Hives (urticaria) are raised, itchy, often pink or pale welts that can appear anywhere on the body, change shape, and move around over hours. They are a common allergic response to foods, medicines, insect stings, or contact with an allergen, although many cases of hives have no identifiable trigger or are set off by infections, heat, or stress. Individual welts usually fade within 24 hours.
Allergies can also drive other skin problems. Eczema (atopic dermatitis) causes dry, itchy, inflamed patches and can flare with allergens or irritants, and contact dermatitis produces a rash where the skin touches something it reacts to, such as nickel, fragrances, or certain plants. These tend to be more localised and longer lasting than hives.
Most mild hives can be eased with an antihistamine and by avoiding the suspected trigger. However, you should seek urgent care if hives appear together with swelling of the lips, tongue, or throat, breathing difficulty, or feeling faint, as this can signal anaphylaxis. See a doctor if hives last more than six weeks, keep returning, or are hard to control, as this needs further assessment.