A popular bedroom helper could be more than meets the eye.
New research suggests that a widely used erectile dysfunction drug may also raise the risk of developing a serious eye disease that can cause permanent vision loss.
And you don’t even have to be taking it for a lift below the belt. The study focused on patients prescribed the medication to treat a common age-related condition that affects more than half of men by age 60.
The drug, tadalafil, is better known by its brand name, Cialis. It belongs to a class of medications called phosphodiesterase type 5 inhibitors, or PDE5 inhibitors.
These treatments work by relaxing and widening blood vessels, helping increase blood flow to the penis and making it easier to get an erection.
But tadalafil is also approved to treat symptoms of an enlarged prostate, which can include a weak urine stream, a frequent or urgent need to pee and the frustrating feeling that your bladder still isn’t empty after you’ve gone to the bathroom.
While the drugs are considered effective for both uses, previous research has raised concerns about their potential effects on the eyes.
Curious if it could raise the risk of glaucoma — a group of diseases that damage the optic nerve and can eventually rob you of your sight — researchers at the National Taiwan University Hospital in Taipei took a closer look.
For the study, the team analyzed health data from nearly 74,000 men ages 40 and older. About half had been taking tadalafil or another PDE5 inhibitor for up to five years to treat urinary symptoms, while the rest hadn’t taken the drugs.
They found that men prescribed tadalafil were 22% more likely to develop glaucoma than those who hadn’t taken a PDE5 inhibitor. That figure rose to 33% for primary open-angle glaucoma, the most common form of the disease.
Participants taking the drug also had a 32% higher risk of developing ocular hypertension, or abnormally high pressure inside the eye and a major risk factor for glaucoma.
And the potential link showed up regardless of how long the men had been taking the pills, with the increased risk appearing in some cases after just one month of use.
“Tadalafil use for [lower urinary tract symptoms] was associated with a statistically significant but modest increase in glaucoma risk,” the study authors concluded.
But that doesn’t mean men taking the medication should stop. The researchers stressed that their study was observational, meaning it can identify a potential link but can’t prove that tadalafil itself caused the increased risk.
Still, they said regular eye checkups may be worth considering for men taking the drug, particularly those who may already be predisposed to glaucoma.
And with research suggesting that an estimated 5 million tadalafil prescriptions were written for more than 1 million men in the US in 2024 alone, that’s a lot of people who could be affected.
Across the country, glaucoma affects an estimated 4.22 million American adults, but nearly half don’t know they have it. That’s because the disease often has no warning signs, quietly damaging the eyes until it reaches more advanced stages.
While glaucoma can develop at any age, it becomes more common with age and is one of the leading causes of blindness among people over 60, according to the Mayo Clinic.
There’s currently no cure for glaucoma, and the vision loss it causes can’t be reversed. But catching the disease early and treating it with prescription eye drops, oral medications or, in some cases, surgery can help manage it and slow its progression.
That, experts say, makes it important to know the risk factors — including medications that could potentially increase your chances of developing the disease.
Common risk factors include high pressure inside the eye, a family history of glaucoma, extreme nearsightedness or farsightedness, previous eye injuries and long-term use of corticosteroid medications, particularly steroid eye drops.
People over 55, as well as those of Black, Asian or Hispanic descent, face a higher risk. Certain health conditions, including diabetes, migraine, high blood pressure and sickle cell anemia, can also increase the odds of developing glaucoma.
