Bottle of pills
Image Source: CDC, Debora Cartagena
This article was last reviewed on
This article waslast modified on August 1, 2018.

More and more people are taking biotin – also known as vitamin B7 – because they believe it will improve their hair, nails, and skin. The daily recommended intake for an adult is 30 micrograms (µg), but many biotin supplements marketed for beauty reasons contain much higher doses, ranging from 5,000 µg to 10,000 µg. And some new studies even suggest that mega doses of biotin (100,000 µg to 300,000 µg) could be used to treat diseases, such as neurodegenerative disorders like multiple sclerosis.

But biotin may interfere with some laboratory testing, causing results of tests to be either falsely high or falsely low. These inaccurate test results can cause healthcare practitioners to misdiagnose and mistreat their patients.

Laboratory professionals have known about this potential problem for some time. In late November 2017, the Food and Drug Administration (FDA) published a safety alert to make the public and healthcare practitioners more aware that biotin can "significantly interfere with certain lab tests and cause incorrect test results…" According to the safety alert, there has been "an increase in the number of reported adverse events [injuries associated with medical care], including one death, related to biotin interference with lab tests." The one death occurred when a patient taking high doses of biotin had falsely low troponin results from a troponin test known to have interference from biotin. Troponin is a biomarker that helps diagnose heart attacks.

Excess biotin in patients' blood samples can interfere with types of tests called immunoassays because many use biotin as part of the testing methodology. For example, some immunoassays use biotin to bind chemicals and other substances in the blood to the test tube so they can be measured. Excess biotin in the blood from supplements can block that binding and the substance won't be measured accurately.

Most of the published research on biotin interference covers hormone tests, such as parathyroid hormone (PTH), thyroid stimulating hormone (TSH), T4 and T3 tests, as well as tests for troponin. However, because biotin is used in so many immunoassays, scientists say it could interfere with many others.

In its Safety Communication, the FDA advises healthcare practitioners to ask their patients if they are taking any biotin supplements and inform the testing laboratory if interference from biotin is a possibility. They should also consider biotin interference as a potential reason for lab results not matching with a patient's signs and symptoms and/or suspected health condition.

One important way people can protect themselves from biotin interference with their lab tests, according to the FDA, is to know exactly what is in the supplements they are taking. It's not always obvious that a supplement contains biotin—for example, vitamins labeled for healthier hair, nails, and skin may only list biotin as an ingredient on the back label, in small print.

The FDA urges the general public to that know that biotin is found in many over-the-counter supplements in levels that may interfere with laboratory tests. Examples include:

  • B-complex vitamins
  • Coenzyme R
  • Dietary supplements for hair, skin, or nail growth
  • Multivitamins
  • Prenatal vitamins
  • Vitamin B7 supplements
  • Vitamin H

Patients should tell their healthcare practitioners if they are taking or plan to take biotin or a supplement containing biotin, and consider the possibility that biotin was the cause of test results that don't seem to make sense. Healthcare practitioners may advise their patients to discontinue taking biotin supplements a few days before having lab tests done.

The FDA will continue to monitor reports of adverse events of biotin interference with immunoassays and will update the public if significant new information becomes available.

View Sources

(28 November 2017) Food and Drug Administration. Biotin (Vitamin B7): Safety Communication – May Interfere with Lab Tests. Available online at www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm586641.htm. Accessed on December 4, 2017.

(January 2016) Seaborg, E. Thyroid Month: Beware of Biotin. Endocrine News. Available online at https://endocrinenews.endocrine.org/january-2016-thyroid-month-beware-of-biotin/. Accessed on December 4, 2017.

(3 October 2017) National Institutes of Health, Office of Dietary Supplements. Biotin Fact Sheet for Consumers. Available online at https://ods.od.nih.gov/factsheets/Biotin-Consumer/. Accessed on December 4, 2017.

(December 1, 2016) Barbesino, G. The Unintended Consequences of Biotin Supplementation: Spurious Immunoassay Results Lead to Misdiagnoses. Clinical Laboratory News. Available online at https://www.aacc.org/publications/cln/articles/2016/december/bench-matters-december-2016. Accessed December 2017.