Can you put heat on a rash?

Why cooling makes more sense

Heat rash develops when sweat gets trapped in blocked sweat ducts, the tiny tubes that carry sweat to the skin's surface. More sweating keeps the problem going. Cooling, drying and airing out the affected skin helps it clear. Other rashes can come from irritating products, allergies or infections, so cooling is a way to relieve discomfort, not a treatment for every possible cause.45

How to use a cool compress

A clean washcloth is enough for a cool compress, so the equipment list is mercifully shorter than a skincare routine.2

1. 1Wet a clean washcloth with cold water.
2. 2Wring it out so the water does not drip.
3. 3Place it gently on the itchy area without rubbing.
4. 4For hives, leave it in place for 10 to 20 minutes. For contact dermatitis, use it for 10 to 15 minutes a few times daily.

For heat rash, a cold damp cloth or an ice pack wrapped in a tea towel can calm the prickly feeling. Apply it for up to 20 minutes. Keep the ice pack wrapped rather than placing it directly on the skin.3

Can you take a warm bath instead?

For hives, take warm, not hot, baths or showers. A warm bath with colloidal oatmeal is another option; follow the package soaking instructions. Apply cleanser gently with your hands rather than scrubbing with a washcloth or loofah. For heat rash, choose cool baths or showers. For itching without a clear diagnosis, lukewarm or oatmeal baths are options for relief.123

What else helps depends on the rash

For contact dermatitis, a rash caused by something touching your skin, avoiding the trigger is central to healing. A fragrance free moisturizer can help after washing. Test it before applying it widely, then apply it while the skin is still damp and again when the skin feels dry. A trigger can be something you touched hours or days earlier, including a product you have used for years.6

For hives, use gentle, fragrance free skincare and avoid scratching or rubbing, which can trigger more hives. An unscented product can still contain fragrance, making the front label a surprisingly poor place to finish reading. If you use an itch relief cream, follow its directions; use the prescribed one if your dermatologist has given you one.2

For heat rash, move somewhere cooler, gently wash with cool or lukewarm water, and pat dry. Leave the area uncovered or wear loose, clean clothing. Remove wet clothing and limit activities that cause sweating. Avoid products that block pores, including heavy creams and ointments. Ask a pharmacist or clinician before using a topical treatment. Get medical advice before using hydrocortisone for heat rash in children under 10.347

How long should you wait for improvement?

Most heat rash clears within a day or two after moving to a cooler environment, though it can take a few days. See a clinician if it is not improving after a few days. Most hives clear in days or weeks; hives lasting six weeks or longer need a dermatologist's assessment.247

When a rash needs medical help

Contact a clinician for severe pain, constant itching, fever, yellow or green fluid, red streaks, or warmth around the rash. Blisters around the eyes, mouth or genitals also need assessment. Get checked if a rash has not gone away after a week of treatment. Call 911 or seek immediate medical attention for a sudden rash that spreads quickly, trouble breathing or facial swelling.5