Allergy is body's hypersensitivity reaction to an allergan in the body. Knowing what the reaction is to tablet, food, infection is important. Treating the underlying cause as withdrawal of tablet and food, and treating the infection. Then anti allergic tablets has to be given for a week at least or as prescribed by dermatologist. In severe form , hypersensitive, anaphylaxis steroid tablets have to be given. local calamine lotion preparations, and local antiallergics will help. Soothing lotions can help too