Men who took tadalafil over long stretches to manage urinary symptoms from an enlarged prostate were diagnosed with glaucoma more often than closely matched men who were not prescribed a drug in the same class, according to a comparison of 73,854 men published in the British Journal of Ophthalmology. Over five years, the tadalafil group was 22 percent more likely to receive a glaucoma diagnosis.
The size of that gap in plain terms is smaller than the percentage suggests. Just under 4 percent of tadalafil users were diagnosed with glaucoma within five years, compared with roughly 3 percent of the comparison group.
The drug is better known as Cialis. Most people associate it with erectile dysfunction, where it is taken as needed. The pattern in this analysis involves a different use: a low daily dose taken continuously, sometimes for years, to relieve benign prostatic hyperplasia. That is the population the researchers studied, and the distinction matters for anyone trying to work out whether the finding applies to them.
For the more than 3 million Americans who already have glaucoma, and the many more with risk factors they have never been screened for, the takeaway is narrow. The researchers are not telling anyone to stop taking the medication. They are saying some men taking it may warrant closer attention to their eyes.
The Numbers Behind the Five-Year Comparison
Researchers led by a team at National Taiwan University Hospital drew anonymized records from the TriNetX Analytics Network, covering men aged 40 and older with a history of lower urinary tract symptoms. The study compared 36,927 men prescribed tadalafil with 36,927 matched men who were not prescribed any drug in the PDE5 inhibitor class. Men already diagnosed with glaucoma were excluded, and the records ran from January 2012 through December 2022.
The two groups were matched on age, ethnicity, smoking, alcohol-related disorders, prescribed medications, kidney function, and underlying conditions including cardiovascular disease, diabetes, cancer, high cholesterol, obesity, and chronic obstructive pulmonary disease. That matching is what separates this from a simple before-and-after count.
Beyond the 22 percent figure for glaucoma overall, ocular hypertension was 32 percent more common in the tadalafil group. Primary open-angle glaucoma, the most common form of the disease, was 33 percent more likely, as was starting glaucoma treatment. The associations held among men older than 50, among White participants, and across several of the underlying conditions the researchers accounted for. No significant association appeared for normal-tension glaucoma or angle-closure glaucoma.
Tadalafil belongs to the same drug class as sildenafil, sold as Viagra. Earlier research had already connected this class to eye problems involving the optic nerve and the macula, though the evidence on glaucoma specifically had been patchy and inconclusive, according to the summary published by BMJ Group.
Eye Pressure Damage Arrives Without Warning Signs
Glaucoma is often called a silent thief of sight for a reason that makes this finding harder to shrug off. The most common forms produce no symptoms until damage to the optic nerve has already occurred, and vision that is lost does not come back.
The CDC's vision health program reports that more than 3 million Americans have glaucoma, a figure projected to reach 6.3 million by 2050 as the population ages, and that only about half of the people who have it know they do. The condition costs the U.S. economy about $2.86 billion a year in direct costs and lost productivity.
The overlap between that undiagnosed population and men on long-term prostate medication is why this study is worth a conversation with a doctor rather than a shrug.
Researchers Stop Short of Blaming the Drug
The study cannot establish that tadalafil causes glaucoma. It is observational, which means it can identify a pattern but not prove that one thing produced the other.
The limitations are meaningful, and the researchers named them. They could not account for changes in prescriptions or actual medication use over time. They could not fully track new health conditions developing during the study period. Most participants were White, so the findings may not extend to men from other backgrounds. Because the database was de-identified, individual records could not be reviewed to confirm diagnoses.
Their own framing is deliberately restrained. The authors wrote that chronic PDE5 inhibition may influence how the eye functions and that the mechanism warrants further investigation. On what patients should do, they were explicit: "These findings do not contraindicate tadalafil use." They pointed instead to the value of a baseline eye assessment and regular follow-up, particularly for patients with existing glaucoma, ocular hypertension, a family history of glaucoma, high myopia, or anyone needing long-term therapy.
That is a recommendation about monitoring, not about stopping.
Steps Worth Taking Before the Next Refill
Nobody should stop a prescribed medication based on a news story. Men taking tadalafil daily for prostate symptoms who also have a family history of glaucoma, elevated eye pressure, or significant nearsightedness have a reasonable basis to ask their prescriber whether a baseline eye exam is warranted, and how often it should be repeated.
Men taking the drug occasionally for erectile dysfunction are in a different situation from the long-term daily users this study examined, and the findings should not be read as applying equally.
Cost is a real barrier. Medicare Part B covers a glaucoma test once every 12 months for people considered at high risk, including those with diabetes, a family history of the disease, African Americans 50 and older, and Hispanic Americans 65 and older. Patients still pay 20 percent of the approved amount after the Part B deductible. Community health centers and some vision nonprofits offer reduced-cost screening for people without coverage.
Sudden eye pain, halos around lights, nausea with eye pain, or an abrupt change in vision requires urgent evaluation rather than a routine appointment.
MedicalDaily has separately reported on clinics marketing tadalafil as a longevity treatment to people without an approved indication. Those customers take the same continuous low dose examined here, without the prostate diagnosis that would normally bring them into regular medical follow-up. This study gives that trend a specific new question to answer.
Larger and more diverse studies would be needed to confirm the association, and mechanistic work would be needed to explain it. Current prescribing guidance has not changed.
Key Questions Answered
What did the study find? Among 73,854 matched men aged 40 and older, those prescribed tadalafil for urinary symptoms from an enlarged prostate were 22 percent more likely to be diagnosed with glaucoma over five years, 32 percent more likely to develop ocular hypertension, and 33 percent more likely to develop primary open-angle glaucoma.
How large is the risk in absolute terms? Just under 4 percent of tadalafil users were diagnosed with glaucoma within five years, compared with about 3 percent of the comparison group.
Does this mean Cialis causes glaucoma? No. The study is observational and identifies an association only. The researchers said explicitly that the findings do not contraindicate tadalafil use.
Should men stop taking tadalafil? No one should stop a prescribed medication without speaking to a clinician. The researchers recommended eye monitoring, not discontinuation.
Who should ask about an eye exam? Men on long-term daily tadalafil who also have existing glaucoma, ocular hypertension, a family history of glaucoma, high myopia, or who expect to stay on the drug indefinitely.
Does this apply to occasional Cialis or Viagra use? The study looked at continuous daily use for prostate symptoms. It does not directly address as-needed use for erectile dysfunction.
Is glaucoma screening covered by insurance? Medicare Part B covers a glaucoma test once every 12 months for people at high risk, with 20 percent coinsurance after the deductible. Community health centers may offer reduced-cost screening for the uninsured.
