Last update: March 2026 — Written by the ORVOVA team, proofread by our dermocosmetics advisor.
Type “hair loss” into any search engine, and biotin comes to the top of the recommendations. Hair supplements all contain them. Influencers praise it. Brands promote it as a star ingredient.
But what does science really say? Does biotin make hair grow, or is it one of the most profitable myths in the cosmetic industry?
This article sorts out clinical data and marketing. Without filter, without affiliation, without commercial agenda.
What exactly is biotin?
Biotin — also called vitamin B7 or vitamin H — is a water-soluble vitamin from group B. It plays a role as an enzymatic cofactor in several essential metabolic reactions.
Its main functions:
- Macronutrient metabolism: Biotin is necessary for the transformation of proteins, fats and carbohydrates into cellular energy
- Synthesis of keratin: it participates in the production of keratin, the main protein of hair, skin and nails
- Regulation of genetic expression: via histone biotinylation, it modulates the activity of certain genes
The recommended daily allowance (RDA) is 30 micrograms for adults. Biotin is present in many foods: eggs (cooked yolk), liver, nuts, sunflower seeds, sweet potatoes, spinach, cheese.
A crucial point that marketing systematically forgets to mention: biotin deficiency is extremely rare in the general population. Biotin is produced by intestinal bacteria, present in many foods, and the requirements are very low. Less than 1% of the population of developed countries presents a true deficiency.
What clinical studies say (and don’t say)
This is where the marketing narrative breaks down. Let's review what the scientific literature has actually shown.
Studies that support biotin
In 2012, a study published in Skin Appendage Disorders analyzed 18 case reports of biotin supplementation in patients with hair and nail problems. Result: all patients who showed improvement had a previously identified biotin deficiency.
The studies that show a positive effect of biotin on hair share one thing in common: the subjects were deficient. In a person deficient in biotin, the supplement restores normal keratin synthesis and the hair regains its quality. This is logical, expected, and not debatable.
Studies in non-deficient people
And that's where the problem lies. To date, no randomized, double-blind clinical study has demonstrated a benefit of biotin supplementation on hair growth or loss in non-deficient people.
A systematic review published in 2017 in Skin Appendage Disorders by Patel et al. analyzed all the available literature. 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 are not biotin deficient (which is very likely), taking extra biotin won't do anything for your hair.
Why do the add-ins seem to work anyway?
Three reasons explain the positive testimonials:
1. The placebo effect.When you take a “hair” supplement for 30 euros per month, you want it to work. Confirmation bias does the rest. We notice the regrowth (which would have happened anyway) and we ignore the hair which continues to fall out.
2. Multi-ingredient supplementsMost “biotin hair” supplements do not only contain biotin. They also contain zinc, iron, vitamin D, selenium, sulfur amino acids. If one of these nutrients corrects a real deficiency, the improvement is attributed to biotin even though it comes from another ingredient.
3. Time.Most hair loss (telogene effluvium) resolves within 6 to 12 months. When we start a supplement in month 3 of hair loss and the hair grows back in month 9, we attribute the regrowth to the supplement even though it would have happened anyway.
[IMAGE: Food supplement capsules on a white background, with a stylized question mark]
The (real) cases where biotin is justified
Biotin is not useless. It is useless when it is not necessary. Here are the situations where supplementation is medically justified.
1. Proven biotin deficiency
Symptoms: dry and brittle hair, dermatitis (skin rash around the eyes, nose and mouth), fragile nails, fatigue, paresthesias. A blood test confirms the diagnosis.
Causes of deficiency: excessive consumption of raw egg whites (avidin in raw egg white blocks the absorption of biotin), chronic alcoholism, certain antiepileptic drugs (valproate, carbamazepine), pregnancy, inflammatory intestinal diseases.
2. Biotinidase deficiency
It is a rare genetic disease (1/60,000 births) in which the body cannot recycle biotin. It is detected at birth in most countries. Affected people require lifelong supplementation.
3. Pregnancy and breastfeeding
Approximately one third of pregnant women develop a subclinical biotin deficiency. Needs are increasing and food intake is not always sufficient. In this case, a moderate supplement (30 to 50 mcg/day) is reasonable, ideally as part of prenatal monitoring.
The little-known risks of excessive supplementation
Since biotin is water soluble, the excess is assumed to be eliminated through urine. This is true for direct toxicity — there is no known toxic dose. But there is a serious problem that the manufacturers never mention.
Biotin distorts blood tests
In 2017, the US FDA issued an official warning: high doses of biotin (common in hair supplements, often at 5,000 or 10,000 mcg — or 150 to 300 times the RDA) interfere with laboratory tests based on streptavidin-biotin technology.
