Acute Urticaria: Symptoms, Causes, Treatment
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Acute urticaria causes itchy raised patches that come and go for less than six weeks. Individual wheals usually disappear within a day, sometimes with deeper swelling. Breathing difficulty or throat swelling requires emergency help.
What is Acute Urticaria?
Hives do not always mean food allergy. Infection, medication or an unidentified trigger may be involved. Episodes lasting six weeks or longer require assessment as chronic urticaria.
Related reading: Bee-sting allergy and anaphylaxis.
Symptoms
Raised itchy patches change shape and location. Lips or eyelids may swell. A single lesion persisting beyond a day, especially with pain or bruising, warrants assessment for another diagnosis.
Causes
Release of chemicals including histamine causes skin swelling. Possible triggers include infections, relevant food or drug allergies and insect stings. Timing alone cannot prove causation or justify excluding entire food groups.
Risk factors
Anyone can develop acute hives. Infection and exposure to a known trigger increase some risks. Previous allergy is relevant history but does not establish the cause of every subsequent rash.
Diagnosis
Record timing, medicines, infection symptoms and relevant foods, and photograph the rash. The clinician selects allergy tests when the history supports them; broad allergy panels are unnecessary for every uncomplicated episode.
Treatment
Modern, less-sedating antihistamines are commonly used at an age-appropriate dose after advice. Cool compresses and comfortable clothing may help. Do not combine products, increase doses or start oral steroids without medical direction.
Complications
Itching may disrupt sleep and deeper swelling can occur. Hives can accompany anaphylaxis, but not every episode is anaphylaxis. Bruising, fever or joint pain require assessment beyond ordinary hives.
Prevention
Avoid confirmed triggers and keep an exposure and symptom record. Reduce heat or friction if they worsen itching. Do not stop essential treatment or adopt a restrictive diet without an agreed plan.
When to see a doctor
Tongue or throat swelling, breathing difficulty or fainting is an emergency. Use prescribed epinephrine according to the allergy plan and call emergency services; antihistamines cannot replace it. Recurrent, persistent or uncontrolled symptoms need review.