Is There Anything Bad About Biotin? The Hidden Risks of Supplementing

December 14, 2025 •

4 min read

The U.S. Food and Drug Administration (FDA) has issued warnings that high-dose biotin can cause inaccurately high or low results in a variety of medical lab tests, potentially leading to misdiagnosis or improper treatment. This reveals the most significant risk associated with biotin supplementation, a reality often overshadowed by marketing focused on hair, skin, and nails.

Quick Summary

Despite its reputation as a beauty aid, biotin supplements, especially at high doses, can severely interfere with crucial lab results, which could have dangerous health consequences.

Key Points

Dangerous Lab Test Interference: High doses of biotin can cause false readings in crucial medical tests, including those for heart attacks and thyroid function, potentially leading to misdiagnosis.
Limited Benefit for Healthy People: There is little scientific evidence that biotin supplements improve hair, skin, or nails in individuals without a pre-existing biotin deficiency.
Dietary Biotin is Sufficient: Most people get all the biotin they need from a balanced diet, making over-the-counter supplements largely unnecessary.
Communication with Healthcare Providers is Essential: Always inform your doctor about all supplements you take, especially before any lab work, so they can advise on stopping biotin temporarily.
Consider Alternative Hair and Nail Solutions: The scientific evidence points away from biotin as a miracle cure; discuss proven alternatives for hair and nail health with a dermatologist.
Biotin is not Inherently Toxic: While overdose symptoms are mild and rare, the main risk of high intake is not toxicity but rather diagnostic interference.
Some People Need It: Individuals with certain genetic conditions or those taking specific medications may genuinely need supplementation, but this should be medically supervised.

Beyond the Beauty Hype: Uncovering the Truth About Biotin

Biotin, also known as vitamin B7, is a water-soluble vitamin essential for several metabolic functions, including converting carbohydrates, fats, and proteins into energy. While it is widely available over the counter and often promoted for its alleged benefits for hair, skin, and nails, the truth is more complex. For most healthy people who obtain adequate biotin through their diet, supplementation is unnecessary and carries a hidden risk: the potential for serious medical test interference.

The Most Significant Risk: Lab Test Interference

The most dangerous aspect of high-dose biotin supplementation is its ability to skew the results of numerous medical laboratory tests. The FDA has publicly addressed this concern, following a reported case of a patient death linked to a falsely low troponin test, a critical diagnostic tool for heart attacks, that was likely affected by biotin intake. This interference affects a wide range of common tests, potentially leading to either a missed diagnosis or an incorrect one.

Thyroid Function Tests: Biotin can cause falsely low or high thyroid hormone levels, leading to a potential misdiagnosis of thyroid disease.
Cardiac Troponin Tests: Crucial for diagnosing a heart attack, troponin tests can be falsely low in the presence of high biotin, delaying life-saving treatment.
Hormone Assays: Reproductive hormone tests can also be affected, leading to inaccurate readings.
Pregnancy and Cancer Markers: Other tests, including those for certain cancers and pregnancy, are also susceptible to biotin interference.

The Mechanism Behind the Interference

The reason for this interference lies in the technology used by many lab tests, which relies on a biotin-streptavidin binding system. Biotin is a key component in this assay method. When high levels of supplemental biotin are present in a patient's sample, it can saturate the testing system, causing false readings. The results may appear falsely high or low, depending on the specific test's design. Because this interference isn't always obvious to a healthcare provider or the lab technician, it can lead to misinterpretation of a patient's clinical picture.

Other Potential Side Effects and Interactions

While the risk of lab test interference is the most serious, there are other considerations for those taking biotin.

Rare, Mild Side Effects: Though considered safe for most, some people may experience mild adverse effects, such as an upset stomach, nausea, or abdominal cramping.
Drug Interactions: Certain medications can affect biotin levels. For instance, long-term use of anticonvulsant medications (used for epilepsy) can significantly lower biotin levels in the body. Conversely, some liquid biotin supplements may contain sugar or alcohol, which could be relevant for individuals with diabetes or alcohol dependence.
High-Dose Effects: In very rare cases, extremely high doses have been linked to more severe issues, although the evidence is limited. There are also anecdotal reports of insomnia, excessive thirst, and increased urination with very high intake.

Comparison: Benefits vs. Risks


Aspect	Claims (Often Lacking Evidence)	Established Facts (Including Risks)
Hair & Nails	Promotes stronger, healthier growth in everyone.	Limited scientific evidence for benefit in healthy individuals; works for those with a rare deficiency.
General Health	Improves metabolism and energy production.	Biotin is essential for metabolism, but deficiency is extremely rare.
Toxicity	As a water-soluble vitamin, excess is harmlessly flushed out.	High doses can cause dangerous lab test interference, despite low toxicity.
Side Effects	Not known to cause side effects.	Mild side effects like nausea or cramping are possible in some individuals.

Is Supplementation Ever Necessary?

For the vast majority of healthy individuals, a varied diet provides sufficient biotin, and supplementation offers no proven advantage for hair, skin, or nails. However, certain groups may have a higher need or risk of deficiency:

Biotinidase Deficiency: People with this rare genetic disorder require biotin supplements.
Pregnant and Breastfeeding Women: These groups may have a higher biotin demand.
Long-Term Anticonvulsant Users: As mentioned, these medications can deplete biotin stores.

It is critical for these individuals to consult with a healthcare provider to determine the appropriate dosage and to manage any potential risks.

Conclusion: The Importance of Informed Decision-Making

The central takeaway regarding biotin is that while it is not inherently toxic, high-dose supplementation is not a harmless cosmetic choice. The potential for dangerous interference with medical tests is a serious and well-documented risk that cannot be ignored. For healthy individuals, the potential for harm outweighs the unproven benefits for hair and nails. The best course of action is to obtain biotin naturally through a balanced diet, which contains ample amounts for proper bodily function, and to always inform your doctor about any supplements you are taking. For those with a specific medical need for supplementation, working with a healthcare professional to manage dosage and test timing is essential for safety.

NIH Office of Dietary Supplements

Frequently Asked Questions

Yes. The FDA has warned that high doses of biotin can interfere with many types of lab tests, including those for thyroid hormones, cardiac troponins (to detect heart attacks), and hormone assays.

Most healthcare providers and testing labs recommend stopping biotin supplements for at least 72 hours before a blood test to prevent interference. Always check with your doctor for specific instructions.

Biotin is generally considered safe, and side effects are rare and typically mild. Some people have reported upset stomach, nausea, or cramping with high doses.

For healthy individuals, there is very little scientific evidence to support the use of biotin for improving hair, skin, or nails. The benefits are primarily seen in those with a rare deficiency.

No, a biotin deficiency is extremely rare in developed countries like the U.S. Biotin is present in many common foods, and the body also recycles some of its own biotin.

Yes, some medications can affect biotin levels. For instance, long-term use of anticonvulsants for epilepsy can deplete biotin stores in the body.

For most people, yes. A balanced diet that includes foods like eggs, nuts, seeds, and certain vegetables provides sufficient biotin to meet daily requirements.