While Drugs.com reports no adverse effects in humans taking up to 10 milligrams of biotin per day, the normal recommended adult dosage is between 30 to 100 micrograms daily. Individuals noticing any adverse reactions at any level should consult a medical provider.
While there are few reported problems with biotin supplements for people of any age, biotin shortages are rare in humans, according to Mayo Clinic. Most people receive enough biotin from diet and do not require supplements. Patients taking a biotin supplement should inform a doctor before he prescribes any new medications. Supplements have the potential to interact with medications, making it necessary to adjust dosage.