To treat an itchy, allergic skin reaction, avoid contact with the trigger, use a cold compress, soak the skin, use anti-itch cream and wear loose clothing, advises WebMD. Skin allergies normally resolve on their own within two to three weeks.
After applying a cool compress or taking a cold shower, gently pat the affected area dry before adding a non-irritating moisturizer, instructs WebMD. A mixture of colloidal oatmeal and warm water can calm skin inflammation in some allergy sufferers, but it can cause irritation in others. Apply calamine lotion or an over-the-counter hydrocortisone cream to soothe itchy skin. If itching is severe, soak a soft, cotton undergarment in cool water, and wear it under a dry garment.
For cases of atopic dermatitis, also known as eczema, anti-inflammatory topical ointments, such as calcineurin inhibitors and topical steroids, may relieve itching, according to the American Academy of Allergy Asthma and Immunology. The doctor may prescribe antibiotics if he believes a bacterial infection is the underlying cause. For cases of hives and angiodema, oral antihistamines can help to relieve itching and prevent recurrence of the rash. Contact a doctor the moment you develop an allergic skin rash to receive proper diagnosis and treatment.