Topical finasteride: how effective? how safe? how smart?
We have recently entered a whole new era of what I call the Era of Finasteride Frenzy. Anecdotal reports of possible persistent side effects have caused many physicians and patients to change their views on the drugs and some to even abandon it. The FDA and Health Canada has modified its labelling of the drug to convey the uncertainties to the public.
Some of these issues have been discussed in other blogs of mine. Today I'll talk about the solution some have taken to overcome or get around the issues of oral finasteride side effects - a move to topical finasteride
Topical Finasteride: Is it safe? effective?
First off, topical finasteride is not FDA approved for hair loss in men. Any use of topical finasteride in men is "off label". I'm going to limit all discussions here to men as use in women is not FDA approved for the oral form.
Does it get absorbed?
Yes, it gets absorbed into the blood. Any discussion that topical finasteride is too big of a molecular to get into the skin is wrong. Topical finasteride enters into the blood. And yes - it lowers DHT levels.
But any discussion of topical finasteride must focus on the dose. 2 % finasteride topical solution is going to have different effects than an 10 % solution. 0.25 % finasteride is going to be different yet! If I were to make up 0.0000000001% finasteride topical solution, it would likely be quite safe with little if an absorption. However, it probably wouldn't do anything for patients with hair loss. So it comes down to dose. Plain and simple. One should not talk about topical finasteride unless they are prepared to talk about the dose
Studies of topical finasteride: Important Lessons
A recent study of 0.25 % topical finasteride showed that it reduced DHT levels to the same amount as standard 1 mg finasteride pills. We don't yet have any data to know if this translates into topical finasteride working just as good or being just as effective, worse or better.
What about side effects?
We don't yet understand the side effects of topical finasteride. It's likely that 10 % topical finasteride is going to have more side effects than 1 % topical finasteride. But those studies need to be done and confirmed. If sexual performance and mood levels are related to DHT in the blood, then it's pretty likely that lots of men using topical finasteride would be expected to have side effects too. These studies have not been done and so we don't know.
For hair loss in men, it appears that getting a good benefit from finasteride ultimately comes down to inhibiting DHT. Inhibit it more and you'll get a better outcome for hair loss. You'll get more side effects too.
Topical finasteride doesn't just stay in the scalp. It gets into the blood and inhibits DHT. Side effects are possible with topical finasteride. We need to be very careful assuming topical means safer. The scalp is a wonderful way to get drugs into the body.
A novel finasteride 0.25% topical solution for androgenetic alopecia: pharmacokinetics and effects on plasma androgen levels in healthy male volunteers.Caserini M, et al. Int J Clin Pharmacol Ther. 2014.
Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Vancouver office at 604.283.9299