Biotin is a water-soluble B-vitamin that has no known side effects when taken in doses up to 10 milligrams. WebMD reports that the vitamin is regarded as safe, but it has no established recommended daily allowance, and few studies exist that analyze the effects of high doses on the body. Regardless, individuals that notice any adverse effects when taking biotin should stop taking the vitamin and contact a doctor immediately.
Biotin is commonly referred to as vitamin H. The H stands for "haar und haut," a German phrase that translates as "hair and skin," due to the significant effect of the vitamin on those parts of the body. The vitamin is a commonly recommended dietary supplement for people seeking to grow strong hair and nails. A few symptoms of biotin deficiency are hair loss, dermatitis, pink eye and neurological issues, such as depression, lethargy, numbness and even hallucination.
Foods containing significant levels of biotin include peanuts, leafy green vegetables, liver and raw egg yolk. While some foods may contain high amounts of biotin, bioavailability affects how well the body absorbs the vitamin after consumption. For example, the body only absorbs between 20 and 40 percent of biotin found in most grains.