science

Does Biotin Have Side Effects? Here’s What You Need to Know

Dr. Carla Montrond Correia ND, CNS

Medically reviewed by

Dr. Carla Montrond Correia ND, CNS

5 min read

a hand holding a white leaf

Biotin is a popular supplement known as a beauty booster, but are there side effects? If so, what can you do to prevent them?

Biotin, or vitamin B7, is a water-soluble vitamin that’s not produced by the body. However, the bacteria within your gut microbiome can produce biotin. Because it’s water-soluble, biotin doesn’t stay in the body for too long. It’s a beneficial vitamin that helps cells to communicate, and it plays a role in the function of the immune system. It’s also known as a beauty supplement because of its purported benefits for skin, hair, and nails. However, further research is needed to support these claims.

Is biotin safe? What the research says

It’s reassuring to know that there’s no evidence of biotin toxicity, even at high amounts. That said, it’s still always a good idea to take recommended doses of any vitamin unless advised otherwise by your healthcare provider. There isn’t a recommended daily amount for biotin for two reasons:

  • Most healthy people don’t require supplementation with biotin.
  • There’s no upper limit recommendation, because there is no evidence of negative side effects from taking higher doses.

There is some evidence to support biotin helping with brittle nails and brittle hair.

The FDA’s stance on Biotin

The FDA came out in 2019 with a warning about biotin. However, this warning had nothing to do with any side effects of the vitamin. Instead, the statement was a warning regarding the fact that biotin may interfere with some diagnostic tests, particularly one that is used to diagnose heart attacks. If you take biotin regularly, make sure to tell your healthcare provider prior to any diagnostic tests or blood work.

What are the possible side effects of biotin

With biotin being a very popular dietary supplement, it’s important to examine the possible side effects of the supplement.

Biotin and lab values

As previously noted, biotin can interfere with the results of some lab values. High doses of biotin can result in inaccurate thyroid test results. When a diagnostic test uses biotin-streptavidin the results can be altered by biotin supplementation. Since biotin is a common ingredient in many multivitamins, it’s important to understand what is in any supplement and inform your healthcare provider before you undergo any diagnostic testing.

A good rule of thumb to keep in mind is that biotin doses over 10 mg can impact lab results for the following tests for:

  • Troponin
  • Thyroid levels
  • Vitamin D

The good news is that since biotin is a water-soluble vitamin, taking a short break from supplementing with the vitamin can remove excess levels from your system and make tests more accurate. Be sure to consult with your healthcare practitioners to determine how long of a break you will need before testing. They may want to go ahead with a test, but do a re-test in a few weeks after you stop supplementing with biotin.

Rashes

Rashes can actually be a result of a biotin deficiency. However, since biotin deficiencies are rare and the study evidence of such an occurrence is usually limited to infants, it’s important to have a dermatologist determine the cause of any rash or skin irritation you are experiencing.

Biotin and weight gain

Are weight changes while taking a biotin supplement a concern? The good news is that there are no studies that show a direct link between biotin and weight gain. However, it’s important to note that there are some animal studies that show that biotin deficiency may have an impact on blood sugar regulation which can impact weight management and metabolism over time.

Does biotin cause acne?

Wondering if biotin causes acne? No studies have shown a connection between biotin and acne. In fact, biotin may be beneficial in helping those undergoing some treatments for acne with skin drying that can occur.

How much biotin should I take?

Although the FDA does not have a recommended daily allowance for biotin, you can aim for between 30 to 100 mcg a day. Many supplements have values that are far above this, such as 10,000 mcg a day. Since biotin is not dangerous in high amounts and is processed quickly in the body, these higher amounts are safe and well tolerated.

How much biotin is too much?

When it comes to vitamins, more isn’t always better. High values of biotin don’t necessarily lead to greater results. Levels of biotin over 10 mg may impact blood tests and lab values. But if you are not anticipating any diagnostic testing, then this doesn’t need to be a concern. There isn’t an upper limit because there’s no evidence that supports the claim that high doses of biotin are dangerous.

Should I be taking biotin every day?

Most people don’t require a significant amount of biotin, and there are a variety of foods that have small amounts of the vitamin. Since biotin deficiencies are so rare, there’s not a lot of reason to make biotin a part of your daily supplementation. If you suspect a deficiency, it’s best to talk to your doctor to ensure there’s no other cause for your symptoms. Pregnant and lactating people may need more biotin than other adults. However, many prenatal vitamins already include an adequate supply.

Is it possible to have a biotin deficiency?

A biotin deficiency is very rare. There are some variables that can impact biotin levels and cause an insufficiency, which include:

  • Genetic issues
  • Some medications
  • Consistent alcohol use
  • Digestive issues
  • Consuming raw eggs (because avidin, which is present in raw eggs blocks biotin absorption)
  • Smoking

Are there any medications I should avoid on biotin?

There are no known negative interactions caused by biotin on any medication. Still, you should remember that some medications can impact the absorption of biotin. Talk to your doctor to see if a medication you are taking can cause a biotin absorption issue.

Final takeaways

Biotin supplements are very popular and are often marketed for their beneficial beauty effects on hair and nails. However, there is insufficient evidence from medical studies to show an impact on hair loss or overall nail health.

Since biotin is found in foods and is a very rare vitamin to be deficient in, there’s not significant research to support supplementation.

Conversely, biotin is not linked to any significant side effects and there is no level that has been shown to be toxic. The one side effect to note is that biotin can interfere with a handful of lab tests. Tell your doctor if you take a biotin supplement or a multivitamin (biotin is often included in those).

Since there is some evidence of biotin’s benefits and no evidence of contraindications, biotin isn’t a supplement to stress over.

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