What should you know about large welts on skin?

Hives are raised, itchy areas that may appear suddenly and change shape or location. They can follow an infection, medicine, food, heat, pressure, or another trigger, although a clear cause is not always found. Individual welts often fade while new ones appear elsewhere.

Swelling deeper under the skin can affect the lips, eyelids, hands, feet, or throat. A rash that is painful, bruised-looking, blistered, or fixed in one place may need a different evaluation than typical hives.

Note when the welts began, where they spread, possible new foods or medicines, recent illness, heat, exercise, pressure, and insect exposure. Take clear photographs because the appearance may change before an appointment. Avoid a suspected trigger and use only treatments suitable for you, following a pharmacist or clinician's advice.

Loose clothing and cool compresses may reduce irritation. Do not scratch, and do not start oral corticosteroids without medical direction. A clinician may consider antihistamine treatment after reviewing your symptoms and medicines.

Call emergency services for trouble breathing, throat or tongue swelling, faintness, confusion, or difficulty swallowing. Seek prompt medical advice for rapidly increasing swelling, fever, painful skin, blistering, purple or bruised-looking marks, or welts that keep recurring. Sudden facial swelling deserves particular attention because it can involve deeper tissues.

Ask whether the appearance fits hives, angioedema, or another rash; which triggers are plausible; which medicines are safe with your conditions; and what symptoms should prompt emergency care. Bring photographs and a list of recent medicines, supplements, foods, and illnesses.