0 Side Effects of Propecia

Side effects of finasteride include impotence (1.1% to 18.5%), abnormal ejaculation (7.2%), decreased ejaculatory volume (0.9% to 2.8%), abnormal sexual function (2.5%), gynecomastia (2.2%), erectile dysfunction (1.3%), ejaculation disorder (1.2%) and testicular pain. According to the product package insert, resolution occurred in men who discontinued therapy with finasteride due to these side effects and in most men who continued therapy. In December 2010, Merck acknowledged that depression is a side effect of Finasteride.

In December 2008, the Swedish Medical Products agency concluded a safety investigation of Propecia and subsequently advised that the use of Propecia may result in irreversible sexual dysfunction. The Agency's updated safety information lists difficulty in obtaining an erection that persists indefinitely, even after the discontinuation of Propecia, as a possible side effect of the drug. The UK's Medical and Healthcare Products Regulatory Agency (MHRA) say that erectile dysfunction that persists once use of Propecia has stopped has been reported to them. Similar labeling changes have been made by the Italian government. While European product warnings have been updated to warn of the possibility for permanent sexual dysfunction, the warnings remain unchanged in North America and currently state that sexual side effects are reversible.

Thousands of former finasteride users have reported permanent sexual side effects as a consequence of taking finasteride, despite discontinuing treatment with the drug. A recent literature review was published in the Journal of Sexual Medicine that states "clearly the sexual side adverse events do not resolve in all patients who discontinue use of finasteride." A 2003 double-blind, placebo controlled experiment for treatment of BPH showed that sexual side effects were more common with drug than placebo in the first year of treatment. Four percent of patients on finasteride and two percent of patients on placebo withdrew from treatment due to sexual adverse events. 50 percent of the patients on finasteride that withdrew and 59 percent of the patients on placebo that withdrew demonstrated persistent sexual side effects despite discontinuation of the treatment.

Finasteride is in the FDA pregnancy category X. This means that it is known to cause birth defectsin an unborn baby. Women who are or who may become pregnant must not handle crushed or broken finasteride tablets, because the medication could be absorbed through the skin. Finasteride is known to cause birth defects in a developing male baby. Exposure to whole tablets should be avoided whenever possible, however exposure to whole tablets is not expected to be harmful as long as the tablets are not swallowed.

It is not known whether finasteride passes into breast milk, and thus should not be taken by breastfeeding women. Finasteride may pass into the semen of men, but Merck states that a pregnant woman's contact with the semen of a man taking finasteride is not an issue for concern.

Finasteride is known to affect blood donations, and potential donors are typically restricted for at least a month after their most recent dose.

Many sports organizations have banned finasteride because it can be used to mask steroid abuse. Since 2005, finasteride has been on the World Anti-Doping Agency's list of banned substances. However, it was removed from the list in 2009. Notable athletes who used finasteride for hair loss and were banned from international competition include skeleton racer Zach Lund,bobsledder Sebastien Gattuso, footballer Romário and ice hockey goaltender José Théodore.

In December 2009, the Medicines and Healthcare products Regulatory Agency in the UK announced new drug safety advice on finasteride and the potential risk of male breast cancer. The agency concluded that, although overall incidence of male breast cancer in clinical trials for finasteride 5 mg was not significantly increased, a higher risk of male breast cancer with finasteride use cannot be excluded. A warning on this risk will be included in the product information.