Last updated: March 2026 — Written by the ORVOVA team, reviewed by our dermocosmetics adviser.
Type "hair falling out" into any search engine and biotin tops the list of recommendations. Every hair supplement contains it. Influencers rave about it. Brands push it as their star ingredient.
But what does the science actually say? Does biotin make hair grow, or is it one of the most profitable myths in the beauty industry?
This article separates the clinical data from the marketing. No filter, no affiliation, no commercial agenda.
Contents
- What exactly is biotin?
- What the clinical studies do (and don't) say
- The (genuine) cases where biotin is justified
- The little-known risks of excessive supplementation
- The actives that genuinely work (when biotin isn't enough)
- The verdict: should you take biotin for your hair?
- Alternatives to biotin: what dermatologists recommend
- FAQ — Biotin and hair
What exactly is biotin?
Biotin — also known as vitamin B7 or vitamin H — is a water-soluble B-group vitamin. It acts as an enzyme cofactor in several essential metabolic reactions.
Its main functions:
- Macronutrient metabolism: biotin is needed to turn proteins, fats and carbohydrates into cellular energy
- Keratin synthesis: it plays a part in producing keratin, the main protein in hair, skin and nails
- Gene expression regulation: through histone biotinylation, it modulates the activity of certain genes
The recommended daily intake (RDI) is 30 micrograms for adults. Biotin is found in plenty of foods: eggs (cooked yolk), liver, nuts, sunflower seeds, sweet potatoes, spinach, cheese.
One crucial point the marketing consistently forgets to mention: biotin deficiency is extremely rare in the general population. Biotin is produced by gut bacteria, present in many foods, and our requirements are very low. Fewer than 1% of people in developed countries have a genuine deficiency.
What the clinical studies do (and don't) say
This is where the marketing narrative falls apart. Let's review what the scientific literature has actually demonstrated.
The studies that support biotin
In 2012, a study published in Skin Appendage Disorders analysed 18 reported cases of biotin supplementation in patients with hair and nail problems. The result: every patient who improved had a previously identified biotin deficiency.
The studies showing a positive effect of biotin on hair all share one thing in common: the subjects were deficient. In someone who is biotin-deficient, supplementation restores normal keratin synthesis and hair quality recovers. That's logical, expected and not up for debate.
The studies in non-deficient people
And this is where it breaks down. To date, no randomised double-blind clinical trial has demonstrated any benefit of biotin supplementation on hair growth or hair loss in people who are not deficient.
A systematic review published in 2017 in Skin Appendage Disorders by Patel et al. analysed the entire available literature. The authors' conclusion: "Evidence of a benefit from biotin supplementation is limited to cases of biotin deficiency. There is insufficient data to recommend supplementation in individuals with normal biotin levels."
In other words: if you're not biotin-deficient (which is highly likely), taking extra biotin will do nothing for your hair.
So why do supplements seem to work anyway?
Three reasons explain the positive testimonials:
1. The placebo effect. When you're spending 30 euros a month on a "hair" supplement, you want it to work. Confirmation bias does the rest. You notice the regrowth (which would have happened anyway) and overlook the hairs that keep falling.
2. Multi-ingredient supplements. Most "biotin hair" supplements don't contain only biotin. They also contain zinc, iron, vitamin D, selenium and sulphur amino acids. If one of those nutrients corrects a genuine deficiency, the improvement gets credited to biotin when it actually came from another ingredient.
3. Time. Most hair loss (telogen effluvium) resolves on its own within 6 to 12 months. If you start a supplement in month 3 of the shedding and your hair grows back in month 9, you credit the supplement with regrowth that would have happened regardless.
[IMAGE: Supplement capsules on a white background with a stylised question mark]
Also read our article on hair supplements.
The (genuine) cases where biotin is justified
Biotin isn't useless. It's useless when it isn't needed. Here are the situations where supplementation is medically justified.
1. A confirmed biotin deficiency
Symptoms: dry, brittle hair, dermatitis (a rash around the eyes, nose and mouth), fragile nails, fatigue, paraesthesia. A blood test confirms the diagnosis.
Causes of deficiency: eating large amounts of raw egg white (avidin in raw white blocks biotin absorption), chronic alcoholism, certain antiepileptic medications (valproate, carbamazepine), pregnancy, inflammatory bowel disease.
2. Biotinidase deficiency
This is a rare genetic condition (1 in 60,000 births) in which the body cannot recycle biotin. It's screened for at birth in most countries. Those affected need lifelong supplementation.
3. Pregnancy and breastfeeding
Around a third of pregnant women develop a subclinical biotin deficiency. Requirements rise and dietary intake isn't always enough. In that case, moderate supplementation (30 to 50 mcg/day) is reasonable, ideally as part of antenatal care.
The little-known risks of excessive supplementation
Since biotin is water-soluble, any excess is assumed to be flushed out in urine. That's true for direct toxicity — there is no known toxic dose. But there is a serious problem manufacturers never mention.
Biotin skews blood test results
In 2017, the US FDA issued an official warning: high doses of biotin (common in hair supplements, often 5,000 or 10,000 mcg — 150 to 300 times the RDI) interfere with laboratory tests based on streptavidin-biotin technology.
In practical terms, excess biotin can:
- Skew troponin results (a cardiac marker) → a heart attack can be missed
- Skew TSH results → thyroid dysfunction can be overlooked or wrongly diagnosed
- Skew hormone tests (testosterone, oestradiol, cortisol)
- Skew certain tumour markers
The FDA has reported at least one death linked to a falsely low troponin reading in a patient taking biotin supplements.
If you take biotin: stop supplementing at least 72 hours before any blood test. And tell your doctor.
