Question & Context

Hair loss – what demonstrably helps?

In brief

That depends on the cause. In common hereditary hair loss, topical minoxidil and, in men, finasteride are the best-supported remedies; they slow the loss and, in studies, make hair grow back. Red light caps and PRP injections show a benefit in studies, though with weaker data. Increased shedding a few months after fever, childbirth, major weight loss or severe stress usually resolves on its own. Hair vitamins only help with a real deficiency, and too much selenium can even trigger hair loss.

What matters first

Stay calm and count

Losing 50 to 100 hairs a day is normal. If you find clearly more in your brush or in the drain, you should watch whether the hair is thinning evenly, receding in certain areas or whether round bald patches are appearing. The pattern is the most important clue to the cause.

Think back over the last few months

Increased hair loss often begins a few months after a stressful event, for example after a high fever, an operation, childbirth, major weight loss, stopping the pill or a period of severe stress. After childbirth it usually shows after around two months and reaches its peak after about four months. Within six to nine months, the hair usually becomes as full as before.

Act early if it is hereditary

In hereditary hair loss, the hair roots become smaller over time, and the process does not stop on its own: in the large finasteride trials, the men on placebo steadily continued to lose hair. If you want to slow the loss, you therefore do not have to wait for years.

No megadoses of hair vitamins

Many hair products contain large amounts of biotin or selenium. According to the US Food and Drug Administration, biotin can severely distort laboratory tests, including the heart attack marker troponin. And too much selenium itself causes hair loss; the European food safety authority derived its upper limit for precisely this reason.

When you should have this checked by a doctor

Have hair loss checked by a dermatologist if it starts suddenly and severely, if round bald patches appear, if the scalp itches, flakes, hurts or looks scarred, or if it does not ease after six to nine months. If tiredness, sensitivity to cold, weight changes, menstrual cycle disorders or increased body hair come on top, the thyroid, iron status and hormones should also be looked at. If you are taking new medications, mention this to your doctor. If you take biotin, mention it before every blood test, because it can distort laboratory values.

What really works

For hereditary hair loss there are two well-studied active substances. Minoxidil is applied to the scalp; a meta-analysis found it more effective than placebo in men and women. In the Cochrane review on female hair loss, covering 47 studies, almost twice as many women on minoxidil reported clear regrowth as on placebo, and the researchers counted on average a good 13 more hairs per square centimeter.

Finasteride is a prescription-only tablet for men. In the approval trials with 1,553 men, 107 more hairs were counted after one year than on placebo, and 138 after two years, while on placebo the loss continued. Over five years, the risk of further visible hair loss fell by 93 percent. Sexual side effects occurred in 1.9 to 6.7 percent in the trials, and in 0.9 to 3.9 percent on placebo. Since September 2025, a Dear Healthcare Professional Letter (Rote-Hand-Brief) has warned of suicidal thoughts: in case of low mood, the medication should be stopped and medical advice sought.

What can complement it

Red light via caps or combs is the third option with usable data. An overview of 15 meta-analyses found moderate certainty of evidence for hair density in hereditary hair loss, one of the best ratings for red light of all. However, the largest blinded trial of an LED cap to date missed its primary goal, and the devices differ greatly.

PRP, that is, processed autologous blood, is injected into the scalp. A meta-analysis of 43 randomized trials with 1,877 participants showed better hair density and less hair loss; the authors rate the evidence as moderate. For food supplements, the rule is: they help if there is a deficiency, and otherwise hardly at all.

What the database says

Sorted by strength of evidence. The BK-Score rates the state of knowledge, not the substance.

Finasteride Evidence 9/10 · Well supported, heavily overhypedThe best-studied remedy for hereditary hair loss in men: in the approval trials, 107 more hairs grew after one year than on placebo. Since 2025 there has been a Dear Healthcare Professional Letter (Rote-Hand-Brief) on suicidal thoughts; prescription-only and to be supervised by a doctor.
Iron Evidence 9/10 · Well supported, heavily overhypedIron deficiency is common, especially in menstruating women, and is one of the things you can have checked with diffuse hair loss. Taking iron makes sense when a deficiency has been proven.
Selenium Evidence 9/10 · Well supported, heavily overhypedSelenium is needed for normal hair, but too much of it triggers hair loss. The European upper limit is derived from precisely this effect, which is why it is worth looking at the total amount from supplements and Brazil nuts.
Red light / photobiomodulation (PBM) Evidence 5/10 · Thin human evidenceFor hair density in hereditary hair loss, red light is the best-supported area of use for photobiomodulation, with moderate certainty of evidence. A large blinded trial with an LED cap, however, missed its primary goal.
PRP (autologous blood therapy) Evidence 5/10 · Studied – no benefit shownIn a meta-analysis of 43 randomized trials, autologous blood injections improved hair density and hair loss, but not hair thickness. The authors rate the evidence as moderate.
Collagen peptides Evidence 5/10 · Thin human evidenceOften promoted for skin, hair and nails. The existing studies are small, mostly funded by manufacturers and concern mainly the skin, not hair loss.
Spermidine Evidence 5/10 · Thin human evidenceFor hair, there is so far only one indication from a manufacturer-funded study with a combination product. That is not enough for a recommendation.

Frequently asked questions

How many hairs a day is it normal to lose?

Between 50 and 100 hairs a day are considered normal. It becomes noticeable when clearly more fall out over weeks or visible gaps form.

Does hair grow back after stress or childbirth?

In most cases, yes. The increased shedding usually begins a few months after the triggering event and improves within six to nine months. If the strain continues, it can take longer.

Do biotin and hair vitamins help?

With a real deficiency, nutrients can help; without a deficiency, a benefit is not proven. High-dose biotin can distort laboratory tests, including important heart values. Too much selenium can even trigger hair loss.

Is minoxidil also suitable for women?

Yes, topical minoxidil is the best-studied remedy for female hair loss. In the Cochrane review, almost twice as many women reported clear regrowth as on placebo. Get advice from a doctor or pharmacist before you start, especially during pregnancy and breastfeeding.

How dangerous is finasteride?

In studies, sexual side effects occurred in a small proportion of men, somewhat more often than on placebo, and mostly went away after stopping. Since 2025 there has been an official warning about suicidal thoughts, whose frequency is not known. In case of low mood, you should stop the tablets and seek medical advice.

When should I see a dermatologist?

With sudden heavy shedding, round bald patches, an inflamed or scarred scalp, or if the shedding does not ease after a few months. It is also worth getting checked if other complaints such as tiredness or menstrual cycle disorders come on top. Treatments work best when started early.