Concretely, excess biotin can:
- Distort troponin dosage (cardiac marker) → a heart attack may be missed
- Distorting the TSH dosage → thyroid dysfunction can be ignored or wrongly diagnosed
- Distort hormonal dosages (testosterone, estradiol, cortisol)
- Distort certain tumor markers
The FDA reports at least one death linked to a falsely low troponin dosage in a patient supplemented with biotin.
If you are taking biotin: stop taking the supplement at least 72 hours before any blood test. And inform your doctor.
[IMAGE: Blood collection tube and biotin tablets, illustrating the risk of interference with analyses]
Active ingredients that really work (when biotin is not enough)
If biotin is the tree that hides the forest, what are the active ingredients whose effectiveness is documented by serious studies?
Rosemary (essential oil or extract)
The study by Panahi et al. (2015, published in SKINmed) is the reference. 100 patients with androgenic alopecia received either rosemary essential oil or 2% minoxidil for 6 months. Result: comparable effectiveness on hair counting, with significantly less itching in the rosemary group.
The mechanism: rosemary contains carnosic acid and carnosol, two compounds that improve the microcirculation of the scalp 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 reside). It activates the division of these cells and prolongs the anagen phase.
The manufacturer's clinical study shows +17% hair in the growth phase and -17% hair in the shedding phase after 84 days of application.
Aminexil
Developed by L'Oreal, Aminexil is a derivative of minoxidil which prevents the hardening (fibrosis) of collagen around the hair root. When this collagen stiffens, it compresses the follicle and causes premature hair loss.
Several published clinical studies show a significant reduction in hair loss after 6 weeks of daily application.
The Anagain
Derived from organic peas (Pisum sativum), Anagain contains plant metabolites which stimulate the cells of the dermal papilla. The clinical study shows an improved anagen/telogen ratio of +78% in 12 weeks — meaning more follicles are in the growth phase.
These four active ingredients — Rosemary 3%, Redensyl 2%, Aminexil 2% and Anagain 2% — are combined in the ORVOVA Roll-On Hair Regrowth Serum. A single product, four complementary mechanisms of action, and a roll-on format which allows precise application without waste.
The verdict: should you take biotin for your hair?
Here is our position, based on the current state of 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 in 3 to 6 months.
If you don't have a deficiency: save your money. Extra biotin won't do anything for your hair. Instead, invest in a complete blood test (iron, ferritin, vitamin D, zinc, TSH) to identify possible real deficiencies, and in topical treatments whose effectiveness has been demonstrated.
If you don't know: have your blood biotin measured. It is a simple and inexpensive test. At least you will know.
The hair supplement market is worth several billion euros. It is in his best interest to make you believe that biotin is essential. The studies tell a different story. Listen to the science, not the packaging.
[IMAGE: Foods rich in biotin (eggs, nuts, sunflower seeds, spinach) arranged on a wooden board]
Alternatives to biotin: what dermatologists recommend
When a patient presents with hair loss, dermatologists do not prescribe biotin as first intention. Here's what they rate and recommend.
The target nutritional assessment
The four nutrients most frequently deficient in women who lose their hair:
- Ferritin (iron reserve): ferritin below 40 ng/mL is associated with hair loss, even if hemoglobin is normal. The therapeutic objective is 70 ng/mL minimum.
- Vitamin D: a level below 30 ng/mL is correlated with telogen effluvium and alopecia areata. In France, around 80% of the population is insufficient in vitamin D in winter.
- Zinc: essential for cell division of the follicle. A deficit, even moderate, slows down the hair cycle.
- TSH: hypothyroidism (even mild hypothyroidism) is a major cause of hair loss in women. It is often diagnosed late.
Topical treatment
Dermatologists favor treatments applied directly to the scalp. Logic: the active ingredients arrive directly at the follicle, without going through digestion.
Minoxidil remains the pharmaceutical reference treatment. But active ingredients of natural or biotechnological origin — rosemary, Redensyl, Aminexil, Anagain — offer effective alternatives without the side effects (hypertrichosis, irritation, rebound effect after stopping).
Scalp massage
Underestimated and 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, with no side effects, and can be combined with all other treatments.
FAQ — Biotin and hair
Does biotin really make hair grow faster?
In a person deficient in biotin, yes. In a person with normal biotin status (the vast majority of the population), studies show no measurable effect on growth speed or reduction in shedding.
How much biotin to take for hair?
The recommended daily intake is 30 micrograms. Hair supplements often contain 5,000 to 10,000 mcg (150 to 300 times the RDA). If you do not have a deficiency, even a high dose will not produce 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 have to take biotin to see an effect?
In case of deficiency treated by supplementation, the first effects are visible after 3 to 6 months (the time for new hair to grow). If you don't see any effects 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. An excess of biotin blocks the absorption of B5, and a deficiency of B5 promotes acne. The association is not 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 needs.
