Hives often develop when cells in your child’s skin release a chemical called histamine during an allergic reaction. The histamine produces swelling, redness, and itching. Here are some of the most common causes:

• Foods, such as peanuts, shellfish, tree nuts, eggs, and milk. Also food additives, such as monosodium glutamate (MSG) and artificial colorings.

• Viral infections

• Prescription and over-the-counter medicines. These include antibiotics (such as penicillin), sulfa, anticonvulsant medicines, phenobarbital, aspirin, and ibuprofen.

• Extreme heat or cold:

  • Cold-induced hives. These hives are caused by exposure to cold air or water.

  • Solar hives. These hives are caused by exposure to sunlight or light bulb light.

• Emotional stress

• Scratching the skin, continual striking of the skin, or wearing tight-fitting clothes that rub the skin (dermatographism).

• Exercise or physical activity

• In some cases hives keep coming back, but there is no known cause (chronic urticaria).

Hives are raised itchy bumps that can vary in color from pink to deep red. They come in different sizes. They sometimes spread to form large patches of swollen skin. Hives can appear on one part of the body and disappear on another in a few hours. Each hive lasts less than a day. But new hives may keep forming for days or even weeks.

Your child’s healthcare provider can diagnose hives by looking at your child’s skin and taking a full health history. Your child may also have skin tests. These look for foods or other substances that your child may be sensitive to. Blood tests may be done to rule out causes of hives not linked to allergies. But in most cases, the cause is never found.

For mild symptoms:

• Give your child an oral over-the-counter antihistamine that has diphenhydramine. Talk about this with your child's healthcare provider

• To ease itching and swelling, use calamine lotion or cool compresses. Or have your child soak in a cool bath. (Adding 2 cups of ground oatmeal to the tub may make your child more comfortable).

For more severe symptoms, your child’s healthcare provider may prescribe:

• A prescription or over-the-counter oral antihistamine to block the chemical in the body that causes allergic reactions. Your child is likely to take it every 4 to 6 hours for a few days. Some antihistamines may make your child drowsy. Some work faster than others. Ask your child’s provider which antihistamine to use and the correct dose to give your child.

• An oral steroid to ease severe swelling of the throat and airways. It’s often taken for 3 to 5 days.

• Epinephrine (adrenaline) to use in an emergency to stop a severe allergic reaction. If swelling affects your child’s breathing, call 911 right away. Your child is likely to need an injection of epinephrine to stop the allergic response.

Angioedema is a type of allergic reaction that sometimes happens along with hives. It causes swelling deep in the skin. This occurs especially around the face, lips, throat, and eyes. Swelling can make it hard to breathe. If this happens, seek medical care right away.

To help prevent hives, stay away from any substances your child is sensitive to:

• If your child has food allergies, read labels carefully. And be careful in restaurants.

• Tell your child’s healthcare provider, dentist, and pharmacist about any allergies your child has to medicines. Keep a list of alternate medicines handy.

Call 911right away if your child has hives and any of these: 

• Wheezing, or trouble breathing or swallowing

• Swelling of the lips, tongue, or throat

• Dizziness or fainting

• Loss of consciousness

• Stomach pain, cramps, vomiting, diarrhea, or bloating

• Feeling of doom