Finasteride or Minoxidil: What Is the Difference
Finasteride and minoxidil are the two drugs with the strongest evidence base for treating androgenetic alopecia. They are often mentioned together, but they work on opposite “ends” of the problem: one curbs the hormonal cause of hair loss, the other stimulates the hair follicle itself. The editorial team explains what the difference is and why these agents are not interchangeable.
Two drugs — two different approaches
Androgenetic alopecia is the most common form of hair loss in men and a fairly frequent condition in women. It is rooted in a genetically determined sensitivity of the follicles on the crown and in the frontal areas to dihydrotestosterone (DHT). Under its influence, the follicles gradually miniaturize: the growth phase (anagen) shortens, the hair becomes thinner and lighter, and eventually stops emerging above the surface of the skin.
Finasteride intervenes in this process at the hormonal level — it reduces the formation of DHT. Minoxidil does not affect hormones: it acts directly on the follicle, prolonging the growth phase and increasing the diameter of the hair. That is why finasteride is loosely called an agent that “halts” progression, while minoxidil is one that “drives” growth.
The history of both drugs is similar: both came to dermatology from other fields of medicine. Minoxidil was initially used orally as a potent vasodilator for severe hypertension, and hypertrichosis (excessive hair growth) was one of its side effects. Finasteride was created to treat benign prostatic hyperplasia at a dose of 5 mg, and later a 1 mg dose was registered for hair loss.
Their regulatory status also differs. Finasteride is a prescription drug taken orally, registered for treating hair loss only in men. Minoxidil in the form of a 2% and 5% solution or foam is available over the counter in many countries and is approved for both men and women.
How finasteride works
Finasteride is a competitive inhibitor of type II 5-alpha-reductase. This enzyme converts testosterone into DHT in the prostate, hair follicles and skin. By blocking it, the drug at a dose of 1 mg per day lowers serum DHT levels by roughly two-thirds, and in the scalp skin — also substantially.
Since there is less DHT, the follicles on the crown receive a weaker “signal to miniaturize.” The balding process slows or stops, and some miniaturized follicles may partially recover. The effect develops slowly: the first changes are assessed no earlier than 3–6 months, and the full response — after a year.
Importantly, finasteride does not affect follicles that have already died completely and been replaced by connective tissue. That is why it works best in the early stages, when hair is still present but thinning. The effect persists only during treatment: after discontinuation, the process gradually returns to its original pace.
Systemic action is the main difference between finasteride and minoxidil. The drug changes the hormonal balance throughout the body: blood testosterone levels usually rise slightly, and prostate-specific antigen (PSA) drops by about half. The latter must be taken into account during prostate cancer screening.
How minoxidil works
Minoxidil is a prodrug: its active form is minoxidil sulfate, which is formed with the participation of the enzyme sulfotransferase in the hair follicles. The activity of this enzyme varies between people, and this partly explains why some respond to treatment well while others hardly at all.
The exact mechanism of hair growth stimulation is still not fully understood. It is believed that minoxidil sulfate opens ATP-dependent potassium channels in cells, enhances blood supply to the follicle, stimulates the production of vascular endothelial growth factor and prolongs the anagen phase. As a result, thin “vellus” hair can turn into thicker terminal hair.
At the start of use, increased shedding is often observed — the so-called “shedding” phase. Follicles that were in the resting phase synchronously move into a new growth phase, pushing out the old hairs. This is a temporary phenomenon that does not indicate the drug is ineffective.
As with finasteride, the effect of minoxidil depends on continuous use. After application is stopped, the hair that grew thanks to the drug falls out over several months, and the picture returns to the state it would have been in without treatment.
In recent years, dermatologists have increasingly discussed low-dose oral minoxidil. Reviews (Randolph, Tosti, 2021) point to its effectiveness, but this is an off-label use that requires medical monitoring of blood pressure, pulse and edema.
Effectiveness according to research data
The effectiveness of finasteride 1 mg for men has been confirmed by large-scale randomized trials, in particular the work of Kaufman and co-authors (1998): over two years the drug increased the number of hairs and stopped visible progression of baldness in the majority of participants compared with placebo. Long-term observations have shown that the effect persists for years provided the drug is taken continuously.
