Allergic contact dermatitis from vitamins: A systematic review.

ACD to vitamins is still probably an underestimated issue in cosmetology, as many vitamins are considered "natural" and therefore "safe" ingredients. On the contrary, according to current literature, almost all vitamins contained in topical products are able to induce allergic reactions, with the exception of vitamin B2 and vitamin B9. Patch tests are not standardized, thus leading to difficulties in diagnosis.