Biotin
Browse biotin supplements, vitamin B7, in tablets, capsules, drops and B-complex formulas. We explain which strength makes sense, how the forms differ and why the highest number on the label is not the goal.Read more →
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What biotin does and how the forms differ
Biotin is vitamin B7, a water-soluble B vitamin. In several European countries the same nutrient is numbered B8, so both names describe one molecule. Your body uses biotin as a helper for enzymes that break down fat, carbohydrate and protein from food. Because it dissolves in water, you store very little of it. A steady daily habit therefore matters more than one large dose.
Most people in the UK get enough biotin from a mixed diet, so this is rarely a page about filling a gap. People usually buy it for a specific reason: extra support for hair and skin, or because they already take a Vitamin B complex and want to know what the B7 in it does.
The European food safety authority (EFSA) has approved a short, clear list of claims for biotin. Biotin contributes to:
- the maintenance of normal hair and normal skin
- normal energy-yielding metabolism and normal macronutrient metabolism
- the normal functioning of the nervous system and normal psychological function
- the maintenance of normal mucous membranes
Nails are not on that list. Biotin has no approved nail claim in the EU, while zinc and selenium each contribute to the maintenance of normal nails. That is useful to know if brittle nails are your main reason for buying, and it explains why so many hair and nail formulas combine biotin with those two minerals instead of selling biotin on its own.
Biotin comes mainly from eggs, liver, nuts, seeds and pulses, always in small amounts. People eating little variety, or following a long-term restricted diet, are the ones most likely to run low.
Why the strength on the label is not the whole story
Adults have an adequate intake of 40 micrograms a day, roughly what a couple of cooked eggs deliver. Most tablets on the UK market contain 5,000 or 10,000 micrograms. The NHS states that 0.9 mg a day or less from supplements, which is 900 micrograms, is unlikely to cause harm, so high-strength tablets sit above that figure. They are widely used and well tolerated, and they suit people who want to trial a high dose deliberately. If you would rather stay close to official guidance, a lower strength does the same nutritional job.
How we choose the biotin we stock
We look at three things: the form, the dose and the combination. We want d-biotin, the form the body actually uses, with the dose stated per tablet or capsule rather than per double serving. We keep low-strength options alongside the popular high-strength tablets, because not everyone wants hundreds of times the reference intake. Combinations only earn a place when the extra ingredients carry their own approved role, such as zinc for nails. We buy directly from the brands, our compliance team checks every label, and we test products ourselves next to independent lab spot-checks. You can read how we select brands and products.
Expect patience rather than speed. Hair and nails grow slowly, so give any biotin routine three to six months of daily use before you judge it. Biotin needs no particular time of day and no food, which makes it easy to keep up. Some people run it next to collagen powders and drinks for the same goal. Two practical points: high doses can trigger spots in acne-prone skin, and biotin can skew laboratory blood tests, so tell your GP that you take it.
Frequently asked questions
What is biotin, and is it the same as vitamin B7 and vitamin B8?
Yes, all three names refer to the same water-soluble B vitamin. UK labels and the NHS use biotin or vitamin B7. In parts of continental Europe the same nutrient is numbered B8, which can be confusing when you compare products across borders. Chemically it is d-biotin, the form used in supplements and the form your body can use directly. There is no separate nutrient hiding behind the second number.
What does biotin do in the body?
Biotin works as a helper for enzymes that break down fat, carbohydrate and protein from your food. From that role come its approved claims: biotin contributes to normal energy-yielding metabolism, normal macronutrient metabolism, the maintenance of normal hair, normal skin and normal mucous membranes, and the normal functioning of the nervous system and normal psychological function. It does not act as a stimulant, so it will not feel like a shot of energy.
How much biotin do I need each day?
There is no UK recommended daily allowance for biotin, because deficiency is rare. EFSA instead sets an adequate intake, the amount observed to be enough in European diets.
| Group | Adequate intake (µg/day) |
|---|---|
| Children 1 to 3 years | 20 |
| Children 4 to 10 years | 25 |
| 10 to 17 years | 35 |
| Adults 18+ | 40 |
| Pregnancy | 40 |
| Breastfeeding | 45 |
The NHS adds that 0.9 mg or less a day from supplements is unlikely to cause harm.
Source: EFSA, NHSWhich form of biotin should I choose?
Choose on dose precision and on whether you like swallowing tablets. The nutrient itself is the same d-biotin in every form.
| Form | What it gives you | Suits |
|---|---|---|
| Tablet | Fixed dose, usually high strength | Simple daily routine |
| Capsule | Fixed dose, few fillers | Sensitive stomachs |
| Gummy | Lower dose, added sugar | People who dislike tablets |
| Liquid drops | Flexible dosing | Children, swallowing trouble |
| B-complex | Biotin plus other B vitamins | Broader B intake |
If you want to judge whether a set amount changes anything, a fixed-dose tablet or capsule makes that easier to track.
When should I take biotin and how long before I notice anything?
Any time of day works. Biotin is water-soluble and does not depend on a fatty meal, so consistency beats timing. Many people take it with breakfast simply because they remember it then. For hair and nails, allow three to six months of daily use. Nails take around six months to grow out fully and hair grows in cycles, so earlier judgements usually just measure growth that has not reached the surface yet.
Can I take biotin together with collagen, zinc or a multivitamin?
Yes. Biotin has no known interactions with collagen, minerals or multivitamins, and many hair and skin products already combine them. Check the totals rather than the number of pots: a multivitamin, a beauty formula and a standalone tablet can stack up to far more biotin than you intended. If nails are your focus, zinc supplements are worth a look, since zinc carries the approved nail claim that biotin does not.
Can high-dose biotin cause spots or other side effects?
Biotin is generally well tolerated and excess leaves the body in urine. Some people with acne-prone skin do report breakouts on very high doses, and mild digestive upset happens occasionally. If you notice either, dropping to a lower strength usually settles it, and a lower strength still covers your nutritional needs comfortably. Since evidence on long-term high daily doses is limited, the NHS advises keeping supplemental biotin at 0.9 mg a day or less.
Does biotin interfere with blood tests?
It can, and this is the one practical rule worth remembering. Many laboratory assays use a biotin and streptavidin binding step. High biotin levels in your blood can push those results falsely high or falsely low, including thyroid hormone, other hormone panels, vitamin D and the cardiac marker troponin. The sample is fine, the reading is not. Tell your GP or nurse that you take biotin and follow their advice on pausing it before a test.
