What causes pattern hair loss?
The enzyme type 2 5-alpha reductase converts testosterone into the more potent dihydrotestosterone (DHT). In genetically sensitive scalp follicles, DHT shortens the growth phase and shrinks the follicle, turning thick terminal hairs into fine, short vellus-like hairs. Family history is a major risk factor, and both men and women can be affected.
How it progresses
- Male pattern: starts at the temples (an M-shaped hairline) and crown, staged on the Norwood-Hamilton scale.
- Female pattern: the front hairline usually stays, while the part at the top of the head widens; the Ludwig scale is often used.
Alopecia areata, telogen effluvium after childbirth, high fever or crash dieting, thyroid disease and iron deficiency have different causes and treatments, so a dermatologist should sort them out.
Which hair loss treatments actually work?
- Minoxidil (topical): extends the growth phase. In a randomized controlled trial of 393 men, 5% minoxidil produced 45% more regrowth than 2% after 48 weeks.
- Finasteride (oral, men): lowers DHT production. In a trial of 1,553 men, hair count in a 1-inch circle at the crown was 138 hairs higher than placebo after two years. Sexual side effects such as lower libido are reported in some men, and women who are or may become pregnant shouldn't handle it.
- Other options: dutasteride, low-level laser therapy and hair transplants are also used.
You need at least 3–6 months of consistent use to judge results, and hair loss resumes if you stop.
Supplements and ads
Except in rare cases of actual deficiency, there's little evidence that supplements like biotin help hair loss in healthy people. Hair-loss ads lean heavily on testimonials, so it pays to check the evidence—see misinformation and confirmation bias. Trials also show a sizable placebo response.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Can women use minoxidil?
- Yes. Topical minoxidil is FDA-approved for women with pattern hair loss and is a common first-line option; finasteride is generally not used in women who could become pregnant.
Sources reviewed: 2026-10-25
References
- Kaufman, K. D., et al. (1998). Finasteride in the treatment of men with androgenetic alopecia. Journal of the American Academy of Dermatology, 39(4), 578–589.
- Olsen, E. A., et al. (2002). A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men. Journal of the American Academy of Dermatology, 47(3), 377–385.
- Patel, D. P., Swink, S. M., & Castelo-Soccio, L. (2017). A review of the use of biotin for hair loss. Skin Appendage Disorders, 3(3), 166–169.