Research suggests that taking high doses of biotin may lead to inaccurate thyroid lab results. Stopping biotin several days before your test can help you avoid this.

Biotin is a B-complex vitamin that supports key bodily functions such as converting food into energy. Over the years, it has gained popularity as an ingredient in beauty products for promoting healthy hair and nails.

Most people get enough biotin by eating a healthy diet — in fact, biotin deficiency is rare in the United States. Biotin can be found in foods such as egg yolks, salmon, nuts, and seeds. However, some people may choose to take biotin in the form of supplements to aid hair and nail growth.

Most biotin supplements are water-soluble and considered safe and nontoxic. However, some research has found that consuming high doses of biotin can interfere with thyroid function tests, resulting in inaccurate results. Learn more about why this happens and what you can do to avoid interference.

The American Thyroid Association reports that taking a high dose of biotin can change thyroid test results and lead to an incorrect diagnosis.

A thyroid test typically measures your levels of the hormones triiodothyronine (T3) and thyroxine (T4). Some research suggests that taking large amounts of biotin can falsely elevate these levels, trigger misleading test results, and lead to an inaccurate diagnosis of hyperthyroidism.

How much biotin can interfere with lab results?

The exact dose of biotin that may interfere with lab test results can vary from person to person. The National Institutes of Health reports that taking as little as 10 milligrams of biotin within 24 hours before a thyroid test can produce inaccurate or abnormal test results and decrease levels of thyroid-stimulating hormone.

If you’re taking a biotin supplement, there are some ways you can avoid interference with lab results, including:

  • Informing a healthcare professional: You should always tell the healthcare professional who is performing the test about all the supplements and medications you’re taking. This can allow them to be aware of any potential abnormalities in your results.
  • Temporarily stopping supplements: If you have an upcoming thyroid test, it can be helpful to stop taking supplements a few days beforehand. This can help clear excess biotin out of your system to ensure accurate test results and diagnosis. A doctor can tell you how many days beforehand to stop the supplements.
  • Trying an alternative option: If you take biotin for medical reasons, such as to help with symptoms of multiple sclerosis, consider speaking with a healthcare professional about whether an alternative option may be suitable for you. If you take biotin for medical reasons and wish to stop, you should always speak with a healthcare professional first.

In addition to biotin, many other factors can affect the accuracy of thyroid test results, including:

  • taking too much or too little thyroid medication
  • changing the time of day you take thyroid medication
  • serious health conditions such as heart attack, infection, liver disease, or kidney failure
  • trauma
  • high stress levels
  • side effects from medications, such as contraceptive pills and anticonvulsants
  • side effects from other supplements, such as those containing iodine

Most biotin supplements are water-soluble and considered safe and nontoxic. However, excessive consumption can lead to side effects such as:

If you have a thyroid condition such as hyperthyroidism or hypothyroidism and you find that your symptoms are not getting better or are worsening, it’s important to speak with a healthcare professional. They can take a closer look at your symptoms and put together a more effective treatment plan to help relieve your symptoms.

If you think you may have a thyroid condition, it’s also important to consult a healthcare professional so that they can perform any test necessary to make a diagnosis.

Does biotin interfere with thyroid tests?

The American Thyroid Association reports that taking a high dose of biotin can change thyroid test results and lead to an incorrect diagnosis.

What can throw off a thyroid blood test?

Many factors can affect the accuracy of thyroid test results, such as taking supplements that contain biotin or iodine, taking too much or too little thyroid medication, and having high stress levels.

Research suggests that taking high doses of biotin may lead to inaccurate thyroid test results. The exact amount of biotin that may interfere with lab results can vary from person to person. However, doses as low as 10 milligrams have been found to produce inaccurate or abnormal results.

Stopping biotin several days before a lab test can help you avoid this.