Ketoconazole has an anti-fungal effect. (Photo by Benimoto)
Ketoconazole, a synthetic antifungal drug, is the active ingredient in Nizoral shampoo. It's marketed as an anti-dandruff shampoo due to FDA regulations, but some studies suggest it may also stimulate hair growth.
Probably the most often quoted study is the one by Jiang et al., though no one seems to have read the actual paper. The authors applied topical ketoconazole on the backs of mice to see whether hair growth was affected. I, too, was unable to get a hold of the paper, since it originally appeared in a Japanese journal, but at least the abstract is available:
Topical application of ketoconazole stimulates hair growth in C3H/HeN mice
Ketoconazole (KCZ) is an imidazole anti-fungal agent that is also effective in topical applications for treating seborrheic dermatitis and dandruff. Recently, topical use of 2% KCZ shampoo has been reported to have had a clinically therapeutic effect on androgenetic alopecia. The present study was conducted with the purpose of quantitatively examining the stimulatory effect of KCZ on hair growth in a mouse model.
Coat hairs on the dorsal skin of seven week-old male C3H/HeN mice were gently clipped, and either 2% KCZ solution in 95% ethanol or a vehicle solution was topically applied once daily for three weeks. The clipped area was photographed, and the ratio of re-grown coat area was then calculated.
The results demonstrated that 2% KCZ had a macroscopically significant stimulatory effect compared with the vehicle group. Repeated experiments showed similar effects, confirming the efficacy of KCZ as a hair growth stimulant. Although the therapeutic mechanism of topical KCZ for hair growth is unclear, our results suggest that topical applications of the substance are useful for treating seborrheic dermatitis accompanied by hair regression or male pattern hair loss.
It's not entirely clear how much more hair the ketoconazole group grew compared to the control group, but there was a stimulatory effect nonetheless. The authors also point out that, like with minoxidil, the mechanism of ketoconazole for hair growth is still unclear.
Now, a 2% ketoconazole solution in 95% is not the same thing as a ketoconazole shampoo such as Nizoral (there are generic and often cheaper brands with as well). However, most ketoconazole shampoos are actually available in a 2% version, which means that the products contain the same amount of ketoconazole as was used in the study; only the carrier is different.
For some people, 2% is too strong and irritates the skin. In these cases, the lighter 1% version is recommended. Though once a week is recommended to prevent dandruff, many people have used ketoconazole products daily without problems. Personally, I haven't seen any adverse effects from using one twice a week.
Ketoconazole shampoos are a bit expensive, but unlike a lot of other hair loss remedies, it may actually be worth the money. This study, and others that I will post about in upcoming posts, suggests that not only does ketoconazole prevent dandruff, it can also increase hair growth through mechanisms not yet known. There's also quite a lot of anecdotal evidence of ketoconazole's effectiveness in male pattern hair loss, which explains why Nizoral is often listed among the so-called "Big 3" of hair loss treatments, along with Finasteride and minoxidil.
For more information on hair growth, see these posts:
2% Nizoral Shampoo Increases Hair Growth in Men with Male Pattern Baldness
2% Nizoral Shampoo Increases Hair Growth More than 2% Minoxidil
Hair Growth Battle: Emu Oil vs. Hair Again® Topical Gel
Chinese Hibiscus Leaf Extract Increases Hair Growth in Mice
How I Accidentally Grew Hair on My Left Temple with Retinol