Hives and Rashes in Kids: Allergy, Virus or Bug Bites?

Few things make a parent's stomach drop like pulling off a child's pajama top and finding red blotches across the belly that weren't there at bedtime. The first thought is "what did he eat?", then "what bit her?", and finally "is it contagious, and can they still go to school?". Most of the time the answer is reassuring: children's skin reacts easily, and many of these marks fade by themselves. A few, though, can't wait, and learning to spot those is the most useful thing you can take away from this article.

The medical team at the clinic put this guide together with Alief and Beechnut-area families in mind: kids who roll around on park grass, go to daycare, try new foods at grandma's house and, even in November, still run into mosquitoes near the bayous.

First things first: the glass test

Take a clear drinking glass and press it firmly against the spots. If the marks fade or vanish when you look through the glass, they "blanch". If they stay red or purple under the pressure and your child also has a fever, call 911 or go to the ER right away. That kind of rash can come with serious bloodstream infections that move within hours.

Go to the ER or call 911 as well if, along with the welts, your child:

• Has swelling of the face, lips, tongue or eyelids.
• Struggles to breathe, wheezes or suddenly can't stop coughing.
• Vomits over and over, looks pale, very limp or is hard to wake.
• Broke out minutes after a bee sting or a new food and looks unwell.

If none of that is happening, you have time to watch calmly and work out what kind of rash it is.

Welts that come and go: hives

Hives are raised pink or reddish welts, sometimes paler in the middle, and they itch a lot. Their signature move is relocating: a welt on the arm fades within a few hours while a new one pops up on the back. Often, by the time the family arrives at the visit, there's hardly anything left to show.

Many parents assume food is always to blame, but in young children a very common trigger is a virus: last week's cold or stomach bug can leave hives behind for several days. Other times there is an obvious culprit, such as a new food (egg, peanut, shellfish, strawberries), a medicine started recently, an insect bite, or even cold air or sweat.

Hives that come and go for days with no other symptoms are a nuisance rather than a danger. The clinic's allergy page lists care for hives, itchy skin and insect sting reactions that aren't life-threatening.

Rashes that ride along with a virus

These look quite different from hives. They tend to be flat pink dots or patches that itch little or not at all, and they almost always show up with other signs of an infection. A few patterns parents of little ones learn to recognize:

• The rash after the fever. A baby or child under three runs a high fever for about three days; the fever breaks and, just as everyone relaxes, pink spots appear on the chest and back. This is a common pattern with certain viruses, and the rash clears up without treatment.
• Hand, foot and mouth. Sores inside the mouth that make the child refuse food, plus small spots or blisters on the palms, the soles and sometimes the bottom. It spreads quickly through daycare classrooms.
• The slapped cheeks. The face turns bright red, as if the child had been slapped; a few days later a lacy pink pattern shows up on the arms and legs.

With these, the skin matters less than how your child is doing overall: drinking fluids, peeing, playing once the fever comes down. Before heading back to class or daycare, wait until a full day has gone by with no fever and no fever-reducing medicine.

When the skin feels like sandpaper

One rash is worth getting checked even if your child doesn't seem very sick: very fine red dots that make the skin feel rough, like sandpaper, most noticeable on the neck, armpits and groin, along with a sore throat and fever. That picture can be scarlet fever, which is a strep infection. It is confirmed with a rapid strep test, which the clinic runs during the visit with results in a few minutes. If it comes back positive, it needs treatment.

Bug bites: what a Houston backyard leaves behind

The city's humidity keeps bites coming well into the fall. Each critter leaves its own signature:

• Mosquitoes. Scattered small welts on arms, legs and face, wherever skin was left uncovered. In some children they swell quite a bit and linger for several days.
• Fire ants. Everywhere in Texas yards. They burn on contact and, by the next day, each sting turns into a bump with a white tip. That isn't pus, and it shouldn't be popped.
• Fleas or bed bugs. Bumps in clusters or in a line, often in threes, on the ankles, legs or waistline. If several people in the house wake up with the same thing, look at the bed, the couch or the family pet.

The bigger problem is usually not the bite but the scratching. A child scratching with dirty fingernails can break the skin and let bacteria in. Signs that this has happened include honey-colored crusts, a red, warm area that grows from one day to the next, or a painful lump filling with pus. A wound like that may need wound care and, if a pocket of pus has formed, abscess drainage, both done under local anesthesia when needed.

Quick comparison

What to do at home while you watch

• Snap phone photos, with the time, every time the spots change. Since hives wander, a picture beats any description.
• List anything new from the past two or three days, not just food: soap, laundry detergent, lotion, medicine, a trip to the park or the countryside.
• Trim the nails and dress your child in loose cotton so there's less scratching.
• Cool compresses or a lukewarm, not hot, bath ease the itch.
• Skip adult creams or pills and leftover remedies from a sibling unless you ask first.

When to bring your child in

Even when it isn't an emergency, it's a good idea to have the medical team take a look if the hives last more than a few days or keep coming back, if you suspect a food is setting them off, if a fever won't let up, if the rash comes with a sore throat, or if a bite looks infected.

Walking in works at our 77072 office, or you can phone first and choose a time that fits around school pickup. Bring the photos and your list of recent changes: together with a look at the skin, throat and ears, that usually sorts out the cause. Should your child need something for the itch or an infected bite, the prescription goes electronically to whichever pharmacy you pick; families without insurance pay for the visit at the front desk. What doesn't help is spending the night scrolling through rash pictures online: one direct look at your child's skin answers more than a hundred images.