What is a medicine typically used for white patches on skin?

Depends on cause: White patches could be due to vitiligo or eczema or fungal infection or caused by some allergic reaction or skin disease. Depending on the cause, it can be treated with topical steroids, Elidel (pimecrolimus) or protopic, or antifungal cream (for tinea versicolor). It's important to get a proper diagnosis of the cause of the white patches first before initiating therapy. Uv light can help with vitiligo.

White Patches: Steroid creams may be helpful in repigmenting (returning the color to) white patches, particularly if they are applied in the initial stages of the disease. Corticosteroids are a group of drugs similar to hormones such as cortisone, which are produced by the adrenal glands. See your dermatologist for a prescription.