Multivitamins are associated with oral mucosal lesions. Vitamins associated with oral mucosal peeling include niacin and vitamin B6, with niacin deficiency causing oral damage such as tongue inflammation, stomatitis and gingivitis, and vitamin B6 deficiency causing dry and cracked lips and stomatitis. However, oral mucosa loss is not necessarily due to vitamin deficiency, and the exact cause should be analysed in conjunction with relevant tests.