Are There Any Negative Side Effects of Biotin?

December 25, 2025 •

4 min read

According to the Food and Drug Administration (FDA), high doses of biotin can cause dangerously misleading results in certain lab tests, including those for heart health. This serious risk is a critical negative side effect of biotin that people often overlook when taking supplements marketed for hair, skin, and nails.

Quick Summary

This article explains the most significant risks associated with biotin supplements, focusing on the potential for inaccurate lab test results and milder adverse effects like digestive upset and acne. It provides guidance on safe supplementation practices and when to consult a doctor, especially concerning high-dose products and pre-existing health conditions.

Key Points

Lab Test Interference: High-dose biotin can cause falsely high or low results in critical lab tests, including those for heart attacks and thyroid function, a risk that has led to misdiagnoses.
Digestive Side Effects: Mild gastrointestinal issues such as nausea, cramping, and diarrhea can occur, particularly when taking high doses without food.
Acne Breakouts: High biotin intake may interfere with the absorption of vitamin B5 (pantothenic acid), potentially triggering or worsening acne in some individuals.
Drug Interactions: Certain medications, such as some anti-seizure drugs, can lower biotin levels, while high biotin doses can interfere with how the liver processes other medicines.
Consult a Doctor: It is crucial to inform your doctor about biotin supplements before any medical tests or if you have pre-existing conditions like kidney disease or diabetes.
Diet Over Supplements: Most healthy people get enough biotin from a balanced diet, and supplementing is often unnecessary and carries more risks than dietary intake.

Biotin's Most Significant Risk: Lab Test Interference

While biotin is a vital nutrient, its most serious and potentially life-threatening side effect is its ability to interfere with a wide range of laboratory tests. The FDA has issued safety alerts regarding this issue, noting that excess biotin from supplements can cause falsely high or low test results.

How Biotin Skews Medical Tests

Many modern lab tests, known as immunoassays, use biotin-streptavidin technology to detect various biomarkers. When a patient has excess biotin in their bloodstream from a high-dose supplement, it can disrupt this binding process, leading to inaccurate readings. The false results could lead to a misdiagnosis or inappropriate treatment for serious conditions.

Commonly affected tests include:

Cardiac Tests: Troponin tests, used to diagnose a heart attack, can show falsely low results, leading to a missed diagnosis. The FDA has noted at least one death associated with this type of interference.
Thyroid Function Tests: Biotin can cause falsely high or low results for thyroid hormones (TSH, T3, T4), potentially leading to a misdiagnosis of hyperthyroidism or incorrect medication dosage.
Hormone Tests: Other hormone tests, such as those for reproductive and parathyroid hormones, can also be affected.
Vitamin D Tests: Some vitamin D level tests can show falsely high readings.

Preventing Lab Test Interference

Inform Your Doctor: Always tell your healthcare provider about all supplements, including biotin, before any lab work.
Stop Supplementation: Your doctor may advise you to stop taking biotin for at least 72 hours before a blood test to ensure accurate results.
Read Labels: Be aware that biotin is present in many multivitamins and supplements for hair, skin, and nails, often in doses far exceeding the daily recommended amount.

Potential Mild Biotin Side Effects

Beyond the critical issue of lab test interference, some individuals may experience milder, more common side effects from biotin supplementation. Since biotin is a water-soluble vitamin, any excess is typically excreted through urine, but very high doses can still cause adverse reactions.

Digestive Discomfort

Some users report gastrointestinal issues, especially when taking high doses on an empty stomach. These can include:

Nausea
Cramping or abdominal pain
Diarrhea

Biotin and Skin Issues: The Acne Connection

Despite its reputation for improving skin health, some people experience an increase in acne breakouts after starting biotin supplements. The proposed link is an imbalance with other B vitamins, specifically pantothenic acid (vitamin B5). High biotin intake may disrupt the absorption of vitamin B5, potentially affecting sebum production and contributing to acne.