[IMAGE: Blood test tube and biotin tablets, illustrating the risk of interference with lab results]
The actives that genuinely work (when biotin isn't enough)
If biotin is the tree that hides the forest, which actives actually have their effectiveness backed by serious research?
Rosemary (essential oil or extract)
The study by Panahi et al. (2015, published in SKINmed) is the benchmark. 100 patients with androgenetic alopecia received either rosemary essential oil or 2% minoxidil for 6 months. The result: comparable effectiveness on hair count, with significantly less itching in the rosemary group.
The mechanism: rosemary contains carnosic acid and carnosol, two compounds that improve scalp microcirculation and have anti-inflammatory properties.
Redensyl
Patented by the Swiss laboratory Induchem, Redensyl targets the stem cells of the bulge (the area of the follicle where hair stem cells live). It triggers these cells to divide and extends the anagen phase.
The manufacturer's clinical study shows +17% hairs in the growth phase and -17% hairs in the shedding phase after 84 days of application.
Aminexil
Developed by L'Oreal, Aminexil is a minoxidil derivative that prevents the hardening (fibrosis) of the collagen around the hair root. When that collagen stiffens, it compresses the follicle and causes the hair to shed prematurely.
Several published clinical studies show a significant reduction in hair loss after 6 weeks of daily application.
Anagain
Derived from organic pea (Pisum sativum), Anagain contains plant metabolites that stimulate the cells of the dermal papilla. The clinical study shows an anagen/telogen ratio improved by +78% in 12 weeks — meaning more follicles are in the growth phase.
These four actives — Rosemary 3%, Redensyl 2%, Aminexil 2% and Anagain 2% — are combined in the ORVOVA Roll-On Hair Growth Serum. One product, four complementary mechanisms of action, and a Roll-On format for precise application with nothing wasted.
Also worth reading: our complete guide to natural keratin for hair.
The verdict: should you take biotin for your hair?
Here's our position, based on the current state of the science:
If you have a diagnosed biotin deficiency: yes, supplement. The therapeutic dose is 2,500 to 5,000 mcg/day, under medical supervision. Hair improvement will be visible within 3 to 6 months.
If you're not deficient: save your money. Extra biotin will do nothing for your hair. Invest instead in a full blood panel (iron, ferritin, vitamin D, zinc, TSH) to identify any real deficiencies, and in topical treatments with demonstrated effectiveness.
If you don't know: get your blood biotin measured. It's a simple, inexpensive test. At least then you'll know.
The hair supplement market is worth several billion euros. It has every interest in making you believe biotin is essential. The studies tell a different story. Listen to the science, not the packaging.
[IMAGE: Biotin-rich foods (eggs, nuts, sunflower seeds, spinach) arranged on a wooden board]
Alternatives to biotin: what dermatologists recommend
When a patient comes in with hair loss, dermatologists don't prescribe biotin as a first-line treatment. Here's what they assess and recommend instead.
Targeted nutritional testing
The four nutrients most often deficient in women losing their hair:
- Ferritin (iron stores): ferritin below 40 ng/mL is associated with hair loss, even when haemoglobin is normal. The therapeutic target is at least 70 ng/mL.
- Vitamin D: a level below 30 ng/mL correlates with telogen effluvium and alopecia areata. In France, around 80% of the population is vitamin D insufficient in winter.
- Zinc: essential for cell division in the follicle. Even a moderate deficit slows the hair cycle.
- TSH: hypothyroidism (even subclinical) is a major cause of hair loss in women. It is often diagnosed late.
Topical treatment
Dermatologists favour treatments applied directly to the scalp. It makes sense: the actives reach the follicle directly, without passing through digestion.
Minoxidil remains the benchmark pharmaceutical treatment. But natural and biotech actives — rosemary, Redensyl, Aminexil, Anagain — offer effective alternatives without the side effects (hypertrichosis, irritation, rebound shedding on stopping).
Scalp massage
Underrated, yet effective. The study by Koyama et al. (2016) shows a significant increase in hair thickness after 24 weeks of daily 4-minute massage. Free, side-effect free, and can be combined with every other treatment.
You might also like: complete anti-hair-loss routine.
FAQ — Biotin and hair
Does biotin really make hair grow faster?
In someone who is biotin-deficient, yes. In someone with normal biotin status (the vast majority of the population), studies show no measurable effect on growth speed or on reducing hair loss.
What dose of biotin should you take for your hair?
The recommended daily intake is 30 micrograms. Hair supplements often contain 5,000 to 10,000 mcg (150 to 300 times the RDI). If you're not deficient, even a high dose will produce no hair benefit. If you have a confirmed deficiency, 2,500 to 5,000 mcg/day under medical supervision is the usual therapeutic dose.
How long do you need to take biotin to see an effect?
Where a deficiency is being treated with supplementation, the first effects are visible after 3 to 6 months (the time it takes for new hair to grow). If you see no effect after 6 months, biotin is probably not your problem.
Can biotin cause acne?
Cases of acne have been reported with high doses of biotin (5,000+ mcg). The suspected mechanism: biotin and vitamin B5 (pantothenic acid) share the same intestinal transporter. Excess biotin blocks B5 absorption, and a B5 deficit encourages acne. The link isn't proven by clinical trials, but it is biologically plausible.
Which foods contain the most biotin?
Cooked egg yolk (25 mcg per egg), beef liver (31 mcg/100g), sunflower seeds (10 mcg/30g), almonds (5 mcg/30g), sweet potatoes (5 mcg/100g) and salmon (5 mcg/100g). Two eggs a day cover almost all of your requirements.
