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Biotin side effects and how to avoid them

Biotin has no reported side effects, but there are interactions and considerations to be aware of when taking it as a supplement
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By | Dec. 1, 2023 Medically reviewed by Gerardo Sison, Pharm.D.
A pill bottle with an exclamation mark on the label: Biotin side effects

Key takeaways

  • Biotin supplementation generally has no serious side effects, even at high doses, with the body able to clear excess biotin through urine.

  • Claims that biotin improves hair, skin, and nail health lack substantial evidence from controlled trials, despite its popularity for these purposes.

  • Biotin can interfere with laboratory hormone function tests, potentially leading to misdiagnosis of conditions like thyroid disease.

  • While biotin is generally considered safe, it’s unnecessary for most people due to adequate dietary intake. If you’re considering supplementation, consult a healthcare professional.

In this article:

Biotin is a water-soluble vitamin also known as vitamin B7 or vitamin H. It is a common ingredient in over-the-counter dietary supplements such as multivitamins, B complex vitamins, prenatal vitamins, and postnatal vitamins. It can also be purchased separately under several product brand names such as Meribin, Mega Biotin, Biotin 5000, Natrol Biotin Beauty Extra Strength, Biotin Maximum Strength, and Super Biotin. It can also be found in a topical form that is added to some shampoos, skin creams, and nail lacquer products. 

Biotin side effects

When oral biotin is marketed for alopecia, hair health, nail strength, or general beauty purposes, it often contains high doses of biotin, typically ranging from 5–10 milligrams (mg), which may exceed the daily recommended intake. Therefore, some people may be concerned about side effects. However, there are generally no serious side effects associated with biotin supplementation, even when taken in high doses. In most people, the body clears excess biotin through the urine.

Biotin uses

Biotin’s popularity as a dietary supplement and topical treatment stems from claims that it promotes hair and nail growth and improves skin health. It is also touted as an eczema treatment. The National Institutes of Health points out that these claims have not been substantiated, as evidence for such claims involves case reports and small studies rather than controlled trials. However, thinning hair, brittle nails, and a scaly skin rash are all potential signs of biotin deficiency, giving these claims some plausibility. 

How much biotin do you need?

Other than as a beauty, hair, skin, or health treatment, most people don’t need biotin supplements because it’s often supplemented through the diet. The recommended daily allowance of dietary biotin is 30 micrograms (mcg) per day for most adults. A healthy diet should supply about 35–70 mcg of biotin per day, often making supplementation unnecessary. However, healthcare professionals may advise women who are pregnant or breastfeeding to take extra biotin to meet the needs of the developing fetus or nursing infant. 

Some people have biotin deficiency due to a rare condition called biotinidase deficiency. People with this deficiency aren’t able to get enough biotin from their diet, so they generally need to take biotin supplements. While the recommended daily allowance of biotin is 30 mcg per day, healthcare professionals prescribe or recommend high doses for people with biotin deficiency. Biotin may also be beneficial for people who experience hair loss after bariatric surgery or infants with scaly patches on the scalp. 

Biotin and hormone test interference

Biotin does not affect thyroid health or thyroid hormone levels. However, it can interfere with certain types of hormone function tests, including thyroid function tests, vitamin D tests, heart attack tests (troponin tests), and lab tests of gonadotropin hormones (the hormones that stimulate the activity of testes and ovaries). For example, biotin supplements may give false positives or false negatives on thyroid function tests. In these cases, incorrect laboratory tests may lead to misdiagnosis of thyroid issues such as hyperthyroidism, hypothyroidism, Graves’ disease, Hashimoto’s disease, and thyroid cancer. Skewed hormone test results are more likely to occur with high daily doses of biotin.

RELATED: Can you take biotin and Synthroid together?

Biotin interactions

Biotin has very few known drug interactions. All known biotin drug interactions are considered minor and involve only the body’s ability to absorb or use biotin. These include:

  • Anticonvulsants: Certain seizure medications, such as carbamazepine, may interfere with the body’s ability to absorb biotin. A healthcare provider may suggest that a person taking such medications add biotin-rich foods or supplements to their diet. This drug interaction may be more relevant to people who need daily biotin supplements because of biotin deficiency.
  • Alcohol: Alcohol can interfere with the body’s ability to absorb biotin. 
  • Smoking: Biotin levels in the blood may decrease faster in people who smoke, so any beneficial effects of taking biotin supplements may be reduced by smoking.
  • Raw egg whites: Although eggs are an excellent source of biotin, raw egg whites contain a protein called dietary avidin that interferes with the body’s ability to absorb biotin. Excessive consumption of raw egg whites may lead to biotin deficiency.

Safety measures while using biotin

Because there are no confirmed serious side effects of biotin, only basic safety precautions are necessary when taking it. Keep in mind that the supplement market is poorly regulated. Although the Food and Drug Administration has issued no general warnings for biotin, it has recalled specific products containing biotin. The reasons for these recalls include manufacturing issues, contamination with impurities, or false claims about the benefits of the product.

Here are a few safety measures to consider when taking biotin or any supplement:

1. Consult your healthcare professional

Get medical advice before taking biotin supplements. A healthcare professional may be able to direct you to quality biotin supplements made by reputable manufacturers. The main goal is to avoid problems due to different ingredients or careless manufacturing.

2. Buy biotin supplements that are approved by third-party testers

A number of organizations test supplements to verify they contain what they say they contain and are free from impurities. One place to start is to look for the United States Pharmacopeia “USP verified” mark on the package or bottle.

3. Do your research

Before adding any dietary supplement to your routine, research both the distributor and the manufacturer. Avoid purchasing supplements from a manufacturer with a history of recalls, particularly if those recalls involve poor quality or impurities.

4. Read the list of ingredients

The active ingredients list is typically simple. A biotin supplement should only have biotin, but some products may include other vitamins, minerals, or OTC drugs. In addition, the supplement may contain inactive ingredients to improve the shelf life or taste. Read the list of ingredients to scan for anything that might cause allergic reactions or side effects of their own.

5. Start with a small dose

Start with a small dose and work your way up to your desired dose. This will help you identify whether the supplement may be causing any particular problems or side effects. 

6. Keep biotin supplements away from children

As with all supplements, parents and caregivers should be cautious about giving children and teens biotin without guidance from a healthcare provider. One of the most appropriate ways to provide biotin to children and teens is through a healthy diet. Foods high in biotin include eggs, meats, seeds, and nuts. 

How to treat side effects of biotin

High doses of biotin may cause an upset stomach. However, there are no known serious side effects of biotin. Some biotin products may cause problems because of other ingredients or impurities. If any adverse effects develop while taking a biotin supplement, consider switching to a different product. If that doesn’t help, see a healthcare provider.

Bottom line: Is biotin safe?

If supplied by a reliable, quality manufacturer, biotin is typically a safe supplement to take even in high doses. However, biotin supplementation is not usually necessary since a normal and healthy diet provides adequate intake of daily biotin. There is little evidence that biotin supplements or topical products completely improve hair growth, hair health, nail health, or skin health. Although biotin may fail to deliver on some of its promises, it is generally safe to take at most doses.

 

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