Why does hives cause itchy skin?

Hives, also called urticaria, occur when immune cells in the skin release mediators such as histamine. These signals widen tiny blood vessels and allow fluid to move into nearby tissue. The result is a raised, swollen welt that may be pink, red, or similar to the surrounding skin. Nerve endings in the area respond to the same chemical activity, producing itching, tingling, or burning.

Individual welts can fade while new ones appear elsewhere. Heat, pressure, scratching, infections, medicines, foods, or no clear trigger may be involved. Itching alone has many possible causes, so it does not identify hives without the characteristic raised, shifting welts.

Keep the skin cool, wear loose clothing, and use a cool compress rather than vigorous scratching. A pharmacist or clinician can advise whether an antihistamine is suitable for you and how to use it safely. Record recent medicines, foods, illnesses, heat exposure, or pressure if episodes recur; this can help identify a pattern. Avoid a suspected trigger only after discussing the plan when the reaction was severe or the trigger is uncertain.

Get emergency help for swelling of the lips, tongue, mouth, or throat, trouble breathing, faintness, wheezing, or difficulty swallowing. Seek medical advice when hives are widespread, keep returning, bruise or hurt, or occur with fever or illness. A clinician can check whether the eruption is hives or another skin reaction.

Do the raised areas fit hives? Could a medicine, infection, pressure, heat, or another trigger be involved? Which treatment is appropriate with my other medicines? What symptoms should prompt emergency help? When should recurrent episodes be investigated?