The popular male pattern baldness drug finasteride, known commercially as Propecia, may have negative effects on sexual function months or years after a man has stopped taking it, according to a small new study.
Propecia already comes with warnings of sex-related side effects, such as problems with ejaculation and orgasm, but the study shows that these effects might still be affecting men after they're off the drug. The research is published in the Journal of Sexual Medicine.
The study included 54 men who experienced sexual problems at least three months after stopping Propecia. The researchers found that 89 percent of them had sexual problems severe enough to be considered to have sexual dysfunction.
TIME reported that for 96 percent of men who took Propecia and then stopped, sexual side effects continued on more than a year later.
Therefore, "prescribers of finasteride and men contemplating its use should be made aware of the potential adverse medication effects," researchers wrote in the study.
"Our findings make me suspicious that this drug may have done permanent damage to these men," study researcher Dr. Michael Irwig, of George Washington University, told ABC News. "The chances that they will improve? I think it's lower and lower the longer they have these side effects."
However, Irwig noted that because he enlisted study participants from a website where people report sexual problems from Propecia, it's possible that his study sample contained a disproportionate number of people severely affected by the drug, ABC News reported. And overall, he noted that the total number of people who will even have these kinds of side effects is low, or about 3 percent.
Earlier this year, the FDA required labels to be added to Propecia and Proscar -- which also contains finasteride, and is used to treat enlarged prostate -- warning of sexual side effects, Reuters reported.
Reuters reported the specific side effects listed that are associated with the drugs:
The Propecia label will now include notification of problems with libido, ejaculation and orgasms that continued after use of the drug was ended. Proscar's label will include notification of decreased libido. The labels of both drugs will also include a description of reports of male infertility and poor semen quality that normalized or improved after use of the drugs was stopped.
MSNBC noted that men should talk to their doctors first before stopping use of Propecia.
Most men who take a drug for hair growth are doing so for self-esteem and to be more attractive. But is that benefit worth the risk of possible sexual problems? This is an important decision that should be discussed with your doctor and your partner.
Propecia is just one of several options for treating male pattern baldness, and one of two FDA-approved baldness medications. According to the National Institutes of Health, it works by stopping the body's production of the baldness-promoting hormone. However, baldness begins again when a person stops using the drug.
The other medicine for baldness is Rogaine, which is actually applied to the scalp to slow down baldness. But just like Propecia, the baldness returns when you stop using it, according to the NIH.
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