Biotin tablets are not known to cause side effects when amounts of up to 10 milligrams per day are ingested, according to Mayo Clinic. Biotin is a B-complex vitamin that functions as a component of enzymes which breaks down carbohydrates, fats and other substances, explains WebMD.
The Food and Drug Administration explains that it has not established a recommended daily allowance for biotin, but the diet of an average adult may provide 30 to 40 micrograms or more of biotin per day. Biotin tablets are used to prevent and reverse biotin deficiency, notes WebMD. Symptoms of biotin deficiency include thinning and color loss of hair and a red scaly rash around the mouth, eyes and nose. Symptoms may also include hallucinations, tingling of the extremities, depression and listlessness.