For topical minoxidil, the classic study is that of Olsen and co-authors (2002), in which the 5% solution in men outperformed the 2% solution and placebo in hair growth, and the response developed faster. A meta-analysis by Adil and Godwin (2017) confirmed the superiority over placebo of both minoxidil and finasteride.
Direct “head-to-head” comparisons are few, and their results depend on the design. The European S3 guideline (Kanti et al., 2018) recommends both drugs as first-line agents for men, and topical minoxidil for women. For practical purposes something else matters more: the drugs can be combined, because their mechanisms do not overlap.
| Parameter | Finasteride | Minoxidil (topical) |
|---|---|---|
| Target | Type II 5α-reductase, DHT level | Hair follicle, growth phase |
| Form | Tablets 1 mg (for hair loss) | Solution or foam 2% / 5% |
| Action | Systemic | Predominantly local |
| Approved for whom | Men | Men and women |
| Assessment of effect | After 6–12 months | After 4–6 months |
| After discontinuation | Baldness resumes | Grown hair falls out |
Thus, finasteride is stronger at stabilizing the process, especially on the crown, while minoxidil is stronger at stimulating new growth. Neither of them restores hair on completely bald areas where follicles are no longer present.
Side effects and safety
The safety profiles of the drugs differ, as do their mechanisms. With finasteride, side effects are related to hormonal action; with topical minoxidil — mainly to the skin and, less often, to systemic absorption.
- Finasteride:decreased libido, erectile dysfunction, reduced ejaculate volume in a small proportion of men; tenderness or enlargement of the mammary glands; reports of mood changes. Prescribing information in the US and EU includes warnings about depression and, in post-marketing data, persistent sexual symptoms after discontinuation.
- Topical minoxidil:itching, flaking and reddening of the skin (often due to propylene glycol in the solution), unwanted hair growth on the face, especially in women; rarely — palpitations, dizziness, edema.
Finasteride is contraindicated in women who are pregnant or may become pregnant: the drug can disrupt the development of the genital organs of a male fetus. Pregnant women should not handle crushed or damaged tablets. Minoxidil is also not used during pregnancy and breastfeeding.
The sporting context is worth mentioning separately. In 2005–2008, finasteride was on the WADA Prohibited List as a masking agent, but it was removed in 2009; minoxidil is not on the list. The current list should be checked each time on the WADA website.
In people who use androgens outside of medical indications, baldness often accelerates. Neither finasteride nor minoxidil neutralizes the risks of such drugs, and some synthetic androgens do not require 5-alpha-reductase at all, so counting on “protection” of the hair is unwarranted.
Editorial conclusions
Finasteride and minoxidil are not competitors but tools with different points of application. The first curbs the hormonal mechanism of baldness, the second stimulates the follicle directly.
Finasteride acts systemically and has hormonal side effects, so it requires a prescription and discussion with a doctor. Minoxidil acts mainly locally, is available to women too, but requires daily discipline.
Both drugs work only as long as they are used, and best of all — in the early stages. Therefore the editorial team’s main advice is: do not delay seeing a specialist as soon as you notice hair thinning.
To get a sense of which option suits you, read our article “Finasteride vs Minoxidil: What to Choose and for Whom,” as well as articles on the effect of androgens on hair and on the tests for monitoring hormonal levels.
References
- Kaufman KD, Olsen EA, Whiting D, et al. Finasteride in the treatment of men with androgenetic alopecia. J Am Acad Dermatol. 1998;39(4 Pt 1):578–589.
- Olsen EA, Dunlap FE, Funicella T, et al. A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men. J Am Acad Dermatol. 2002;47(3):377–385.
- Adil A, Godwin M. The effectiveness of treatments for androgenetic alopecia: a systematic review and meta-analysis. J Am Acad Dermatol. 2017;77(1):136–141.
- Kanti V, Messenger A, Dobos G, et al. Evidence-based (S3) guideline for the treatment of androgenetic alopecia in women and in men – short version. J Eur Acad Dermatol Venereol. 2018;32(1):11–22.
- Messenger AG, Rundegren J. Minoxidil: mechanisms of action on hair growth. Br J Dermatol. 2004;150(2):186–194.
- Randolph M, Tosti A. Oral minoxidil treatment for hair loss: a review of efficacy and safety. J Am Acad Dermatol. 2021;84(3):737–746.
- World Anti-Doping Agency. The Prohibited List. Montreal: WADA; щорічне видання.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
