March 9, 2011 -- Medications that shrink enlarged prostates and treat male pattern baldness can have sexual side effects that may persist after the drugs are discontinued, a new research review suggests.
But a manufacturer of one of the drugs says side effects go away when patients stop taking the drug. And an independent expert is skeptical of the study’s results.
The drugs, called 5-alpha-reductase inhibitors, block the action of the hormone dihydrotestosterone (DHT), an androgen that’s more potent than its precursor, testosterone.
This class of medications includes Avodart, Propecia, and Proscar.
According to the new review, which is published in the Journal of Sexual Medicine, long-term studies show that these medications can help shrink an enlarged prostate, a condition that affects as many as half of men over age 60, within three months to two years of use.
In other studies, about half of men who were taking Propecia for hair loss regrew some hair, while 42% saw no further hair loss, compared to those taking a placebo pill.
Additionally, a handful of studies have suggested that these kinds of drugs may lower the risk of prostate cancer, though that benefit is still controversial.
But the review says less attention has been paid to uncommon but potentially devastating side effects of these medications.
Those side effects can include anxiety, depression, loss of sex drive, difficulty getting or maintaining and erection, gynecomastia (growth of male breast tissue), and reduced semen production, which may affect fertility.
What’s worse is that for some, these side effects persist, even when they stop taking the medication, according to the review.
“We don’t really understand why, but the symptoms remain persistent or irreversible and even if they get off the drug,” says study researcher Abdulmaged M. Traish, PhD, a professor of biochemistry at the Boston University School of Medicine. “They no longer regain what they had before. Biologically, something gets shut off and gets shut off once and for all.”
Traish thinks that may be because nerves that are maintained by dihydrotestosterone become permanently degraded and can’t be repaired even after men come off the medication.