What Is Heat Rash?
Heat rash is typically seen in young children or infants, but it can occasionally occur in athletes who sweat while exercising in hot and humid conditions. This skin irritation looks like any other rash, but is caused by blocked sweat ducts that become red, irritated and itchy. When perspiration can't escape through the sweat glands, little red bumps and even blisters develop. This rash can be itchy or prickly and is sometimes called "prickly heat." It commonly occurs where two body parts rub together, such as the inner thighs.How Is Heat Rash Treated?
A heat rash will usually go away on its own when you move to a cool, dry place. It's important to avoid sweating and keep the rash dry. Powders, creams or ointments should not be used on a heat rash because they can block pores and make the heat rash worse. Calamine lotion and Vitamin C supplements are sometimes recommended to help reduce itching.If a heat rash gets worse or continues more than three days it may be time to visit a physician for treatment.
Source:
Heat Rash, Patient Information, Mayo Foundation for Medical Education and Research (MFMER), 2009.

