A common drug used to treat male hair loss and lower urinary tract symptoms may also cause some men’s desire to go limp, according to a study published in the Journal of Sexual Medicine and conducted by researchers at Boston University School of Medicine.

The class of drugs in question are 5a-reductase inhibitors (5a-RIs) and include finasteride (Propecia) and dustasteride (Avodart). Docs commonly prescribe them to improve urinary symptoms in patients with enlarged prostates and to treat androgenetic alopecia, a form of hair loss. But prolonged use of these drugs may cause unwanted sexual side effects and depression.

Researchers examined data from various clinical studies concerning the side effects of the drugs and found that susceptible male patients experienced diminished sexual desire and erectile dysfunction after prolonged use.

“Furthermore, treatment of hair loss, a benign condition, with 5a-RIs may produce persistent side effects in a number of young patients,” said Abdulmaged M. Traish, MBA, PhD, a professor of biochemistry and professor of Urology at Boston University School of Medicine.

Specifically, men might experience depression and breast enlargement (gynecomastia). These unknown side effects can take a long-term emotional toll on patients and can lead to a decreased quality of life, researchers said. But the full extent of the meds’ side effects has remained unstudied.

The study researchers recommend that doctors explain all the possible outcomes with patients before deciding on a particular treatment. This is so important because these adverse effects may be persistent and prolonged, with some patients unable to recover even after discontinuing the drugs, Traish said.

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