Biotin and hair supplements: what the evidence says

Walk down any pharmacy aisle and you will find biotin in hair, skin and nail formulas, gummies and high-strength capsules. It is the vitamin most closely tied to hair in people's minds. The evidence is much less impressive than the packaging, and there is one real risk that most labels don't mention.

What biotin is

Biotin is a B vitamin found in many foods. The NIH Office of Dietary Supplements says it helps turn the carbohydrates, fats and proteins in food into energy. ¹ Good food sources include meat, fish, eggs, organ meats such as liver, and some vegetables, such as sweet potatoes, spinach and broccoli. ¹

The ODS says most people get enough biotin from the foods they eat. ¹

Deficiency is rare

The link between biotin and hair is real but narrow. The ODS says biotin deficiency can cause thinning hair and loss of body hair, along with rashes, brittle nails and other problems. ¹ It also says biotin deficiency is very rare in the United States. ¹ Certain groups are more likely to have trouble getting enough, such as people with a rare genetic disorder called biotinidase deficiency. ¹

So biotin fixes hair loss caused by biotin deficiency. For almost everyone else, that is not what is causing their hair loss.

What the evidence says for everyone else

• The ODS says biotin supplements are often promoted to improve hair, skin and nails, but there is little scientific evidence to support these claims. ¹
• The American Academy of Dermatology says that in studies of supplements such as biotin and folic acid, the findings have been mixed, and in most studies the supplements had no effect on hair growth and thickness. ²
• DermNet notes a systematic review of 30 studies suggesting that nutritional supplements are something to discuss between patient and doctor. ⁴ It is a conversation, not a default.

The AAD adds a broader caution. Hair supplements are not regulated for safety and effectiveness before they are sold; that responsibility lies with the manufacturer. ⁵

The real risk: false lab results

This is the part most people don't know. The FDA says biotin, often found in dietary supplements, can significantly interfere with certain lab tests and cause incorrect results that may go undetected. ³ It has received reports of biotin causing falsely low results on troponin tests, which are used to help diagnose heart attacks. ³

The ODS says supplements containing biotin above recommended amounts may cause false results in some lab tests, including those that measure hormones such as thyroid hormone. ¹ Its health professional fact sheet describes falsely low readings of a thyroid hormone in one study, which could lead to a wrong diagnosis. ⁶

That matters especially for people with hair loss, because thyroid tests are a routine part of the workup. ⁴ If you take biotin, tell your doctor before any blood test, and ask whether to stop it first.

Can other supplements make hair loss worse?

Yes. The American Academy of Dermatology says getting too much of certain nutrients, including selenium, vitamin A and vitamin E, has been linked to hair loss. ⁵ It warns that supplements taken for hair can do more harm than good. ⁵ Hair, skin and nail formulas often combine several of these. Read the label, and count what you get from multivitamins too.

Reading a hair supplement label

A few minutes with the label tells you a lot.

• Look for the amount of each ingredient, not just the list. Many formulas contain several vitamins and minerals at once. ¹
• Add up overlaps. If you also take a multivitamin or a B-complex, you may be getting biotin, selenium or vitamin A from more than one product. ^{1 5}
• Treat promises with suspicion. Claims of fast regrowth or "clinically proven" results are the kind the FDA lists as warning signs of health fraud. ⁷
• Check with a pharmacist if you take prescription medicines, since some supplements can interact with them. ²

What to do instead

1. Find the cause of the hair loss first. The AAD says the key to results is knowing the cause. ⁸
2. Test before you supplement. The AAD suggests a blood test to find out whether you are short of a nutrient before taking anything for hair. ⁵
3. Treat a real deficiency properly. Low iron, for example, is a recognized cause of shedding and needs a doctor's guidance. ^{9 10}
4. Eat a varied diet. Most people get enough biotin from food. ¹

Our guide to diet and hair loss covers iron, protein and crash diets. Our guide to spotting hair loss scams covers marketing claims more broadly.

General information, not medical advice. This article was drafted with AI assistance and checked against the sources listed above. Nobody at Balds is a doctor. If something here is wrong or out of date, tell us.