What is heat rash?
Heat rash, also known as prickly heat, is a red pimply skin eruption that can appear when your child overheats. It shows up most often in folds of the skin and on parts of the body where clothing fits snugly. These places include 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, but children of all ages as well as adults can get it.
Is heat rash serious?
It's considered a mild condition -- common and not particularly serious. But heat rash is a sign that your child is too warm. If that continues, he could develop a serious condition such as heat exhaustion or heat stroke.
What causes heat rash?
When the weather's hot, the body sweats to cool down. If a child sweats so much that his body can't process the perspiration efficiently, the skin pores may become clogged, sweat can't get out, and -- voila -- heat rash develops. (This is common among children because they have smaller pores than adults do.) Heat rash can also occur when your child has a high fever, which often causes heavy sweating.
Heat rash can be annoyingly itchy. It usually isn't painful, though some of the pimples may be tender to the touch.
How should I treat heat rash?
Start by cooling your child off. Loosen or remove his clothing, and move him into an airy room or shady spot. Then cool the rashy areas directly, using wet washcloths. A tepid bath can also help. Let the air dry his skin as much as possible rather than using towels. If he complains about itching, or if he scratches and rubs his skin, apply calamine lotion to the worst spots. Use anhydrous lanolin to help prevent duct blockage and stop the rash from spreading. Avoid ointments and other lotions since they can make the rash worse. If the weather stays hot at night where you live, turn on the air-conditioning or place a fan near your child's bed.
If the heat rash is associated with fever, also give him a fever-reducing medicine. (Never give aspirin to anyone under 20 who might have a virus, since it may cause a life-threatening condition known as Reye's syndrome.) 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 cornstarch to the body creases (avoid using talcum powder). Keep your child comfortably cool. Don't overdress him, particularly in warm weather. Although there's no proof that one type of fabric is better than another, some dermatologists say it's common sense that fabrics such as cotton will allow the skin to sweat more efficiently than do synthetics.
If your child complains of feeling hot or is visibly sweating, take off some layers of clothing. If you aren't sure whether he's overheated, touch his skin. Damp hot skin indicates he's too warm.
On a scorching day, don't let your child stay outside for long periods; have him cool off indoors with air-conditioning or a fan. Or look for cool, shady, or breezy places for your child to play outside. Keep him out of direct sunlight, and limit how much he runs or plays strenuous sports in hot weather. He should also drink plenty of fluids. Water is the best choice; don't give him caffeinated soda.
When should I take my child to the doctor for heat rash?
See your pediatrician if the rash doesn't go away after a few 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. In addition, see a doctor if he has other symptoms such as a cough, enlarged lymph nodes, or muscle aches.
Mayo Clinic. Heat Rash. http://www.mayoclinic.com/health/heat-rash/DS01058
St. Louis Children's Hospital. Healing Heat Rash. http://www.stlouischildrens.org/content/healthinfo/HealingHeatRash.htm
U.S. National Library of Medicine, National Institutes of Health. Rash - child under 2 years. http://www.nlm.nih.gov/medlineplus/ency/article/003259.htm