Key takeaways:
Biotin is a nutrient that helps turn the food you eat into energy you can use. You usually get enough biotin from your diet, but you can also get it from dietary supplements when needed.
Biotin is safe to take — even at high doses. But biotin supplements can affect the results of certain blood tests.
Talk to your primary care provider if you think you’ve taken too much biotin. You can also contact Poison Control or seek immediate medical care at an emergency room.
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If you’ve looked into products that support hair, nail, or skin health, you may have found biotin supplements. And while biotin is often marketed for these uses, it’s actually an important vitamin that helps your body turn food into energy.
When it comes to taking biotin supplements, they’re generally safe — especially when you stick to the recommended amount. But can you take too much biotin? Let’s look at the science behind the side effects of biotin.
What does biotin do?
Biotin is one of the B vitamins — vitamin B7 to be exact. Biotin is an important nutrient that’s needed for your cells to work correctly. Its main job is to help create energy from the carbohydrates, fats, and proteins that you eat every day. It also helps your cells communicate with one another.
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In most cases, people get enough biotin from their diet. Meats, nuts, and certain vegetables — such as sweet potatoes and spinach — are all sources of biotin.
Biotin is also available as an over-the-counter (OTC) dietary supplement. It’s available by itself, in combination with other B vitamins, or as part of a multivitamin. It’s usually taken as an oral tablet. And it comes in doses ranging from 10 mcg to 100 mcg (0.01 mg to 0.1 mg).
Biotin is included in many supplements meant to improve hair, nail, and skin health. But there isn’t a lot of evidence that taking biotin helps with hair or nail growth, except in established cases of low biotin.
How much biotin should you take per day?
How much biotin per day is enough? It varies by age and whether you’re pregnant or nursing.
Age | Recommended daily amount |
Birth to 6 months | 5 mcg |
Infants 7-12 months | 6 mcg |
Children 1-3 years | 8 mcg |
Children 4-8 years | 12 mcg |
Children 9-13 years | 20 mcg |
Teens 14-18 years | 25 mcg |
Adults 19+ years | 30 mcg |
Pregnant people | 30 mcg |
People who are nursing | 35 mcg |
Biotin deficiency is rare. But some people can have a harder time getting the recommended daily amount of biotin. You may need more biotin if you:
Take seizure medications like carbamazepine or phenobarbital
Have alcohol use disorder
Are pregnant or nursing
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There’s also a rare genetic condition called biotinidase deficiency. It affects the way biotin is processed and recycled in your body. People with this condition need to consume more biotin to make sure they’re getting enough.
Side effects of biotin
There aren’t known side effects from taking biotin. But it’s important to note that biotin supplements can interfere with some important blood tests.
Blood tests that biotin can impact include:
Troponin levels tests: This is a blood test that’s used to help diagnose heart strain and heart attacks. Biotin can cause a false negative troponin test. This means the test results look normal when they’re not.
Thyroid hormone levels tests: Taking biotin can affect blood tests that check your thyroid gland. People taking biotin supplements may have falsely low thyroid stimulating hormone (TSH). And they can have falsely high levels of triiodothyronine (T3) or thyroxine (T4). This can lead to an incorrect diagnosis of hyperthyroidism (overactive thyroid). It can also make it more difficult to choose the right dose of thyroid medication for people with hypothyroidism (underactive thyroid).
Hormone levels tests: Biotin supplements may also affect the results of testing for other hormones, including parathyroid hormone. And it can also affect tests for reproductive hormones like follicle-stimulating hormone and luteinizing hormone.
Vitamin D levels tests: There’s evidence that biotin can affect the results of blood tests to check vitamin D levels. People taking biotin supplements may have falsely high vitamin D levels on some tests.
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Let your healthcare team know if you’re taking a biotin supplement. It’ll help them correctly interpret your test results. Or they may ask you to stop taking biotin for a few days before getting your labs done. Consuming biotin from food isn’t likely to impact blood tests.
