Men who take the erectile-dysfunction drug tadalafil long-term for urinary symptoms caused by an enlarged prostate face a modestly higher risk of developing glaucoma, according to a large multinational study published in the British Journal of Ophthalmology. The researchers stopped short of saying the drug, sold under the brand name Cialis among others, causes the eye disease, but recommended that long-term users get their eye pressure checked.
The study, led by Yun Hsia of National Taiwan University Hospital, analyzed anonymized health records from the TriNetX Analytics Network covering 73,854 men age 40 and older with lower urinary tract symptoms between 2012 and 2022. Roughly 37,000 men prescribed tadalafil were matched against a similar number of men who were not taking any phosphodiesterase type 5 inhibitor, the drug class that includes tadalafil and sildenafil, controlling for age, ethnicity, smoking, alcohol use disorder and other medications and health conditions.
What the numbers show
Over as long as five years of follow-up, men taking tadalafil were 22% more likely to be diagnosed with glaucoma, 32% more likely to develop ocular hypertension — elevated pressure inside the eye that is a major glaucoma risk factor — and 33% more likely to be diagnosed specifically with primary open-angle glaucoma, the most common form of the disease, or to start glaucoma treatment, according to the BMJ Group summary of the findings.
The authors were careful to frame the results as an association rather than proof of cause and effect, a standard limitation of observational cohort studies that compare existing patient records rather than randomly assigning treatment. "These findings suggest that chronic PDE5 inhibition may influence ocular physiology, warranting further mechanistic investigation," the researchers wrote, according to coverage in ScienceDaily. They also noted the study population was predominantly white, which may limit how well the findings apply to other ethnic groups, and that the database could not confirm patients actually took the medication as prescribed.
Tadalafil is widely prescribed both for erectile dysfunction and, at lower daily doses, for benign prostatic hyperplasia, the non-cancerous prostate enlargement that causes frequent or difficult urination in many older men. The study's authors said the results "do not contraindicate tadalafil use" but "highlight the importance of baseline ophthalmic assessment and regular follow-up," particularly for patients who already have glaucoma, ocular hypertension, a family history of glaucoma, high myopia, or who expect to take the drug for years.
Glaucoma, a group of eye conditions that damage the optic nerve, often progresses with no symptoms until significant vision loss has already occurred, which is why the researchers are urging eye screening rather than a change in prescribing practice. Physicians who prescribe tadalafil for urinary symptoms, the authors said, should weigh building an eye exam into routine care for patients expected to stay on the drug long-term.
