Health & Wellness
Millions of Men Take This Drug — Few Know It Could Cost Them Their Sight
A new study links regular use of tadalafil, the active ingredient in Cialis, to a significantly higher risk of glaucoma — a disease that causes irreversible vision loss and often shows no early symptoms.
Health News · 6 min read
Illustration: eye health and long-term ED medication use.
For years, doctors have flagged erectile dysfunction drugs for a handful of well-known side effects — headaches, flushing, occasional dizziness. But a new study is adding something more serious to that list: a heightened risk of glaucoma, one of the leading causes of irreversible blindness worldwide.
The study
Published in the British Journal of Ophthalmology, the research looked at tadalafil — the active ingredient in Cialis, which is also commonly prescribed for enlarged prostate symptoms. An international team of researchers pulled health records from nearly 74,000 men aged 40 and older who had lower urinary tract symptoms, comparing about 37,000 men who were prescribed tadalafil against a similar group who weren't using any PDE5 inhibitors — the drug class that includes Cialis, Viagra, Levitra, and Stendra.
The men were followed for up to five years, with researchers tracking new diagnoses of glaucoma, elevated eye pressure, and whether patients eventually needed treatment.
The numbers
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22%
Higher risk of developing glaucoma among tadalafil users
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32%
Higher risk of elevated pressure inside the eye
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33%
Higher risk of primary open-angle glaucoma, the most common form
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Why this is easy to miss
One of the more concerning aspects of glaucoma is how quietly it progresses. Glaucoma often shows no symptoms in its early stages. By the time someone notices a problem, they're usually experiencing a gradual loss of peripheral vision — damage that, once it happens, can't be reversed.
Glaucoma typically produces no noticeable symptoms early on. As it progresses, patients tend to gradually lose peripheral vision rather than experience any sudden or obvious change. — Dr. Valerie Kattouf, optometrist, Illinois Eye Institute
That's what makes this finding worth paying attention to: it's not a side effect you'll necessarily feel until real damage has already occurred.
Not the first warning sign
This isn't the first time PDE5 inhibitors have come under scrutiny for eye-related effects. A 2022 study published in JAMA Ophthalmology linked regular use of these drugs to three other vision-damaging conditions — nonarteritic ischemic optic neuropathy, retinal vascular occlusion, and serous retinal detachment — even after adjusting for diabetes, high blood pressure, and heart disease. Researchers there noted that while the relative risk increase was notable, the absolute risk remained low.
Interestingly, earlier research from 2009 found no increased vision loss after six months of daily ED drug use, suggesting the risk may build gradually with long-term, sustained use rather than showing up quickly.
Should you be worried?
The researchers behind the new study aren't recommending anyone stop taking tadalafil. Instead, their message is more about awareness: men who use these medications regularly, especially long-term, should consider routine eye exams so that any changes in eye pressure or early glaucoma signs can be caught before they progress.
The takeaway: if you're on tadalafil or a similar medication long-term, it's worth a conversation with your doctor about adding regular eye checkups to your routine. Glaucoma is manageable when caught early — but silent when it isn't.
This article is for informational purposes only and isn't a substitute for medical advice. Talk to your doctor before making any changes to your medication.