Long use of a common prostate pill is tied to a higher chance of glaucoma

A large international study has found that men who take the erectile dysfunction drug tadalafil for years to manage urinary symptoms from an enlarged prostate are more likely to develop glaucoma than men who are never prescribed the medication. The study cannot prove that tadalafil causes the eye condition, since it only tracked outcomes already on medical record rather than testing the drug directly against a placebo, but the size of the dataset and the consistency of the pattern have prompted researchers to recommend closer eye monitoring for men on long-term treatment.

A Prostate Drug Dosed Very Differently From an ED Pill

Tadalafil, sold under the brand name Cialis, belongs to a class of medicines called phosphodiesterase type 5 inhibitors, the same family as sildenafil. Taken on demand for erectile dysfunction, tadalafil is used occasionally and briefly. Prescribed for lower urinary tract symptoms linked to benign prostatic hyperplasia, an enlarged prostate common in older men, it is typically taken daily at a lower dose, often for years, to ease urgency, frequency and nighttime urination. Researchers behind the new study noted that earlier evidence connecting PDE5 inhibitors to glaucoma was patchy and inconclusive, and that almost none of it examined this long-term, low-dose daily pattern specifically, as opposed to occasional ED use.

Matching 73,854 Men Inside a Global Health Network

The research team drew anonymised records for 73,854 men aged 40 and older from the TriNetX Analytics Network, a health-records database drawing on clinics across multiple countries. Roughly half had been prescribed tadalafil or another PDE5 inhibitor for lower urinary tract symptoms between January 2012 and December 2022, in some cases for up to five years; the other half, matched for comparison, had not received these drugs. Pairs were matched on age, ethnicity, smoking status, alcohol-related disorders and a wide list of underlying conditions, including cardiovascular disease, diabetes, cancer, high cholesterol, kidney function, obesity and chronic obstructive pulmonary disease, along with other prescribed medications. Researchers then compared how often each group went on to develop glaucoma, develop ocular hypertension or start glaucoma treatment.

A 22 Per Cent Higher Rate of Glaucoma

Men prescribed tadalafil were 22 per cent more likely to develop glaucoma over five years than men who were not on a PDE5 inhibitor. They were also 32 per cent more likely to develop ocular hypertension, a buildup of pressure inside the eye that is itself a glaucoma risk factor, 33 per cent more likely to be diagnosed with primary open angle glaucoma specifically, the most common form of the disease, and 33 per cent more likely to start glaucoma treatment altogether. The pattern held up when researchers looked separately at men who developed glaucoma within one, three or six months of starting tadalafil, and it appeared consistently among men over 50, men of White ethnicity and men carrying a range of the underlying conditions built into the matching process.

What an Observational Study Cannot Settle

Because the study only observed prescriptions and outcomes already on record, it cannot establish that tadalafil causes glaucoma rather than simply appearing alongside it. The researchers could not account for changes in medication use or the emergence of other health conditions over the five-year follow-up window, and most of the men in the analysis were White, so the results may not translate directly to men of other backgrounds. Even with those caveats, the authors wrote that the findings “suggest that chronic PDE5 inhibition may influence ocular physiology, warranting further mechanistic investigation.” PDE5 inhibitors work in part by relaxing blood vessels, and researchers suspect that mechanism, useful for treating urinary symptoms, could also alter blood flow around the optic nerve over years of continuous use. Earlier research has separately linked the drug class to other eye conditions involving the optic nerve and the macula, the part of the retina responsible for sharp central vision, including a rare form of sudden vision loss called non-arteritic anterior ischemic optic neuropathy that regulators have already flagged on some PDE5 inhibitor labeling. The new study does not attempt to explain glaucoma through that same pathway, but it adds to a wider pattern of eye-related signals tied to long-term use of the drug class.

Monitoring Eyes, Not Abandoning the Drug

The researchers were explicit that their results are not a reason to stop prescribing tadalafil for urinary symptoms, which remains an externally peer-reviewed treatment option alongside alpha-blockers and other medications used for the same symptoms. In their own words, published alongside the study in the British Journal of Ophthalmology, the findings “do not contraindicate tadalafil use but highlight the importance of baseline ophthalmic assessment and regular follow-up,” particularly for patients who already carry glaucoma risk factors such as a family history of the disease, existing ocular hypertension, high myopia, or an expectation of long-term therapy. For men currently prescribed tadalafil for BPH-related symptoms, the practical takeaway researchers point to is a conversation with a doctor about a baseline eye exam and periodic rechecks, not a reason to discontinue treatment on their own. Glaucoma itself often develops without early symptoms, which is part of why the researchers frame regular screening, rather than a change in prescribing, as the more immediate response to their findings.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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