networks available, from a team at Stony Brook University with no declared competing interests. As real-world evidence continues to reshape dermatological epidemiology, studies of this kind are likely to become the standard reference points against which the field measures both the burden of rosacea and the success of future efforts to treat and perhaps prevent it.

Subject of Research: Epidemiology of rosacea incidence in the United States using real-world electronic health record data

Article Title: Incidence of Rosacea in the United States: a retrospective study using real-world data

Article References: Basharat, R., & Iqbal, J. (2026). Incidence of Rosacea in the United States: a retrospective study using real-world data. Archives of Dermatological Research, 318(1), Article 485. https://doi.org/10.1007/s00403-026-04977-x

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04977-x

Keywords: rosacea, incidence, epidemiology, TriNetX, real-world data, dermatology, retrospective study, electronic health records, skin disease, Stony Brook University, Archives of Dermatological Research, facial redness