Personal care · lesson 7 of 10
Hair: what actually works
Name the type of hair loss first — then minoxidil, the prescription options, and the long list that mostly doesn't work.
8 min read · reviewed October 2026
Diagnosis before products
'Hair loss' covers several conditions, and the right response depends on which one you have:
- Pattern hair loss (androgenetic alopecia): gradual thinning at the temples and crown in men, or a widening part in women. By far the most common; genetic and hormone-driven, and it progresses without treatment.
- Telogen effluvium: diffuse shedding that starts a few months after a shock — high fever, surgery, childbirth, crash dieting, severe stress, some medicines. Usually recovers once the trigger passes.
- Alopecia areata: smooth, round bald patches caused by the immune system attacking follicles.
- Traction alopecia: thinning along the hairline from tight braids, ponytails or extensions — reversible early, permanent if it goes on for years.
- Scarring alopecias: inflammation that permanently destroys follicles, sometimes with itching, burning, redness or scale. These need a dermatologist quickly.
After a high fever, surgery or childbirth, noticeable shedding (telogen effluvium) usually starts about how many months later?
Somewhere between 0 and 12 months.
Reveal the answer →
~2–3 months
A shock pushes many follicles into their resting phase at once, and those hairs fall out roughly 2–3 months later — which is why people rarely connect the shedding to its cause. It usually settles within about 6 months once the trigger is gone. Shedding that lasts longer deserves a check for thyroid problems, iron deficiency or medication effects.
more hair regrowth with 5% topical minoxidil than with 2% after 48 weeks, in a randomized trial of 393 men — with more scalp itching and irritation at the higher strength.
Source: Olsen et al., Journal of the American Academy of Dermatology 2002
The options with real evidence
Topical minoxidil, available without a prescription, is the first-line product for pattern hair loss in both men and women. Finasteride, a prescription pill, works for men. Everything works only for as long as you keep using it.
How it works →
Minoxidil lengthens the growth phase of hair follicles and enlarges shrunken ones, though exactly how is still not fully understood. Expect a temporary increase in shedding in the first weeks, first results after about 4 months, and a fair verdict at 6–12 months. Stop, and the gains fade over the following months. Finasteride blocks the enzyme (5-alpha reductase type II) that converts testosterone into DHT, the hormone that shrinks scalp follicles in pattern hair loss. Low-dose oral minoxidil is a prescription, off-label option dermatologists increasingly use.
What the studies show →
Topical 5% minoxidil beat both 2% and placebo in men (Olsen et al., 2002). Finasteride 1 mg daily slowed hair loss and increased hair counts versus placebo in two one-year trials of 1,553 men, with benefits maintained in a second year (Kaufman et al., Journal of the American Academy of Dermatology 1998). Low-level laser devices are FDA-cleared, and several mostly industry-funded trials show modest density gains. Microneedling combined with minoxidil has small trials suggesting extra benefit. The popular rosemary-oil claim rests largely on one small trial comparing it with low-strength 2% minoxidil.
What mostly doesn't work
Biotin helps hair only if you're genuinely deficient, which is rare. High doses can also distort blood tests — including thyroid and troponin (heart attack) tests — which FDA has warned about. Tell your clinician before any blood work.
A shampoo sits on your scalp for a minute or two. Most growth claims rest on ingredients without controlled evidence. 'Thickening' shampoos can make hair look fuller by coating the strands — cosmetic, not regrowth. Ketoconazole shampoo has small studies hinting at a benefit in pattern hair loss, but its proven use is dandruff.
Unless you're low in something — iron, vitamin D, zinc, protein — there's little evidence extra nutrients grow hair. Too much vitamin A or selenium can actually cause hair loss.
No good evidence that product residue or 'toxins' clog follicles and cause pattern hair loss.
Scalp care that helps
Dandruff and seborrheic dermatitis are driven partly by an overreaction to Malassezia, a yeast that lives on everyone's scalp. Anti-dandruff shampoos with zinc pyrithione, selenium sulfide, ketoconazole, salicylic acid or coal tar have evidence — leave the lather on for a few minutes, and alternate two actives if one stops working. Wash as often as your scalp needs; daily is fine for an oily scalp.
Heat styling and bleaching damage the hair shaft, and tight styles strain the follicle. Conditioner reduces breakage by cutting friction.
Which of these has the strongest evidence for regrowing hair in pattern hair loss?
- High-dose biotin
- A caffeine 'growth' shampoo
- Topical minoxidil
- A collagen supplement
Show the answer →
C.Topical minoxidil
Topical minoxidil has randomized, placebo-controlled trials in both men and women and is approved without a prescription for pattern hair loss. Biotin helps only if you're deficient, and most growth shampoos and collagen supplements lack controlled evidence.
Hair loss from deficiency is real but uncommon. The Nutrients track covers iron, vitamin D, zinc and protein — who genuinely runs low, and why megadoses don't help.