Other Rare or Uncommon Side Effects

Allergic Reactions: Although rare, allergic reactions are possible, presenting as hives, skin rashes, or swelling of the face and throat.
Excessive Thirst and Urination: In rare cases of very high intake, overdose symptoms like excessive thirst and frequent urination can occur.
Insomnia: Some reports link very high biotin doses to insomnia, possibly due to its role in energy metabolism.

Biotin Supplementation vs. Dietary Intake

The distinction between biotin intake from food and from high-dose supplements is crucial. Most people obtain sufficient biotin from a balanced diet, and dietary intake is unlikely to cause negative side effects. Supplementation, however, often involves doses hundreds or even thousands of times higher than what is found in food.


Feature	Biotin from Food	High-Dose Biotin Supplements
Dosage	Generally adequate for metabolic needs (~30 mcg/day).	Often contains thousands of micrograms (e.g., 5,000 mcg or more).
Lab Test Interference	Not typically a concern.	Significant risk of skewing test results.
Side Effects	Excess is simply excreted, and toxicity is extremely rare.	Increased risk of digestive issues, acne, and other adverse effects.
Source	Biotin-rich foods like egg yolks, nuts, and seeds.	Pills, gummies, liquids, and multivitamins.
Effectiveness	Supports essential metabolic functions.	Limited evidence to support hair, skin, and nail claims in healthy individuals.

Conclusion: Informed Caution is Key

While biotin is an essential nutrient, high-dose supplementation carries significant and often overlooked risks. The most critical concern is its proven interference with numerous medical lab tests, which can lead to life-threatening misdiagnoses. Milder side effects, such as digestive issues and potential acne flare-ups, are also associated with high intake. For the average healthy person, getting biotin from dietary sources is sufficient and safe. Anyone considering a high-dose supplement should first consult a healthcare professional, especially if they have upcoming lab tests or pre-existing health conditions, to ensure proper and safe usage. Awareness and communication are the best tools for minimizing any negative side effects of biotin.

How to Minimize the Risks

Talk to your doctor: Discuss all supplements with your healthcare provider, especially before blood tests.
Choose a lower dose: If you do choose a supplement, opt for a low-dose product to reduce potential risks.
Take with food: Taking biotin supplements with a meal can help minimize any digestive upset.
Discontinue before testing: Stop taking high-dose biotin at least 72 hours before any lab tests that could be affected.
Eat biotin-rich foods: Focus on getting biotin naturally from your diet through foods like eggs, nuts, and salmon.

Frequently Asked Questions

While biotin itself is generally not considered toxic, high doses can be dangerous due to its potential to interfere with critical medical lab tests, leading to incorrect diagnoses for serious conditions like heart attacks or thyroid disease.

Healthcare providers generally recommend stopping high-dose biotin supplements at least 72 hours (3 days) before a scheduled blood test. For a more personalized recommendation, it is best to consult your doctor.

Some believe that high doses of biotin may compete with and reduce the absorption of vitamin B5 (pantothenic acid). This potential imbalance could affect skin's oil production and lead to clogged pores and breakouts, particularly for those with acne-prone skin.

Serious side effects from biotin are rare, but milder effects like digestive upset or skin issues can occur, especially with high-dose supplementation. The most common and serious risk is the interference with lab test results, which depends on both dose and the specific test.

While biotin's effect on metabolism may contribute to weight changes in some cases, there is no strong evidence linking biotin supplementation to unintended weight gain or loss. Any such effect is considered rare and requires more research.

For most healthy individuals, a balanced diet that includes biotin-rich foods like egg yolks, nuts, and meat provides sufficient amounts of the vitamin. Supplementation is typically unnecessary unless a deficiency is diagnosed.

Biotin is important for fetal development, but pregnant individuals should always consult their healthcare provider before taking supplements. Excessive amounts should be avoided, and the proper dosage should be determined by a doctor.