Hair Loss: What Actually Works, What Doesn't, and When to See a Dermatologist

Hair loss is one of the most heavily marketed health worries there is: shampoos, serums, gummies, oils, caps and clinics, most promising “regrowth”. The treatments with real evidence behind them are few, well-studied, and less glamorous — and each of them only works for the right type of hair loss.

This guide starts with the types, because that decides everything else. Then it covers what works for the most common one, pattern hair loss, with honest notes on side effects and who funded the studies; what doesn’t work; which shampoos actually have evidence (for dandruff, not regrowth); and when to see a dermatologist.

First, what kind of hair loss is it?

Losing 50–100 hairs a day is normal. Beyond that, the main patterns are:

• Pattern hair loss (androgenetic alopecia). By far the most common. Follicles gradually shrink under the influence of the hormone dihydrotestosterone (DHT) in people who are genetically sensitive to it. In men it shows as a receding hairline and thinning crown; in women as a widening parting and thinning on top, usually with the front hairline kept. It is slow and progressive.
• Telogen effluvium (shedding). A sudden increase in hair falling out all over the scalp, typically two to three months after a trigger: fever or serious illness, childbirth, surgery, crash dieting, a major stressor, or starting or stopping some medicines. It usually settles by itself within about six months once the trigger has passed. Low iron and thyroid problems can cause or prolong it.
• Alopecia areata. An autoimmune condition causing round, smooth bald patches, sometimes in the beard or eyebrows. It needs a dermatologist; newer prescription tablets (JAK inhibitors) are now approved for severe cases.
• Traction alopecia. Loss along the hairline from tight braids, ponytails, weaves or extensions. Early on it is reversible if the tension stops.
• Scarring (cicatricial) alopecias. Inflammatory conditions that destroy follicles permanently, often with itching, burning, redness or scaling around hairs. Early treatment matters because lost follicles do not come back.
• Other causes: fungal scalp infection (mostly in children), cancer treatment, thyroid disease, iron deficiency, polycystic ovary syndrome, and some medicines.

Everything below is about pattern hair loss unless stated. If your hair loss does not fit that pattern, the treatment is different, and a diagnosis comes first.

What works for pattern hair loss

Minoxidil (topical, non-prescription)

Minoxidil was first a blood-pressure tablet; the hair growth was a side effect. As a scalp solution or foam it prolongs the growing phase of the hair cycle and enlarges shrunken follicles. In a 48-week trial of 393 men, 5% minoxidil twice daily beat both 2% and placebo on hair counts and on how patients and investigators rated coverage, with 45% more regrowth than the 2% strength. Strong evidence1 study A parallel trial in 381 women found 5% superior to placebo on all main measures and 2% superior on hair counts, with more itching and unwanted facial hair at the higher strength. Strong evidence1 study These were large registration-era trials, and the benefit has held up in later independent meta-analyses.

What to expect:

• A shedding phase in the first 2–8 weeks is common and a sign that resting hairs are being pushed into a new growth cycle.
• Judge it at six to twelve months, not before. Slowing further loss is itself a success.
• It only works while you use it. Gains are typically lost within a few months of stopping.
• Side effects: itching and flaking (the solution contains propylene glycol; the foam usually does not), unwanted hair on the face or forehead, and rarely dizziness or a racing heart.

Low-dose oral minoxidil, a small daily tablet, has become a popular off-label prescription for people who cannot manage topical treatment. A review of 17 studies found it effective and generally well tolerated, and a randomised trial in 90 men found 5 mg daily was not superior to 5% topical minoxidil twice a day over 24 weeks. Moderate evidence2 studies Because it acts on blood vessels throughout the body, it can cause body-hair growth, fluid retention, a faster heart rate and dizziness, and it is not suitable for people with some heart conditions. It needs a prescriber, not an online shortcut.

Finasteride (prescription, men)

Finasteride blocks the enzyme that converts testosterone into DHT. In two one-year trials of 1,553 men aged 18–41, 1 mg daily increased hair counts in a one-inch circle of the crown by 107 hairs at one year and 138 at two years relative to placebo, while the placebo group kept losing hair. Strong evidence1 study The trials were run by the manufacturer, but independent meta-analyses agree that finasteride and minoxidil both work. Strong evidence1 study Combining finasteride with minoxidil is common, because they work in different ways.

Finasteride’s safety profile

In the original trials, sexual side effects — lower libido, erectile difficulty, reduced ejaculate — were reported by a few percent of men on finasteride, only slightly more than on placebo, and usually resolved on stopping. The harder questions have come since:

• Mood and suicidal thoughts. An analysis of the World Health Organization’s global adverse-event database found a disproportionate number of reports of suicidality and psychological side effects in men under 45 using finasteride for hair loss, though reporting may have been boosted by publicity. Emerging evidence1 study In 2025 the European Medicines Agency confirmed suicidal ideation as a possible side effect of finasteride tablets, of unknown frequency, and added a patient card to 1 mg packs, while concluding that the benefits still outweigh the risks.
• Persistent symptoms. Some men report sexual, cognitive or mood symptoms that continue after stopping, sometimes called post-finasteride syndrome. How often this happens, and why, is not established.
• PSA. Finasteride roughly halves PSA, the prostate blood test. Tell any doctor checking your PSA that you take it.

