Heat and cold urticaria: what to know

Raised, itchy welts may appear where the skin was exposed or where body temperature changed. Cold water, cool air, ice, hot showers, exercise, fever, or a warm room can be relevant triggers. Welts may fade as the skin returns toward its usual temperature, but swelling can also affect deeper tissue around the lips, eyelids, hands, or feet. A clinician may ask what touched the skin, how quickly the marks appeared, and whether mouth or throat symptoms occurred. This pattern is different from an ordinary rash that stays fixed in one place.

Record the temperature exposure, timing, body area, and associated symptoms. Avoid deliberate ice or heat tests at home, because a broad reaction can be difficult to manage. Use gradual temperature changes, protective clothing in cold conditions, and lukewarm rather than very hot water. A clinician may recommend an oral antihistamine treatment plan; do not change the dose or combine products without advice. Severe flares may require a different short-term treatment selected by a professional.

Call emergency services immediately for trouble breathing, wheezing, faintness, confusion, or swelling of the tongue or throat. Seek urgent assessment after a widespread reaction, especially following cold-water immersion or a large-area exposure. Arrange a dermatology review when episodes recur, interfere with bathing or exercise, or leave persistent swelling, bruising, pain, or skin changes.

Ask whether the timing fits inducible urticaria, which exposures should be avoided, and what medication plan is appropriate for planned activities such as swimming or exercise.