Biotin for hair: the evidence, and the FDA's lab-test warning
There is little good evidence that biotin helps hair in healthy people. A 2017 review found 18 reported cases of biotin helping hair or nails, and in every one the patient had an underlying condition. [1] The FDA also says biotin, often found in dietary supplements, can significantly interfere with certain lab tests and cause incorrect results that may go undetected, so if you take it, tell your doctor and the lab. [2]
Does biotin help hair growth?
The honest answer is: not in healthy people, as far as the evidence shows. A 2017 review in Skin Appendage Disorders searched PubMed for case reports and randomized trials on biotin and hair or nails, and its results list 18 reported cases of biotin use for hair and nail changes. [1] In all 18, the patient had an underlying pathology for poor hair or nail growth, and all showed clinical improvement after receiving biotin. [1]
The authors drew a narrow conclusion. Biotin supplementation may be of benefit in acquired and inherited causes of biotin deficiency and in conditions such as brittle nail syndrome or uncombable hair, but they proposed that these cases are uncommon and that there is a lack of sufficient evidence for supplementation in healthy individuals. [1] The review opens by noting that biotin is commercially popular for hair and nail growth despite limited research in healthy people. [1]
The National Institutes of Health reaches the same place. Its Office of Dietary Supplements says supplements containing biotin are often promoted for hair, skin and nails, but there is little scientific evidence to support these claims. [3] It adds that doctors have reported high doses improving a rare hair disorder in children and a skin rash in infants in a few cases, and that more research is needed before biotin supplements can be recommended for such conditions. [3]
Can you be low in biotin?
Rarely. The Office of Dietary Supplements says biotin deficiency is very rare in the United States and that most people get enough from the foods they eat. [3] Foods that contain it include meat, fish, eggs and organ meats, seeds and nuts, and certain vegetables such as sweet potatoes, spinach and broccoli. [3] The groups it names as more likely to have trouble getting enough include people with a rare genetic disorder called biotinidase deficiency and people with alcohol dependence. [3]
Here is the part that makes biotin look like a hair vitamin: the same fact sheet lists thinning hair and loss of body hair among the effects of biotin deficiency. [3] That is a list of what a deficiency can cause, and the same page says deficiency is very rare. [3] Hair thinning is common in midlife for many other reasons; our article on what causes hair loss in women covers them.
Why does the FDA warn about biotin and lab tests?
Because biotin can change the result. The FDA says health care providers, lab personnel and lab test developers should be aware that biotin, often found in dietary supplements, can significantly interfere with certain lab tests and cause incorrect test results which may go undetected. [2] The agency says it continues to receive adverse event reports indicating that biotin interference caused falsely low troponin results. [2] Some test developers have since reduced the interference in their assays, but the FDA says others have not. [2]
The Office of Dietary Supplements puts it in consumer terms: supplements that contain biotin above recommended amounts may cause false results in some lab tests, including those that measure certain hormones, such as thyroid hormone. [3] The same page says biotin has not been shown to cause any harm in itself. [3] The risk is a wrong number on a lab report, which can lead to a wrong conclusion. We could not open the FDA's full safety communication on this topic, so we cite only the FDA page that we could read. [2]
What to tell your doctor and the lab
That you take biotin, and in what form: it is found in some multivitamin and mineral supplements, in B-complex supplements, and in supplements containing only biotin. [3] The Office of Dietary Supplements advises telling your doctor, pharmacist and other health care providers about any dietary supplements you take, because they can tell you whether a supplement might interact with your laboratory tests. [3] Ask your clinician, not a label, whether anything should change before a blood draw. We give no dose advice here.
Should you see a dermatologist before buying a hair supplement?
If the thinning is real, yes. The American Academy of Dermatology says effective treatment for hair loss begins with finding the cause, and that a board-certified dermatologist has in-depth knowledge of the many causes. [4] If the dermatologist suspects a disease, a vitamin deficiency, a hormone imbalance or an infection, you may need a blood test or scalp biopsy. [4] The academy says that if you need treatment for regrowth, the earlier you start, the more likely you are to see regrowth. [4]
On supplements, the academy is direct: if your blood test shows you are not getting enough biotin, iron or zinc, your dermatologist may recommend a supplement, and you should only take them when a blood test shows a deficiency. [4] It adds that if your levels are normal, taking a supplement can be harmful, and gives iron poisoning as its example. [4]
When to talk to your clinician
Talk to a clinician before any blood test if you take biotin in any form, so the result can be read with that in mind. [2][3] Talk to a board-certified dermatologist if your hair is thinning, rather than starting with a supplement, because the cause decides the treatment and earlier treatment gives a better chance of regrowth. [4] If a doctor has already found a deficiency, whether and how to supplement is a decision for you and that doctor. [4]
Sources
- Patel DP, Swink SM, Castelo-Soccio L. A Review of the Use of Biotin for Hair Loss. Skin Appendage Disord. 2017;3(3):166-169 (PubMed abstract, PMID 28879195). Published online April 27, 2017. Retrieved 2026-10-18.
- US Food and Drug Administration, Biotin Interference with Troponin Lab Tests - Assays Subject to Biotin Interference. Content current as of 06/21/2022. Retrieved 2026-10-18.
- NIH Office of Dietary Supplements, Biotin: Fact Sheet for Consumers. No revision date shown on the page. Retrieved 2026-10-18.
- American Academy of Dermatology, Hair loss: Diagnosis and treatment. No revision date shown on the page. Retrieved 2026-10-18.
Every statement above was checked against the linked source on the date shown. This article is education, not individual medical advice. Related: What causes hair loss in women?