What is heat rash?

If your little one suddenly develops a bright red pimply rash on his neck, under his arms or near the edges of his diaper, don't panic; it's probably just a heat rash. Heat rash, also known as prickly heat, is a red, pimply skin eruption that can appear when your child overheats due to a combination of hot weather and humidity. It shows up most often in folds of the skin and on parts of the body where clothing fits snugly including the chest, stomach, neck, crotch, and buttocks. If your child wears hats, the rash may even spread across his scalp or forehead. Heat rash most frequently affects babies because parents tend to overdress their children and they're too young to complain, but children of all ages as well as adults can get it.

What causes heat rash?

When the weather's hot, your baby sweats to cool down. If he sweats so much that his skin pores become clogged and sweat can't get out, heat rash develops. (Babies are particularly prone to heat rash because they have smaller pores than adults do.) Tight or heavy clothing can trap the sweat as well, contributing to the irritation. Heat rash can also occur when your baby has a high fever, which often causes heavy sweating.

Is it painful for my baby?

No, it isn't usually painful, but it can be annoyingly itchy and some of the pimples may be tender to the touch.

How should I treat heat rash?

Start by cooling your baby off. Loosen or remove his clothing, and move him into an airy room or shady spot. Then cool the affected areas directly, using cold wet washcloths. A tepid bath can also help. Let the air dry his skin as much as possible rather than using towels - a little nude time will help heal the rash. If your baby seems irritable and cries when you touch his skin, apply calamine lotion or hydrocortisone cream (1/2 percent) to the worst spots if your pediatrician says it's okay (newborn skin is particularly sensitive, so make sure to call your doctor before putting any kind of cream on his skin). Avoid ointments and other lotions since they can make the rash worse by trapping moisture inside the skin. If the weather stays hot at night where you live, turn on the air-conditioning or place a fan near your child's bed.
Check with your pediatrician if your baby has fever, she may recommend giving him a fever-reducing medicine to ease his discomfort. Keep an eye on your child during this time: As the fever drops, he might get chilled and need to be warmed up.

How can I prevent heat rash?

You can prevent some heat rashes by applying corn starch to your baby's body creases (avoid using talcum powder, your baby may breath in the talc and hurt his lungs causing breathing difficulties). Keep your child comfortably cool by dressing him in loose-fitting, light clothing, particularly in warm weather. Although there's no proof that one type of fabric is better than another, some dermatologists say natural fabrics such as cotton allow the skin to sweat more efficiently than do synthetics. If you aren't sure whether he's overheated, touch his skin. Damp hot skin indicates he's too warm. On a scorching day, keep your baby inside or look for cool, shady, or breezy places to sit and play outside. Make sure your baby is well-hydrated by breastfeeding or formula feeding often.

Should I take my child to the doctor for heat rash?

See your pediatrician if the rash doesn't go away after three or four days, if it appears to be getting worse, or if your child has a high fever that isn't responding to medicine or cooling techniques. Call your doctor immediately if your newborn has a rectal temperature over 100.4 degrees F; it could be a sign of a serious illness.