5-aminolevulinic acid is an endogenous precursor of protoporphyrin IX, which is a photosensitiser.
ALA is used topically in conjunction with blue light illumination for the treatment of some grades of actinic keratoses of the face and scalp. ALA solution is applied topically. It is not intended for application by patients or unqualified practitioners. Application should involve either scalp or face lesions, but not both simultaneously. Contact your cosmetic dermatologist for more information.