Doctors warn this popular vitamin may quietly disrupt cancer care

Many cancer patients turn to biotin supplements hoping to restore hair lost during treatment, but experts warn the popular vitamin may do more harm than good. While biotin is often marketed for stronger hair and nails, there’s little evidence it actually helps cancer-related hair loss—and it can dangerously interfere with lab tests. Doctors say the supplement can distort key blood markers, potentially masking cancer recurrence or delaying treatment decisions.