An increase in temperature often means an increase in skin irritation for many babies. Heat rash, or prickly heat, is troublesome, but in most cases preventable. Heat rash is defined by a red, pimply rash that most often appears in the creases of your child's skin and on parts of the body where clothing fits tightly (chest, neck, stomach, and buttocks). It is harmless but signals that your baby is dressed too warmly.
If you notice your child breaking out in prickly heat, loosen clothing and move her to the shade or a cool room. Help lower her temperature by using a cool, wet washcloth or bath (adding ground oatmeal or baking soda can help alleviate this uncomfortable rash in older babies and toddlers). And if your child seems especially sensitive when you touch her skin, ask your pediatrician if you can apply calamine lotion, a one-half–percent hydrocortisone cream, or pure aloe vera gel to the most irritated spots (be sure to check with your doctor first before applying anything to your baby's skin).
If your child's rash doesn't dissipate in three to four days, or if it seems to get worse and is accompanied by a fever (a rectal temperature of 100.4 degrees Fahrenheit) that doesn't respond to cooling techniques, call your doctor—these symptoms may be signs of something more serious than heat rash.