A widely used medication for erectile dysfunction and enlarged prostate symptoms may also increase the risk of developing glaucoma, a serious eye disease that can cause permanent vision loss, according to new research.
Tadalafil, known by the brand name Cialis, belongs to a class of drugs called phosphodiesterase type 5 inhibitors (PDE5 inhibitors). These medications work by relaxing and widening blood vessels to improve blood flow. While effective for treating erectile dysfunction, tadalafil is also approved for alleviating symptoms associated with an enlarged prostate, such as a weak urine stream and frequent urination.
Researchers at National Taiwan University Hospital in Taipei analyzed health data from nearly 74,000 men aged 40 and older to investigate a potential link between tadalafil use and glaucoma. The study compared men who had been taking tadalafil or another PDE5 inhibitor for up to five years to treat urinary symptoms with a control group that had not used these medications.
The findings indicated that men prescribed tadalafil were 22% more likely to develop glaucoma compared to those not taking PDE5 inhibitors. This risk increased to 33% for primary open-angle glaucoma, the most common form of the disease. Additionally, participants using tadalafil showed a 32% higher risk of developing ocular hypertension, characterized by abnormally high pressure inside the eye, a significant risk factor for glaucoma. The study noted that this increased risk was observed even after short periods of use, with some cases showing a link after just one month.
"Tadalafil use for [lower urinary tract symptoms] was associated with a statistically significant but modest increase in glaucoma risk," the study authors concluded. However, they emphasized that the study was observational, meaning it could identify a correlation but not definitively prove causation.
Despite the findings, the researchers advised against discontinuing the medication without consulting a doctor. They suggested that regular eye checkups might be beneficial for men taking tadalafil, particularly those with a predisposition to glaucoma. In the United States, an estimated 5 million tadalafil prescriptions were issued to over 1 million men in 2024 alone, highlighting the large number of individuals who could potentially be affected.
Glaucoma affects an estimated 4.22 million American adults, with nearly half unaware they have the condition due to its often asymptomatic progression. It is a leading cause of blindness in individuals over 60. While there is no cure for glaucoma, early detection and treatment, which can include prescription eye drops, oral medications, or surgery, can help manage the disease and slow its advancement.
Common risk factors for glaucoma include high intraocular pressure, a family history of the disease, severe nearsightedness or farsightedness, previous eye injuries, and long-term use of corticosteroid medications. Age, with increased prevalence over 55, and ethnicity, with higher risk among Black, Asian, or Hispanic individuals, are also factors. Certain health conditions, such as diabetes, migraines, high blood pressure, and sickle cell anemia, can further elevate the risk.