Doctors are warning cancer patients to be cautious about taking biotin supplements for hair and nail growth because the vitamin can interfere with important blood tests. Although biotin, also known as vitamin B7, is often promoted online as a harmless beauty supplement, experts say it can create misleading lab results that may affect cancer care.
Biotin can falsely lower readings such as PSA and thyroid-stimulating hormone (TSH), which could hide signs of cancer recurrence or other health problems. It may also falsely raise hormone levels like estrogen and testosterone, potentially leading to delayed or incorrect treatment decisions. In emergencies, biotin can interfere with troponin tests used to diagnose heart attacks, making the situation even more dangerous.
Experts say many patients mistakenly believe “natural” supplements are always safe, even though true biotin deficiency is rare. Dr. Brittany Dulmage recommends using topical minoxidil (Rogaine) instead for treatment-related hair loss because it is FDA-approved and does not affect blood tests. Patients who still choose biotin are advised to stop taking it at least 72 hours before scheduled lab work and consult their oncology team before starting any supplement.