Hives or urticaria are well-defined, itchy, red, raised lesions with a pale center that can be as small as a bug bite or large enough to cover a whole body part. They can also coalesce to form bigger lesions.
Sometimes, they can be associated with swelling (also known as angioedema) that typically occurs around the eyes or lips, but can occur anywhere in your child's body. Most hives disappear within a few hours to days and respond well to treatment.
About 25% of the population will experience hives, so your child is not alone. A lot of times, the cause will not be discovered. This is okay if it is not recurring.
Here are a few of the more common causes in children:
viral infections (especially if it is associated with a fever)
food (nuts, shellfish, and berries are common culprits)
medications (even ibuprofen can cause hives)
insect bites (bees and wasps)
physical contact (latex which you not only find in gloves but also in balloons, heat, pressure such as sleeping on your cheek then having it red and itchy a few hours after you wake up, new clothing, new lotions and so on)
Knowing what caused the hives will help you avoid the trigger next time. Trying some diphenhydramine (Benadryl) will also help. Make sure you follow the package inserts for dosing your child appropriately.
Visit your doctor if:
the hives last more than six weeks
your child has angioedema and is developing shortness of breath
your child has nausea and vomiting
the hives were caused by an insect bite as your child may need a prescription for an epipen in the future.