A large Taiwan-led study has found that long-term users of Cialis, a common drug for erectile dysfunction and the prostate, have an elevated risk of glaucoma — a health warning worth noting for the millions of men who take it.

• The Taiwanese team analysed data from more than 70,000 men aged 40 and over and found that those using tadalafil (Cialis) had a 22% higher risk of glaucoma.
• The drug was originally used to treat erectile dysfunction, and it can also relieve the frequent and urgent urination caused by an enlarged prostate.
• Users had a 32% higher risk of raised intraocular pressure and a 33% higher risk of primary open-angle glaucoma.
• The study only retrospectively compared medication use against cases, so it can reveal an association but cannot prove that the drug directly causes glaucoma.
• The research team said there is no need to stop taking the drug because of this, but people with glaucoma, high intraocular pressure, a family history, or high myopia may want to consider regular eye examinations.

Outlook: Further studies may follow to clarify the causal relationship, and eye monitoring could become a recommended measure for those on this kind of long-term medication.