According to the Mayo Clinic, Nizoral is a shampoo used in the treatment of fungal infections of the scalp. It's also used to treat dandruff. However, the American Hair Loss Association claims that it may also be used in the treatment of female-pattern baldness, also known as androgenetic alopecia.
Androgenetic alopecia is a condition characterized by excessive hair loss that leads to baldness in women. It's caused by high levels of 5-alpha-reductace, an enzyme that causes testosterone to convert into DHT, or dihydrotestosterone. DHT is an androgen that attaches to the follicles of the scalp. This causes miniaturization or shrinkage of the follicle, shortening the growth cycle of the hair. This eventually leads to thinning and then baldness.
Besides working as an antifungal agent, the active ingredient of ketoconazole also has anti-androgenic effects on the scalp, according to the American Hair Loss Association. This can reduce the production of testosterone in women. As testosterone levels decrease, you also experience a decline in DHT. Without testosterone, 5-alpha-reductace can no longer produce DHT, which means the follicles remain healthy and continue to produce hair.
Currently, Nizoral shampoo is available in two different formulas. The over-the-counter product contains a 1 percent concentration of ketoconazole. The prescription variety is made with a 2 percent concentration of the active ingredient. While either concentration can benefit women suffering from female-pattern baldness, the American Hair Loss Association indicates that the prescription strength is far more effective.
Nizoral shampoo isn't usually used as the sole treatment to encourage hair growth in women. Most of the time, a dermatologist recommends using other medications to treat hair loss, such as minoxidil, spironolactone or cimetidine. It may also be used in conjunction with oral contraceptives or hormone replacement therapy when hair loss is attributed to hormonal issues.
While the American Hair Loss Association states that Nizoral causes no significant side effects, it's still possible to experience adverse reactions with regular use. The Mayo Clinic warns that topical ketoconazole can cause irritation of the scalp. This may manifest as sensations of itching, burning or stinging. Though rare, it may also produce hair loss in some people.