A rash is an area of irritated or swollen skin. It might be red and itchy, bumpy, scaly, crusty or blistered. Rashes are a symptom of many different medical conditions. Things that can cause a rash include other diseases, irritating substances, allergies and your genetic makeup.

Contact dermatitis is a common cause of rashes. It causes redness, itching and burning where you have touched an irritant, such as a chemical, or something you are allergic to, like poison ivy.

Some rashes develop immediately. Others form over several days. If you scratch your rash, it might take longer to heal. The treatment for a rash usually depends on its cause. Options include moisturizers, lotions, baths, cortisone creams that relieve swelling, and antihistamines, which relieve itching.