If you develop red patches on your skin due to heat, you likely have heat rash, also called "prickly heat." Heat rash can occur in people of all ages, but it often affects babies and young children. Because heat rashes can become infected or worsen, you should seek medical attention if the red patches don't subside.
Heat rash occurs when the weather is hot and humid, causing your sweat-gland ducts to become clogged or blocked and trapping the sweat beneath your skin, MayoClinic.com explains. Heat rash occurs as patches of red or pinkish pimple-like dots on your skin that occurs in patches, says the University of Michigan Health System. The rash often develops on the shoulders, head and neck, as well as your thighs and torso. Heat rash can cause symptoms like tiny blisters, big red patches, a prickling sensation or irritation and itching, notes the University of Maryland Medical Center. You may experience only one, some or all of these symptoms with heat rash.
The biggest risk factor for heat rash is exposure to hot, humid weather conditions like a tropical climate, says MayoClinic.com. Newborn infants and people who're performing physical activities that cause excessive sweating are also at a higher risk for heat rash. Wearing too many clothes in hot weather can cause heat rash, because the red patches typically arise on parts of your body that are covered by clothing, notes the University of Michigan Health System. Wearing clothing that doesn't allow sweat and moisture to leave your skin pores can also cause heat rash.
Heat rash usually resolves on its own within a day or two without any special treatment. In rare cases, heat rash can lead to a secondary skin infection that requires medical attention, says the University of Michigan Health System. Signs of an infection include warmth, swelling, pus and pain around the red skin patches, a fever higher than 100 degrees Fahrenheit, and red streaks on your skin around the heat rash area.
Heat rash can also occur in conjunction with heat exhaustion, a condition caused by overheating of your body and involving nausea, headache, rapid heartbeat, dizziness and low blood pressure, MayoClinic.com notes. Heatstroke is a more severe form of heat exhaustion that can potentially lead to death. If you have signs of an infection or symptoms of heat exhaustion, seek medical attention right away.
If your heat rash doesn't clear up within three days, you may need medical treatment, warns the University of Michigan Health System. Your doctor may recommend topical treatments like calamine lotion or anhydrous lanolin to ease your itching and prevent the heat rash from spreading, MayoClinic.com says. Staying in cool, dry air can also help treat heat rash. If you have a more serious case of heat rash, your physician may instruct you to use a corticosteroid lotion on your skin, notes the University of Maryland Medical Center. Don't apply any lotions or ointments to your heat rash without first consulting a healthcare professional, however.
Because children and newborn infants are at a high risk for heat rash, you should avoid "over-dressing" your child during hot weather, warns the University of Michigan Health System. Ensure that your child wears the lightest and fewest clothes possible when the temperatures are hot and keep your infant's skin cool and dry. Sleep in a cool, airy room, dress in lightweight cotton clothes and avoid wearing tight clothing when the weather is hot and humid, MayoClinic.com recommends. You can also prevent heat rash by avoiding the use of ointments, creams and other topical skin products that block your pores.