Recent studies have linked the popular hair loss treatment Propecia to sexual dysfunction.

The main ingredient in Propecia is finasteride, which is used to treat androgenic alopecia, commonly referred to as male-pattern baldness.

Finasteride is also used in a larger dose, marketed under the name Proscar, to treat enlarged prostate. Both pharmaceuticals have been found to impact erectile function.

Researchers at Boston University School of Medicine studied a group of 700 men over the course of four years, in order to compare those taking finasteride (Proscar, Propecia) with those taking Flomax (tamsulosin) for enlarged prostate treatment.

The researchers recorded prostate improvement as well as testosterone levels, and discovered that those taking finasteride experienced a significant decline of erectile function and a decrease in testosterone levels. The study found that those taking Flomax did not experience similar sexual side effects.

In a separate study performed at Boston University School of Medicine, researchers discovered that 15 percent of men taking Propecia reported erectile dysfunction and decreased libido. However, there have been other medical studies that suggest sexual dysfunction side effects occur in 39 percent of Propecia consumers.

More than one million men take a form of finasteride in the U.S., either through Proscar or Propecia.

Propecia Sexual Dysfunction

The U.S. Food and Drug Administration approved Propecia as a hair loss medication shortly after it approved Proscar to treat benign prostate hyperplasia (enlarged prostate).

Propecia works by blocking enzymes in the scalp and sexual organs that convert testosterone into the sex steroid dihydrotestosterone (DHT). Studies have found that Propecia is an effective hair loss treatment in 50 percent of cases. 

However, researchers in multiple studies have found that if the active ingredient finasteride does not convert testosterone correctly, Propecia side effects could include erectile dysfunction and other sexual side effects.

Those who experience sexual dysfunction as a Propecia side effect report that discontinuing the hair loss drug resolves the issue only half of the time.

Other commonly reported Propecia side effects include depression, breast cancer, and prostate cancer.

Propecia Lawsuits

More than 1,200 Propecia sexual dysfunction lawsuits have been filed so far, with many plaintiffs alleging that Propecia’s manufacturer Merck intentionally concealed the sexual side effects from the medical community and the general public.

Plaintiffs are inclined to believe that Merck was aware of the possibility of sexual dysfunction since at least 2008, as that is when the company began adding a sexual dysfunction warning to Propecia sold in Sweden. This occurred four years before the FDA required Propecia sold in the U.S. to carry a similar warning.

In general, plaintiffs filing Propecia lawsuits claim they were not adequately warned that taking the hair loss medication would result in a loss of sex drive or cause erectile dysfunction. Spouses can also join Propecia lawsuits as co-plaintiffs and sue for loss of consortium, which is the loss of intimacy with their partner.

Some men may choose to join a Propecia class action lawsuit, which can be a discreet way to obtain financial compensation for any damages caused by taking the hair loss treatment.