There is evidence that supports the notion that taking recommended oral dosages of biotin has a positive effect on hair growth. Experts note that a deficiency in biotin leads to hair loss. However, biotin deficiencies are considered to be a rare occurrence.
Biotin is a water-soluble B vitamin found naturally in foods like egg yolks, avocados, liver, raspberries and yeast. Its role is to help the body process fatty acids into usable energy. Biotin's popularity as a hair growth aid stems from supplement manufacturers promoting it as a remedy for hair loss.
Expert opinion on the matter notes that many people are taking more than the recommended dosage of 2.5 grams per day. Biotin supplements are commonly sold in 1,000- or 5,000-microgram formulations. While these amounts exceed the daily recommendation, taking higher amounts appears to have little to no health risks. The body absorbs any biotin it needs and flushes out the rest. There is no scientific evidence that these high dosages significantly improves hair growth.
Expert dermatologist Dr. Richard Scher agrees that low levels of biotin may cause hair loss, and taking supplements may help reverse that. However, he relates his concern about possible overdosing on the supplements. Dr. Scher warns that too much biotin may cause adverse reactions, such as high blood sugar, skin rashes, slow insulin release and lower levels of vitamins B6 and C.