Compare biotin supplements on the micrograms of biotin in each daily dose, the %NRV and the cost per day. The NHS says 0.9mg (900 micrograms) or less a day from supplements is unlikely to cause harm, and products vary widely, so check the label before you buy.
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What is biotin?
Biotin is one of the B vitamins, sometimes called vitamin B7. The NHS says biotin is needed in very small amounts to help the body make fatty acids, and that it's found in a wide range of foods, but only at very low levels.
The NHS also says the bacteria that live naturally in your bowel can make biotin, so it's not clear whether you need any extra from your diet. It says you should be able to get all the biotin you need from a varied and balanced diet.
Does biotin help hair?
Biotin has an authorised claim that it "contributes to the maintenance of normal hair", and another that it "contributes to the maintenance of normal skin", but only for a product that is at least a source of biotin.
Maintaining normal hair is not the same as hair growth, and there is no authorised claim that biotin helps with hair loss or thinning. If you're worried about hair loss, speak to your GP or pharmacist. "Where evidence is limited or inconclusive, we should say so openly," says Andy Arshad, who runs SupplementHQ.
How much biotin should you take a day?
The NHS doesn't set a daily amount for biotin, but it says 0.9mg or less a day of biotin in supplements is unlikely to cause any harm. 0.9mg is the same as 900 micrograms.
Labels show biotin in micrograms (mcg or µg) and as %NRV (Nutrient Reference Value). The NRV for biotin is 50 micrograms, so a 10,000 microgram tablet shows as 20,000%.
| On the label | %NRV | How it compares with NHS guidance |
|---|---|---|
| 50 micrograms | 100% | The NRV, the reference amount used on labels |
| 450 micrograms | 900% | Half the amount the NHS says is unlikely to cause harm |
| 900 micrograms (0.9mg) | 1,800% | The amount the NHS says is unlikely to cause harm |
| 5,000 micrograms (5mg) | 10,000% | More than five times that amount |
| 10,000 micrograms (10mg) | 20,000% | More than 11 times that amount |
"Some supplements advertise 1,000% or more of the Nutrient Reference Value, making them appear more powerful. But a higher dose doesn't automatically mean better results, and in some cases, excessive intake can be harmful," says Andy. Our guide to reading a supplement label explains %NRV.
Can you take too much biotin?
The NHS says there's not enough evidence to know what the effects might be of taking high daily doses of biotin supplements, and advises not taking too much, as this might be harmful.
Biotin products vary widely in strength, and some contain more than 0.9mg a day, so check the amount per daily dose. It's easy to go over without realising, because biotin is also in many multivitamins and hair, skin and nails formulas. Add up the biotin across everything you take.
Can biotin affect blood test results?
Yes. A May 2023 safety letter issued to UK healthcare professionals in agreement with the MHRA says biotin may interfere with thyroid blood tests that use a biotin-based method, giving falsely high or falsely low results.
The letter advises that patients who are taking, or have recently taken, biotin should tell their doctor, and that the laboratory should be told before tests are ordered. It also notes that multivitamins and hair, skin and nails supplements may contain biotin. If you have a blood test coming up, tell your doctor about every supplement you take.
Biotin tablets or drops?
Choose the format you'll take consistently, then compare the micrograms of biotin per daily dose and the cost per day. This collection includes tablets and capsules, drops, and collagen powders with added biotin.
How to compare value (example figures, not real products): a £9 pot of 120 tablets with 500 micrograms each, one a day, costs about 7.5p a day. A £12 bottle of drops giving 60 daily doses of 500 micrograms costs 20p a day, over two and a half times as much for the same amount. "Two products that look almost identical on the shelf can offer different value," says Andy.
Biotin with collagen or on its own?
That depends on what you're looking for, but combining them doesn't add any authorised claim for collagen. Collagen has no authorised health claims, and the biotin claims apply only where a product is at least a source of biotin.
Combination products often cost more per day, so compare the biotin per dose and the collagen per serving separately. Browse collagen powder, hair, skin and nails formulas, or our collagen and beauty range.
Who should be careful with biotin supplements?
Anyone with a blood test coming up, anyone already taking a multivitamin or beauty supplement, and anyone who is pregnant, breastfeeding, has a medical condition or takes medication should speak to their GP or pharmacist first.
If you're unsure whether you need a supplement at all, our guide to what supplements you actually need is a good place to start. You can also compare multivitamins, which often contain biotin.
We sell the products on this page. That's our commercial interest, and it's why we show the evidence alongside them. This page is general information for adults, not personalised medical advice. Food supplements should not replace a varied, balanced diet.
Written by Andy Arshad, SupplementHQ. Last reviewed 11 October 2026.