Urticaria in infants

Urticaria in infants: Causes and first aid

Urticaria (hives) is an allergic skin reaction that appears as a sudden onset of red, swollen, and intensely itchy spots or welts resembling a nettle sting. These rash elements can merge, forming large patches, and, characteristically, disappear quickly in one area and appear in another. In most cases, urticaria in infants is acute and benign, but it can sometimes be part of a life‑threatening anaphylactic reaction.

Why does urticaria occur?

Urticaria is caused by the release from skin cells of a biologically active substance — histamine. This leads to capillary dilation and increased permeability, causing redness, swelling, and itching. Most common triggers in infants:

• Viral infections. This is the most common cause of acute urticaria in children. The rash may appear on the background of, or even several days after, an upper respiratory infection.
• Food allergy. A reaction to a new complementary food (milk, eggs, nuts, fish) is the second most frequent cause. For how to safely introduce new foods, read the article "How to introduce allergens".
• Medications. Reaction to antibiotics or other drugs.
• Insect bites.

When is urticaria dangerous?

Urticaria is one of the symptoms of anaphylaxis — a severe, systemic allergic reaction. Call emergency services immediately if urticaria is accompanied by:

• Swelling of the lips, tongue, face, or throat.
• Difficulty breathing or wheezing.
• Vomiting, abdominal pain.
• Lethargy or loss of consciousness.

If urticaria is the only symptom and the child's condition is otherwise stable, it is usually sufficient to give an antihistamine prescribed by your pediatrician. Read about other allergic reactions in our guide.