Is it possible to overdose on biotin?
Probably not. Biotin is a water-soluble vitamin. This means that extra biotin isn’t stored in your body. Instead, extra biotin leaves the body in your urine. Because of this, it’s difficult for biotin to build up to dangerous levels if you have healthy kidneys.
To date, there haven’t been any reports of biotin toxicity, even in studies where people took very large doses of biotin. In one study, people with multiple sclerosis were treated with high doses of biotin every day. While the recommended daily dose of biotin for most adults is 30 mcg, this study used 300 mg doses. This is 10,000 times the recommended daily dose. But even with these high doses, people didn’t experience any side effects.
So far, experts haven’t found an unsafe daily dose of biotin. It’s possible that there’s no upper limit of how much biotin a person can safely take. But more research is needed to know for sure.
What should I do if I accidentally take too much biotin?
If you’ve taken a large dose of biotin, or believe you’re experiencing side effects from taking too much biotin, you should call Poison Control at 1-800-222-1222. And if your symptoms feel serious, don’t hesitate to seek immediate medical care at an emergency room.
Frequently asked questions
The best time to take biotin is whenever it works best for you. There isn’t a particular advantage to taking biotin in the morning or the evening. But as with any supplement, it’s a good idea to try to take biotin at the same time each day. If nothing else, this helps you remember to take it on a consistent basis. Biotin is a water-soluble vitamin, which means your body doesn’t store it. Any excess biotin you consume is flushed out in your urine.
Taking high amounts of biotin isn’t known to cause hair loss. But people with low levels of biotin are more likely to experience hair loss.
The best time to take biotin is whenever it works best for you. There isn’t a particular advantage to taking biotin in the morning or the evening. But as with any supplement, it’s a good idea to try to take biotin at the same time each day. If nothing else, this helps you remember to take it on a consistent basis. Biotin is a water-soluble vitamin, which means your body doesn’t store it. Any excess biotin you consume is flushed out in your urine.
Taking high amounts of biotin isn’t known to cause hair loss. But people with low levels of biotin are more likely to experience hair loss.
The bottom line
Biotin is a vitamin that helps turn the food you eat into the energy you need. Overall, biotin supplements are considered safe when used as directed. There are no documented cases of biotin overdose. But biotin supplements can affect the results of certain important blood tests. Before starting a biotin supplement, talk to a healthcare professional to make sure it’s safe for you to take.
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References
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Cervantes, A., et al. (2025). Biotin deficiency. StatPearls.
Dasgupta, A., et al. (2021). Effect of biotin on cardiac troponin I and high sensitivity cardiac troponin I assays on vista 1500 and ADVIA centaur analyzer. Annals of Clinical & Laboratory Science.
Espiritu, A. I., et al. (2021). High-dose biotin for multiple sclerosis: A systematic review and meta-analyses of randomized controlled trials. Multiple Sclerosis and Related Disorders.
Higdon, J. (2023). Biotin. Linus Pauling Institute at Oregon State University.
Li, D., et al. (2020). AACC guidance document on biotin interference in laboratory tests. Journal of Applied Laboratory Medicine.
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Nosewicz, J., et al. (2022). The epidemiology, impact, and diagnosis of micronutrient nutritional dermatoses. Part 2: B-complex vitamins. Journal of the American Academy of Dermatology.
Office of Dietary Supplements. (2021). Biotin: Fact sheet for consumers. National Institutes of Health.
Office of Dietary Supplements. (2022). Biotin: Fact sheet for health professionals. National Institutes of Health.
Rosner, I., et al. (2019). Clinically significant lab errors due to vitamin B7 (biotin) supplementation: a case report following a recent FDA warning. Cureus.
Strilić, D. Z., et al. (2024). Biotin interference with laboratory test results. Hospital Pharmacology.
Walth, C. B., et al. (2018). Response to: 'Rethinking biotin therapy for hair, nail, and skin disorders.' Journal of the American Academy of Dermatology.
