Information and Solutions for Men and Women

What Are 5-Alpha-Reductase Inhibitors?

5-alpha reductase inhibitors may help treat male and female pattern hair loss.

Research indicates that synthetic pharmaceutical and natural herbal 5α-reductase inhibitors may help inhibit common androgenetic balding in men and female pattern hair loss in women. 30 These include:

  • Dutasteride, also known by the brand name Alodart®
  • Finasteride, also known by the brand name Propecia®
  • Saw palmetto, a natural herb

Both finasteride and dutasteride were originally manufactured and prescribed to treat benign prostate hyperplasia (BPH), a common condition that causes prostate enlargement in older men. These drugs work to treat BPH by inhibiting one or both types of the 5α-reductase enzyme in the prostate. Studies support the effectiveness of both drugs in most men for androgenic hair loss, as well as some women with androgenic hair loss. According to at least one study, oral finasteride may even work better than 5% topical minoxidil. However, minoxidil may be less expensive and its safety for long-term use is well-established. Treatment must be continuous in order to maintain the hormone-blocking effects of these drugs.3

These drugs are not recommended for women are or might become pregnant, however. 5α-reductase enzyme inhibitors can cause serious birth defects, and the U.S. Food and Drug Administration specifically warns against use or even handling of these drugs by women fit in this category.81, 197 In fact, they are so potent that some doctors recommend that a woman who wants to become pregnant stop taking 5α-reductase enzyme inhibitors and avoid possible pregnancy for at least six months after stopping.22

Saw palmetto is a short palm tree native to North American Atlantic coast. Native American Indians used the tree’s leaf fibers for many household purposes, and the berries for food and medicine.96 Saw palmetto was traditionally a natural herbal remedy for a variety of health conditions caused or affected by androgen sex hormones — including prostate enlargement, male infertility and sexual function, and increasing female breast size. 198 Lab and clinical studies demonstrate that saw palmetto works like finasteride.96

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Specifically, they may cause abnormalities to external genitalia in male fetuses.