Biotin, also referred to as vitamin H, is a water-soluble B vitamin. The body only needs a very small amount of biotin. Biotin is shown to be effective in treating brittle finger and toe nails. There's even evidences to show that it might be helpful in reducing the symptoms of nerve problems (peripheral neuropathy) in those suffering from diabetes.
Biotin deficiency is very rare indeed. Experts suggest that the body only needs about 30 microgram (mcg) daily of biotin.
Side effects from taking biotin have not been reported. Even extremely high doses of biotin (10,000 mcg or 10 milligrams) used in animals and humans did not result in any significant side effects.
Rest assured that taking too much biotin would not cause any problems based on the research studies that are available. However, it is important to take high doses of biotin under the supervision of a healthcare professional.