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Limited evidenceVitaminsSkin & hair

Biotin

Also called: Vitamin B7, vitamin H

A B vitamin popular for hair and nails. It clearly helps people who are deficient, but evidence in healthy people is thin.

Typical amount
30–100 mcg covers needs; hair products often 5,000–10,000 mcg
Best time
Morning · Timing guide
Food
With food
Typical course
12 weeks, then review
Upper limit
No set upper limit; high doses disturb lab tests
Is it right for me?

Where to buy

3 products
Also inside 6 other products (combinations and multivitamins)

What is biotin?

Biotin helps the body turn food into energy and is needed for healthy hair, skin and nails. True deficiency is uncommon, but it can cause hair thinning and brittle nails. Many hair supplements contain very high doses (5,000–10,000 mcg), which can interfere with blood tests.

Forms. Tablets, capsules, gummies and oral strips, usually 1,000–10,000 mcg. Often combined in hair-skin-nail blends.

What it may help with

Evidence grade

Strong: several good human trials. Moderate: some trials, mixed results. Limited: small or early studies. Traditional: long use, little trial evidence.

Safety and interactions

Side effects
Well tolerated. High doses can make thyroid, hormone and heart (troponin) blood tests read falsely high or low.
Who should be careful
Interferes with thyroid, troponin and hormone tests
Spacing
Stop 2–3 days before any blood test
Medicines
Ask your doctor first if you take pregnancy or breastfeeding.
Stop and call a doctor if
Rash

Food sources

Eggs (cooked), nuts, seeds, sweet potato, mushrooms and legumes.

Common questions

Do I need to stop biotin before a blood test?

Yes. Stop it 2–3 days before any blood test, or as your lab advises, and tell the lab you take it.

Will biotin regrow my hair?

Only if hair loss is from low biotin. Iron, vitamin D, thyroid and protein are more common causes; a blood test helps.

Is 10,000 mcg too much?

It's far above needs. It isn't toxic, but it's more likely to disturb lab tests.

Sources

For information only, not medical advice. Prices and links are checked by hand and can change; we may earn a small commission on some links. This plan is based on your answers and is not a medical diagnosis. It does not replace advice from your doctor. If you take medicines or have a health condition, check with your doctor before starting any supplement.