Topical finasteride aims to keep the drug in the scalp. In a 24-week European trial of 458 men, a finasteride spray increased hair counts more than placebo, by a similar amount to oral finasteride, with blood levels more than 100 times lower. Moderate evidence1 study In the US there is no approved topical finasteride; products sold through telehealth are compounded, and in 2025 the FDA warned about adverse-event reports with them, including sexual dysfunction, depression and suicidal thoughts. Lower blood levels are not the same as no risk.

Low-level laser and light devices

Laser combs, caps and helmets shine red light on the scalp. In four sham-controlled trials partly funded by the device maker (which also supplied the devices), men and women using a laser comb three times a week for 26 weeks gained about 18–26 hairs per square centimetre, against 2–9 with the sham. Moderate evidence1 study The meta-analysis above also found laser therapy beat placebo in men. Caveats: many trials are industry-funded, devices vary widely in power and wavelength, FDA “clearance” is a lower bar than drug approval, and long-term data are thin. It is a reasonable add-on or an option for people who cannot use drugs. Our red light therapy guide covers the wider evidence.

Other options

Platelet-rich plasma injections have mixed evidence and no standard protocol. Microneedling may help minoxidil work better in small trials. Hair transplantation works well for stable pattern loss when there is enough donor hair, though medication is usually still needed to protect the remaining hair.

What doesn’t work (or isn’t proven)

Biotin

Biotin is the default ingredient in hair gummies. A systematic review found only 18 reported cases where biotin helped hair or nails, and every one of them had an underlying condition, such as a genuine deficiency or a rare hair disorder. There is no good evidence it helps people who are not deficient, and true deficiency is rare. Moderate evidence1 study

Biotin can also cause harm indirectly. Many laboratory blood tests use biotin as part of their chemistry, and high-dose supplements interfere. When six healthy adults took 10 mg a day for a week, 9 of 23 such tests gave wrong results, some falsely high and some falsely low — including thyroid tests. Moderate evidence1 study The FDA has warned that biotin can cause falsely low troponin results — the blood test used to diagnose heart attacks — and has received a report of a patient on high-dose biotin who died after such a result.

Other supplements

Unless you are deficient, hair vitamins are unlikely to help. Iron deficiency is worth checking in anyone with shedding, particularly women with heavy periods (see our iron guide), but taking iron you do not need does not grow hair. Too much vitamin A or selenium can cause hair loss. If you have heard that creatine causes baldness, see our creatine and hair loss guide.

“Growth” and “anti-hair-loss” shampoos

A shampoo sits on the scalp for a minute or two before being rinsed away, which is a poor way to deliver an active ingredient to the hair follicle. Caffeine, biotin, peptide and “thickening” shampoos may make hair look fuller for a day by coating the shaft, but that is cosmetic. Rosemary oil gets attention because of one trial in 100 people that found similar hair counts to 2% minoxidil after six months; with no placebo group and the weaker minoxidil strength as the comparator, it cannot show rosemary works. Emerging evidence1 study Ketoconazole shampoo has a small, old study suggesting some benefit in pattern loss; it is a reasonable companion to proven treatment but not a replacement. Emerging evidence1 study

Shampoos that do have evidence: dandruff

Dandruff and seborrhoeic dermatitis — flaking, itching and redness driven partly by Malassezia yeast — do respond to medicated shampoos. In a 246-person randomised trial, both 2% ketoconazole and 2.5% selenium sulfide shampoos clearly beat placebo for flaking and itching; ketoconazole was better tolerated. Strong evidence1 study Zinc pyrithione, coal tar and salicylic acid shampoos are other options. Leave the lather on for three to five minutes and use two or three times a week, then less often to keep it under control. Look for the active ingredient and its percentage on the label, not the marketing.

When to see a dermatologist

Frequently Asked Questions

Does minoxidil work for women?

Yes. Both 2% and 5% beat placebo in a 381-woman trial. The 5% foam once daily is a common starting point; unwanted facial hair is more likely at the higher strength and usually settles after stopping.

What happens if I stop minoxidil or finasteride?

The hair gained or kept because of the treatment is typically lost over the following months, returning you to where the underlying pattern would have taken you. These are ongoing treatments, not cures.

Is finasteride safe?

Most men take it without problems, and it has decades of use. But sexual side effects occur in a small minority, mood changes and suicidal thoughts are now a recognised possible side effect in Europe, and some men report symptoms that persist after stopping. Discuss your history with a prescriber and weigh it honestly.

Do laser caps work?

Trials, mostly funded by manufacturers, show more hair growth than sham devices. The effect is probably smaller and less certain than minoxidil or finasteride, but the devices have few side effects.

Will a biotin supplement stop my hair falling out?

Only if you are genuinely deficient, which is rare. For most people it does nothing for hair and can distort important blood tests.

The Bottom Line

Start with a diagnosis. For pattern hair loss, topical minoxidil is the evidence-based first step for men and women, finasteride is the stronger prescription option for men with side effects worth understanding, and laser devices are a modest, industry-studied add-on. Skip biotin and “growth” shampoos; use medicated shampoos for dandruff, which is what they are proven for. Whatever you choose, give it six to twelve months and expect to continue it. See the personal care learning track for more.

Compare hair treatments and shampoos on the Formulate personal care shelf →