Biotin (B7 or vitamin H) is a water-soluble vitamin, which has received publicity for promoting the growth of hair and nails. There are limited studies, which confirm the exact indications of biotin. Biotinidase deficiency is uncommon but has been documented. Frank deficiency of biotinidase may present as conjunctivitis, ataxia, seizure, skin infections, and developmental delay in children. Biotin may have benefits in those suffering from pathologic brittle hair syndrome or uncombable hair syndrome. Otherwise, indications for supplementation remain unnecessary in healthy individuals. Biotin deficiencies would require inborn errors of metabolism. Documentation on supplementation in healthy individuals remains unclear. To date, there have been no trials supporting claims of biotin supplementation being used to improve hair quality or quantity or nail growth. The U.S. Food and Drug Administration does not recommend daily biotin usage, although patients who are breastfeeding or pregnant are recommended take from 5 mcg/ to 35 mcg/day. Pregnancy and smoking increase the metabolism of biotin and would require increased intake, although controversial. There is limited evidence to suggest biotin can provide a benefit with hair and nail growth.