Is Biotin Hard on the Liver and Kidneys? Understanding Supplement Safety

November 14, 2025 •

3 min read

According to the National Institutes of Health, there is no evidence that biotin is toxic at high intakes for healthy individuals, as it is a water-soluble vitamin. This low toxicity profile is central to understanding the impact of biotin on the liver and kidneys, which are key organs involved in its metabolism and excretion.

Quick Summary

Biotin is generally considered safe and well-tolerated, even at high doses, and does not cause liver or kidney damage in healthy individuals. Concerns arise primarily from high-dose supplements interfering with specific lab test results.

Key Points

Low Toxicity: Biotin has a very low risk of toxicity, and no Tolerable Upper Intake Level has been established for it.
No Liver Damage: Biotin does not cause liver damage in healthy individuals, even at high doses. The relationship between biotin and the liver is complex, with liver disease potentially affecting biotin metabolism.
Safe for Healthy Kidneys: The kidneys efficiently excrete excess biotin due to its water-soluble nature, posing no strain on healthy kidneys.
Caution with Pre-existing Conditions: Individuals with chronic kidney disease should consult a doctor before taking biotin, as their clearance rate may be altered.
Lab Test Interference: High doses of biotin are known to interfere with lab tests, including those for thyroid function and heart attack markers, potentially leading to misdiagnosis.
Food Sources Preferred: Most people can get sufficient biotin from a balanced diet, which is the safest way to ensure adequate intake.

Biotin Metabolism and Organ Function

Biotin, also known as vitamin B7, is a water-soluble vitamin essential for several metabolic functions, including the breakdown of fats, carbohydrates, and proteins. Its water-soluble nature means that the body does not store excess amounts; instead, it excretes any unused biotin through urine. The liver plays a crucial role in biotin metabolism, while the kidneys are responsible for clearing the vitamin from the body.

The Role of the Liver

The liver contains the carboxylase enzymes that rely on biotin as a cofactor for their activity. For healthy individuals, studies have shown that even pharmacological doses of biotin do not cause liver toxicity or elevate liver enzymes. The relationship between biotin and the liver is such that liver disease can actually affect biotin metabolism, rather than the other way around. For instance, chronic liver disease has been linked to lower levels of the enzyme biotinidase, which is produced in the liver. Some animal studies have noted minor morphological changes in the liver with biotin supplementation, but these changes were not associated with liver damage. However, hair, skin, and nail supplements often contain more than just biotin. It is important to note that other ingredients, such as excessive amounts of vitamin A, may carry a risk of liver damage.

The Role of the Kidneys

As a water-soluble vitamin, any excess biotin is typically filtered by the kidneys and excreted in the urine. For individuals with healthy kidney function, this process is efficient and poses no strain on the organs. There is no evidence suggesting that biotin supplementation causes kidney stones or leads to chronic kidney disease. However, caution is advised for individuals with pre-existing kidney disease, particularly chronic kidney disease (CKD). In these cases, kidney function may be compromised, affecting the body's ability to excrete excess biotin. Consulting a healthcare provider is crucial to determine safe dosages and avoid potential complications. Some studies have also suggested that biotin may offer a protective effect on the kidneys in animal models of type 1 diabetes, but more research is needed.

The Real Risk: Biotin's Effect on Lab Tests

While direct harm to the liver and kidneys is not a primary concern for healthy individuals taking biotin, a significant and well-documented risk is its interference with laboratory test results. This is particularly true for high-dose biotin supplements, which are often marketed for hair and nail health. The biotin can affect tests that rely on a technology involving biotin and streptavidin, potentially causing falsely high or low readings.

Lab Tests Affected by High-Dose Biotin

Thyroid Function Tests: Can produce falsely high or low results, leading to misdiagnosis of thyroid conditions.
Cardiac Troponin Tests: The FDA has warned that false results on this heart attack indicator can lead to life-threatening misdiagnoses.
Hormone Assays: Tests for certain hormone levels can also be affected, impacting diagnoses and treatment plans.

To mitigate this risk, healthcare providers recommend stopping biotin supplementation for at least 48 to 72 hours before any blood tests.

Comparison: Biotin and Organ Health


Feature	Healthy Individuals	Individuals with Pre-existing Liver/Kidney Conditions
Liver Impact	Generally safe, even at high doses, with no evidence of toxicity. Biotin is metabolized efficiently.	Liver disease can impact biotin metabolism. A doctor's consultation is necessary.
Kidney Impact	Safe, as excess is effectively excreted in urine. No link to kidney stones or disease.	Clearance can be affected, especially in advanced stages of kidney disease. Medical supervision is recommended.
High Dose Effects	Primarily causes interference with lab tests. Mild digestive issues and skin rashes are possible.	Potential for increased side effects and altered clearance. High risk of lab test interference.
Recommended Intake	Adequate Intake (AI) is 30 micrograms (mcg) per day for adults. Most get enough from diet.	Needs should be discussed with a healthcare provider, as they may differ.

Conclusion: Responsible Supplementation is Key

Biotin is a safe and low-risk supplement for most healthy individuals, even at high doses, with the body effectively clearing excess amounts through the kidneys. It does not directly harm the liver or kidneys. The primary concern with high-dose biotin supplementation is its potential to cause misleading results on important lab tests. To ensure safety, it is always best to consult a healthcare provider before starting any new supplement, especially if you have pre-existing health conditions or are undergoing lab testing. For most people, a balanced diet is sufficient to meet their biotin needs without supplementation.

For more information on the role of biotin, consult the NIH's Biotin Fact Sheet for Health Professionals.

Frequently Asked Questions

There is no evidence that biotin, even in very high doses, causes liver damage in healthy individuals. The liver is where biotin metabolism occurs, but research indicates it is not toxic to the organ.

For individuals with chronic kidney disease (CKD), it is essential to consult a healthcare provider before taking biotin. While biotin doesn't cause kidney damage, the kidneys' reduced function can affect how excess biotin is cleared from the body.

No, there is no evidence to suggest that biotin supplementation causes kidney stones. As a water-soluble vitamin, excess amounts are flushed out through the urine.

High doses of biotin can interfere with certain lab tests, such as those for thyroid function and cardiac troponin, causing inaccurate results. This is due to the technology used in some assays.

Healthcare providers generally advise stopping biotin supplements for at least 48 to 72 hours before a blood test to ensure accurate results.

For most adults, an Adequate Intake (AI) of 30 micrograms (mcg) per day is recommended. However, for individuals taking high-dose supplements, consulting a doctor is advisable.

You can get biotin naturally from foods such as egg yolks, nuts, seeds, salmon, organ meats, and sweet potatoes.