Aldehyde, Ketone, Carboxylic Acid Aldehyde: Aldehyde is an organic compound which contain formyl group. This functional group, in its structure R-CHO, consist of carboxyl centre bonded to R group and hydrogen.
1 Infections, bites and stings, infestations, chronic diseases, allergic reactions, sun exposure, and dry skin are among the numerous causes of itching.  Anti-itch creams and lotions containing camphor, menthol, phenol, pramoxine (Caladryl, Tronolane), diphenhydramine (Benadryl), or benzocaine can bring relief.
PUVA (psoralen and ultraviolet A radiation) treatment has been used for decades to treat severe psoriasis. In this combination therapy, the psoralen, taken internally, acts as a skin sensitizer.The sensitized skin affected by psoriasis can then be treated by ultraviolet A radiation.UVA is also of benefit in treating vitiligo, mycosis fungoides (cutaneous T-cell lymphoma), and graft versus host disease. The most common form of therapy combines 8-methoxypsoralen taken by mouth followed 45-60 minutes later by exposure of the skin to UVA.