FAERS is the FDA’s primary spontaneous reporting database, a vast repository where physicians, pharmacists, patients, and manufacturers file accounts of suspected adverse drug events. Because anyone can submit a report and the FDA does not verify causation, the database is inherently noisy. A drug that is prescribed to millions will naturally accumulate more reports of every kind than a rarely used medication. To correct for this, pharmacovigilance researchers rely on disproportionality analysis, a family of statistical techniques that compares how often a specific adverse event is reported with a given drug against how often it is reported across the database as a whole. When a drug-event pair shows up far more frequently than chance would predict, it earns a statistical flag known as a reporting odds ratio, signaling that the association deserves closer clinical attention even though it cannot by itself prove cause and effect.

The Rutgers-led team, including first authors Priya Agarwal and Aryan Mahajan along with senior investigators Gaurav N. Pathak and Babar K. Rao, applied this framework to FAERS records spanning 2018 through 2024, focusing on reports of alopecia among patients exposed to biologic therapies. Their analysis revealed high reporting odds of hair loss across the biologic class, a finding consistent with a growing body of case reports and systematic reviews documenting drug-induced alopecia in patients treated with agents ranging from tumor necrosis factor inhibitors to B-cell-depleting antibodies. The study joins a broader wave of FAERS-based safety analyses that have, in recent years, surfaced unexpected signals for everything from Sweet’s syndrome to dermatologic complications of atopic dermatitis biologics, demonstrating how spontaneous reporting can illuminate risks that never surfaced in premarketing trials.

The biological plausibility behind these signals is an active area of investigation. Hair follicles exist in a delicate cycle of growth, regression, and rest, and that cycle is tightly regulated by immune signaling. Cytokines such as tumor necrosis factor alpha and interferons help orchestrate the immune privilege that protects the follicle from inflammatory attack, and disrupting that privilege can push follicles into premature rest or trigger inflammatory scarring. Biologics, by design, perturb these very pathways. Tumor necrosis factor inhibitors, interleukin blockers, and agents that deplete B cells each alter the cytokine milieu surrounding the follicle in distinct ways, and case reports have described patterns ranging from diffuse telogen effluvium to severe alopecia universalis following rituximab treatment, and dramatic hair loss with scalp psoriasis flares after infliximab exposure in patients with Crohn’s disease.

What makes the new analysis particularly timely is the sheer scale of biologic prescribing. Drugs in this class, including adalimumab, etanercept, infliximab, rituximab, dupilumab, tralokinumab, and the interleukin-17 and interleukin-23 inhibitors used in psoriasis, now rank among the best-selling medicines in the world, and biosimilar competition is driving costs down and access up. A recent commentary in The Lancet examined how nationalized health systems have leveraged biosimilars to expand biologic therapy to larger patient populations. As exposure grows, even a modest absolute risk of an adverse event translates into a meaningful number of affected patients, which is precisely the scenario in which pharmacovigilance databases earn their keep. A signal that would be invisible in a clinical trial of a few thousand participants can emerge clearly from millions of real-world exposure years.

Interpreting the alopecia signal, however, requires careful attention to the quirks of spontaneous reporting. Patients taking biologics often have underlying conditions, such as psoriasis or inflammatory bowel disease, that are themselves associated with hair changes, and many receive concomitant medications, including methotrexate, that are well-known causes of hair loss. Reporting behavior is also shaped by publicity: once a possible side effect gains attention in the literature or the press, reports of it tend to rise, a phenomenon known as notoriety bias. Furthermore, FAERS lacks a reliable denominator of exposed patients, so reporting odds reflect the relative frequency of reports rather than the true incidence of events in the treated population. The authors of the research letter are careful to frame their findings as hypothesis-generating, a call for targeted studies rather than a verdict on causation.

That framing matters because the clinical stakes are real. Alopecia is not life-threatening, but its psychological burden can be profound, particularly for patients already coping with chronic visible disease. A systematic review published in the Journal of the American Academy of Dermatology catalogued the growing evidence for drug-induced alopecia areata, noting that immune-modulating therapies can occasionally trigger the very hair-loss condition they might be expected to prevent in some contexts. Case reports describe patients whose hair loss resolved after drug discontinuation, while others required systemic and topical therapies to manage persistent alopecia. For dermatologists and other prescribers, the practical takeaway is vigilance: asking about hair changes at follow-up visits, documenting onset relative to biologic initiation, and considering whether a pattern of hair loss warrants a change in therapy.

The study also speaks to a methodological shift in how drug safety is monitored. Traditional clinical trials enroll selected patients for limited durations, capturing common and expected adverse events but often missing rare, delayed, or subtle ones. Spontaneous reporting systems like FAERS, alongside claims databases and national registries, fill that gap by surveilling the full breadth of real-world use. Recent FAERS analyses have assessed the real-world safety of tralokinumab for atopic dermatitis and characterized drug-induced Sweet’s syndrome using sophisticated statistical tools, including multivariable logistic regression and cross-database comparisons with the World Health Organization’s VigiBase. The Rutgers team’s alopecia analysis extends this approach to one of the most widely prescribed drug classes in medicine, illustrating how a research letter drawing on public data can generate clinically actionable hypotheses without a single new patient encounter.

For patients, the message is not alarm but awareness. Biologics remain among the most effective and well-studied therapies available for severe inflammatory disease, and for most patients the benefits decisively outweigh the risks. Hair loss remains an uncommon and incompletely understood association, and the FAERS signal does not establish that any particular biologic causes alopecia at any particular rate. What it does establish is that the question is worth asking. Patients who notice unusual shedding, patchy hair loss, or thinning after starting a biologic should report it to their prescribing physician rather than assume it is unrelated, both because early recognition can guide management and because patient reports feed the very surveillance systems that surface these signals in the first place.

The road from statistical signal to clinical certainty is long. Confirming a causal link between biologics and alopecia will require controlled epidemiological studies with proper exposure denominators, mechanistic work clarifying how cytokine blockade affects follicular immune privilege, and possibly prospective registries tracking hair outcomes in biologic-treated cohorts. Until then, the Rutgers and Weill Cornell analysis stands as a reminder that the pharmacovigilance apparatus humming quietly in the background of modern medicine is doing its job, scanning millions of adverse event reports for patterns too rare or too subtle to appear anywhere else. As biologic therapies continue their march into primary care and newer agents reach the market, that quiet surveillance may prove to be one of the most important safety nets patients have, catching whispers of risk that no trial could hear.

Subject of Research: Pharmacovigilance analysis of alopecia reporting associated with biologic drugs in the FDA Adverse Event Reporting System

Article Title: High reporting odds of alopecia among biologics: insights from the FDA adverse events reporting system (FAERS) database from 2018 to 2024

Article References: Agarwal, P., Mahajan, A., Pathak, G. N., & Rao, B. K. (2026). High reporting odds of alopecia among biologics: insights from the FDA adverse events reporting system (FAERS) database from 2018 to 2024. Archives of Dermatological Research, 318(1), Article 508. https://doi.org/10.1007/s00403-026-04932-w

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04932-w

Keywords: biologics, alopecia, FAERS, pharmacovigilance, adverse drug events, drug safety, dermatology, reporting odds ratio, psoriasis, TNF inhibitors, hair loss, FDA