In short: Topical finasteride blocks DHT the same way the pill does, but with far lower levels of the drug in your bloodstream — roughly 100 times lower in the one large controlled trial. Lower is not zero: some men still get side effects. And because most of it comes from compounding pharmacies, "topical finasteride" is not one product; formulations, concentrations and add-in ingredients vary from one pharmacy to the next.
Topical finasteride is one of the topics I'm asked about every single day. It started years ago when a few clinics began claiming that topical finasteride had no side effects and worked about as well as the oral version. Before any product existed, people on forums were crushing up finasteride tablets and stirring them into their minoxidil, with zero evidence that a home-made mix would do anything at all. Then compounding pharmacies started offering it, around 2012, and every claim you can imagine followed. Below are the three I hear most, and what's actually true.
What is topical finasteride?
Topical finasteride is finasteride — the same 5-alpha-reductase inhibitor sold as Propecia — dissolved in a liquid, gel or spray and applied to the scalp instead of swallowed. The goal is to lower DHT in the scalp, where it drives pattern hair loss, while keeping less of the drug in circulation than a daily 1 mg tablet produces. Outside of a handful of countries where a licensed 0.25% spray exists, it is made to order by compounding pharmacies, which is where most of the confusion comes from.
Does topical finasteride have no side effects?
No. This is stated by plenty of websites, clinics and doctors, and it is untrue. I hear from men who have had side effects on topical finasteride, ranging from mild to serious. Once the medication absorbs through the skin it can and does "go systemic" — it reaches your bloodstream and can act everywhere oral finasteride acts.
What the evidence does support is less systemic exposure. In the largest controlled trial to date — 458 men over 24 weeks, using a 0.25% spray — peak plasma finasteride averaged about 37 pg/mL with the topical versus about 7,200 pg/mL with the 1 mg tablet. Serum DHT fell about 35% with the topical and about 56% with oral. Sexual side effects were reported by 2.8% of the topical group, 3.3% of the placebo group and 4.8% of the oral group — a difference small enough that the trial couldn't call it meaningful. Hair counts at 24 weeks were about the same for topical and oral. Note that the trial was funded by the company that makes the spray, and it studied one specific formulation, not the compounded products most people are actually using.
So the honest version of Myth #1 is: the risk is probably lower, it is not gone, and nobody can tell you your personal risk from a compounded formula that has never been in a trial.
Are all topical finasteride formulations the same?
No two formulations from different sources are alike, and I get asked about "the standard" constantly — there isn't one. Most compounded versions combine finasteride with minoxidil at 2.5%, 5%, 10% or even 15%. Some add latanoprost, the active ingredient in Latisse, originally for eyelash growth. Some add caffeine, tretinoin (retinol A), or azelaic acid. The finasteride concentration itself varies. The combinations are vast, and so are the prices. When someone tells you "topical finasteride worked for me" or "gave me side effects," ask what was actually in the bottle, because it may have little in common with what you'd be prescribed.
Can you only get it from a few clinics?
This one bothers me most, because it's used to steer patients. The myth is that only a few doctors, clinics or pharmacies can supply topical finasteride. The truth is that it is available in every US state, every Canadian province, and most of Europe. You need a prescription, and you need a compounding pharmacy — but it does not have to be the pharmacy a clinic points you to, and it does not have to be that clinic's doctor who writes the script. If your local compounding pharmacy doesn't stock it they can still make it; it may cost more in small batches, but it's wide open.
Should you use topical or oral finasteride?
That's a conversation for you and a physician who knows your history, not a decision to make from a forum thread. What I'd want you to walk in knowing: oral finasteride has 25 years of data behind it; topical has one good trial of one licensed product and a lot of compounded variants with none. If you've had side effects on oral, topical is a reasonable thing to discuss. If you're choosing topical purely because you've been told it's side-effect-free, you've been misinformed.
The video below is the class where I first walked through these three myths.
One thing holds true for any topical, finasteride included: it only works if it actually reaches the scalp and you keep using it. If the routine is what makes you skip days, a dedicated applicator like the Rootique Duo is worth a look. Full disclosure: I am Rootique's global brand ambassador, so weigh that as you see fit.
Sources
- Piraccini BM, et al. Efficacy and safety of topical finasteride spray solution for male androgenetic alopecia: a phase III, randomized, controlled clinical trial. J Eur Acad Dermatol Venereol. 2022;36(2):286-294. PubMed
- Caserini M, et al. A novel finasteride 0.25% topical solution for androgenetic alopecia: pharmacokinetics and effects on plasma androgen levels in healthy male volunteers. Int J Clin Pharmacol Ther. 2014;52(10):842-849. PubMed
- Propecia (finasteride 1 mg) prescribing information, U.S. Food and Drug Administration. Drugs@FDA, NDA 020788
This article is educational and reflects my experience as a patient and patient advocate. It is not medical advice. Finasteride is a prescription medication; talk to a licensed physician before starting, stopping or changing any hair loss treatment.
First published April 2018. Last reviewed and updated by Joe Tillman, September 2026.