Heat rash and hives: what should you know?

Heat rash often produces small prickling bumps in areas where sweat collects, such as the neck, chest, back, skin folds, or beneath tight clothing. It tends to follow warmth, humidity, exercise, or occlusion. Hives are usually smoother, raised welts that may join together and shift to new areas; individual welts commonly fade while others appear. Swelling around the lips, eyelids, tongue, or throat is more concerning than either ordinary rash. See more about [Skin Bumps](/symptoms/skin-bumps/) and [Skin Rash](/symptoms/skin-rash/).

Move to a cooler place, loosen clothing, rinse gently with lukewarm or cool water, and pat the skin dry. Avoid heavy ointments, fragranced products, and scratching. A light, breathable layer can reduce sweat friction. For a suspected hive episode, record recent foods, medicines, insect stings, or products and ask a clinician or pharmacist which treatment is suitable. [Emollient Therapy](/treatments/medical-dermatology/emollient-therapy/) may help a dry, irritated barrier, but it does not explain every itchy eruption.

Seek emergency help for trouble breathing, throat tightness, faintness, or rapid swelling of the mouth or tongue. Arrange medical review when a rash is painful, blistered, infected-looking, spreading, recurring without a clear trigger, or not settling after cooling and gentle care. [Skin Redness](/symptoms/skin-redness/) can have causes other than heat rash.

Ask whether the pattern fits heat rash, hives, contact irritation, or another condition; which medicines or creams are appropriate; and what symptoms should prompt emergency care. Ask before using [Topical Corticosteroids](/treatments/medical-dermatology/topical-corticosteroids/), especially on thin skin or near the eyes.