A large multinational study has linked long-term use of tadalafil, the erectile dysfunction drug also prescribed for urinary symptoms caused by an enlarged prostate, with a modestly increased risk of glaucoma and related eye conditions. The findings, published online in the British Journal of Ophthalmology, suggest that men taking tadalafil daily for lower urinary tract symptoms may benefit from baseline eye examinations and regular ophthalmic follow-up, particularly if they already have risk factors for glaucoma.
Tadalafil, sold under the brand name Cialis, is widely recognized as a treatment for erectile dysfunction. It is also approved for symptoms associated with benign prostatic hyperplasia, or BPH, a noncancerous enlargement of the prostate that can obstruct urine flow. Men with BPH may experience frequent urination, sudden urgency, nighttime urination and difficulty emptying the bladder. Unlike occasional use for erectile dysfunction, treatment for these urinary symptoms often involves daily, long-term dosing.
The drug belongs to a class known as phosphodiesterase type 5 inhibitors, or PDE5 inhibitors. These medicines work by blocking the PDE5 enzyme, increasing levels of a signaling molecule called cyclic guanosine monophosphate. The resulting relaxation of smooth muscle improves blood flow and can help ease urinary obstruction. However, PDE5 inhibitors also affect blood vessels and signaling pathways in the eye, where related biochemical systems help regulate blood flow, retinal function and pressure inside the eyeball.
Previous research has associated PDE5 inhibitors with several visual complications, including rare disorders involving the optic nerve and the macula, the central region of the retina responsible for detailed vision. Their relationship with glaucoma, however, has remained uncertain. Glaucoma is not a single disease but a group of conditions that progressively damage the optic nerve, often without noticeable symptoms in its early stages. Elevated intraocular pressure, known as ocular hypertension, is an important risk factor, although glaucoma can also develop when eye pressure falls within the statistically normal range.
To investigate the possible connection, researchers analyzed anonymized medical records from the TriNetX Analytics Network, a multinational database containing health information from participating institutions. The study included 73,854 men aged 40 or older who had symptoms associated with BPH. Approximately half had been prescribed tadalafil or another PDE5 inhibitor for as long as five years between January 2012 and December 2022, while the remaining men had not received these medicines.
The investigators used statistical matching to make the treatment and comparison groups as similar as possible. The analysis accounted for age, ethnicity, smoking, alcohol-related disorders, obesity and a range of medical conditions, including cardiovascular disease, diabetes, cancer, high cholesterol, impaired kidney function and chronic obstructive pulmonary disease. The researchers also considered the use of other prescription medicines, an important step because multiple conditions and medications can influence both eye health and the likelihood of receiving tadalafil.
After five years, men prescribed tadalafil were 22 percent more likely to be diagnosed with glaucoma than comparable men who had not received the drug. The tadalafil group also had a 32 percent higher likelihood of developing ocular hypertension and a 33 percent higher likelihood of developing primary open-angle glaucoma, the most common form of the disease. They were likewise 33 percent more likely to begin treatment for glaucoma, suggesting that the statistical association was reflected not only in diagnostic records but also in clinical management.
Additional analyses indicated that the association remained visible among men diagnosed within one, three or six months of beginning tadalafil treatment. It was also consistently observed in men aged 50 and older, White participants and people with several of the underlying medical conditions included in the study. These results do not prove that tadalafil causes glaucoma, but the repeated pattern across different analyses has prompted the researchers to call for closer investigation of how prolonged PDE5 inhibition might influence ocular physiology.
One possible explanation involves the effects of PDE5 inhibitors on blood flow and pressure regulation in the optic nerve and retina. The optic nerve is supplied by a delicate network of small vessels, and changes in vascular signaling could theoretically affect its ability to withstand stress. The drugs may also influence fluid dynamics within the eye, although the biological mechanism remains unclear. The researchers emphasize that these possibilities require laboratory and clinical studies before any causal conclusion can be made.
The study has important limitations. Because it was observational, the researchers examined associations in existing medical records rather than assigning patients randomly to tadalafil or placebo. They could not fully account for changes in medication use over time, treatment adherence or the emergence of new health conditions during follow-up. Most participants were White, which may limit how broadly the findings apply to other ethnic groups. The results also do not establish that tadalafil is unsafe for all users or that patients should stop treatment without medical advice.
Instead, the researchers say the findings support a precautionary approach for men receiving tadalafil over extended periods. Patients with existing glaucoma, ocular hypertension, a family history of glaucoma, severe short-sightedness or other established risk factors may warrant particular attention from eye-care professionals. A baseline ophthalmic assessment, followed by appropriate monitoring, could help detect changes before substantial optic nerve damage occurs. For now, tadalafil remains an established treatment for erectile dysfunction and BPH, but the new evidence adds a potentially important consideration to conversations between patients, prescribing doctors and ophthalmologists.
Subject of Research: People
Article Title: Risk of glaucoma among patients using tadalafil for lower urinary tract symptoms: a multinational cohort study
News Publication Date: 4-Aug-2026
Web References: https://doi.org/10.1136/bjo-2026-329957
References: British Journal of Ophthalmology, DOI: 10.1136/bjo-2026-329957
Keywords: Glaucoma, medications, tadalafil, phosphodiesterase type 5 inhibitors, benign prostatic hyperplasia, ocular hypertension, primary open-angle glaucoma, eye health, erectile dysfunction
