Prickly heat, also known as heat rash or miliaria, can occur during childhood or adulthood, but is most common in infants and very young children. Heat rash appears when sweat builds up under the skin and can’t escape properly—usually in areas where skin surfaces overlap, such as the neck, underarms, or groin. Prickly heat usually occurs in hot and humid conditions, but fever or being dressed too warmly can also trigger it.

Symptoms of Heat Rash

  • Pink, itchy rash that often develops in folds of skin that are covered—the neck, upper back, armpits, and, in babies, the diaper area (The rash is sometimes accompanied by tiny bumps or fluid-filled blisters.)
  • Mild swelling
  • A tingling sensation and rarely, intense itching or burning (severe rash)
  • Fever and chills
  • Pus discharge (due to inflammation)

What Causes Heat Rash?

When sweating is profuse, the pores leading to the ducts of the sweat glands can become blocked. This prevents the skin from releasing sweat, which is the body’s natural way of cooling off. The sweat is held within the skin, and subsequently, the rash forms.

Infants are most at risk for prickly heat because their sweat glands are still developing.

What If You Do Nothing?

Keeping your child (or yourself) cool, clean and dry, should clear up the rash completely within two to three days.

Home Remedies for Heat Rash

  • Use calamine lotion. Apply it to the worst areas to ease itching.
  • Take frequent cool or lukewarm baths. This will help cool overheated skin. Use mild soap and dry the skin thoroughly with a soft towel.


  • Stay cool. In hot and humid conditions, avoid direct sun. Try to stay in the shade or indoors during the hottest periods. If possible, put a child in an air-conditioned room; otherwise, use a fan.
  • Dress appropriately. Clothing made of cotton or other breathable fabrics should be worn to facilitate cooling and the evaporation of sweat. In cold weather, don’t overdress; dress in layers of clothing that can be removed or added to avoid overheating.
  • Keep the skin dry. Avoid greasy ointments. They can hold moisture in and further clog the pores. They also tend to keep the skin warmer. If an infant is perspiring heavily, applying a cornstarch powder can help. Put the powder into your hand first and apply sparingly to prevent inhalation, which may cause lung injury.

Beyond Home Remedies: When To Call Your Doctor

If the rash has not cleared up after three or four days despite appropriate at-home measures, or the rash has worsened or spread, or other symptoms such as fever or irritability develop, call your doctor or pediatrician.

What Your Doctor Will Do

Your doctor will check for other conditions—such as measles or chicken pox—that produce rashes and/or determine whether the rash is the result of an allergic reaction to a skin product, detergent, or new food.


The Complete Home Wellness Handbook

John Edward Swartzberg, M.D., F.A.C.P., Sheldon Margen, M.D., and the editors of the UC Berkeley Wellness Letter

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at

Published: 27 Jul 2010

Last Modified: 20 Feb 2015