A child who breaks out in a splotchy, raised, itchy rash that appears quickly and moves around the body over hours is almost certainly experiencing urticaria. The appearance is striking enough to alarm most parents, but the rash itself, without any associated swelling of the throat or difficulty breathing, is not dangerous.
The key task when a child has urticaria is to watch for the features that would convert it from an unpleasant but manageable allergic skin response into anaphylaxis, which is a medical emergency. These two situations look initially similar but require very different responses.
Healthbooq (healthbooq.com) covers childhood allergies and skin conditions through the early years.
What Urticaria Is
Urticaria is triggered by histamine release from mast cells in the skin. Histamine causes small blood vessels (capillaries) to become leaky: fluid escapes into the skin, producing swelling and redness. The characteristic wheals are raised, smooth, pink or red, with a pale centre in some cases, and are intensely itchy. They appear quickly, sometimes within minutes of a trigger, and individual wheals fade within 24 hours, though new ones may keep appearing.
Acute urticaria, lasting under six weeks, is the common childhood presentation. In children, the most common trigger is a viral infection: the immune response to the virus produces histamine release in the skin as a side effect. Food triggers (typically nuts, eggs, milk, fish, shellfish) are a common cause but are less frequent than viral triggers in most children. Medications (particularly ibuprofen and antibiotics) can trigger urticaria.
Chronic urticaria (lasting over six weeks) is less common and often has no identifiable trigger. It requires GP assessment and management.
Treatment
Oral antihistamines are the first-line treatment. Non-sedating antihistamines (cetirizine, loratadine) are appropriate for daytime use and are available over the counter. They reduce histamine activity and relieve the itch; they do not stop new wheals from appearing but make the existing ones more comfortable.
For more severe urticaria, a short course of oral prednisolone (steroid) may be prescribed by a GP.
Cool baths, cool (not cold) packs, and loose clothing all help with the itch symptom in the meantime.
Do not give ibuprofen during an episode of urticaria, as NSAIDs can worsen histamine release and make urticaria worse.
Angioedema
Angioedema is swelling of deeper tissue, including the lips, tongue, eyelids, and hands. It often accompanies urticaria and can look frightening. Swelling of the lips and eyelids, while alarming in appearance, is not dangerous unless it is extending to the tongue or the throat.
Swelling of the tongue or throat that causes voice changes, hoarseness, or difficulty swallowing is a warning sign for anaphylaxis and requires immediate action.
When It Is Anaphylaxis: Act Immediately
Urticaria that is accompanied by any of the following is anaphylaxis:
Throat or tongue swelling causing difficulty swallowing or a changed voice. Breathing difficulty, stridor, or wheeze. Pallor, limpness, or loss of consciousness. Rapid deterioration after a potential allergen.
Anaphylaxis requires adrenaline (epinephrine). In a child with a known allergy and a prescribed auto-injector (EpiPen, Jext, Emerade), administer it immediately. Call 999. The child should be kept lying flat (or if breathing is difficult, sitting up). A second auto-injector can be given after five minutes if there is no improvement.
If the child has not been prescribed an auto-injector and shows features of anaphylaxis, call 999 immediately.
Do not give antihistamines as a first-line treatment for anaphylaxis: they do not work fast enough and may give false reassurance while the reaction progresses.
Identifying the Trigger
After an episode of urticaria, a GP appointment is appropriate to review the episode and decide whether allergy testing is indicated. If the urticaria was clearly triggered by a specific food or medication, avoiding that trigger is important.
Skin prick testing and specific IgE blood tests can help identify allergenic triggers but have limitations: a positive test does not mean the child will definitely react, and a negative test does not guarantee safety. Interpretation is best done by a specialist.
For urticaria that appears to be triggered by a food or that was accompanied by any concerning features, a paediatric allergy referral is appropriate.
Key Takeaways
Urticaria (hives) is an itchy, raised, blotchy rash that appears and disappears within hours. It is caused by histamine release from mast cells in the skin and can have many triggers including viral infections, food, medication, physical triggers, and often no identifiable cause. Acute urticaria, lasting under six weeks, is most commonly triggered by a viral illness in children. The rash itself is not dangerous. Antihistamines reduce the itch and speed resolution. Urticaria becomes an emergency when it is accompanied by throat or tongue swelling, breathing difficulty, or cardiovascular collapse: these features indicate anaphylaxis and require immediate adrenaline (epinephrine) and a 999 call.
