Start with over-the-counter treatments first, like a gentle moisturizer for dry skin, Hu says. And if the rash itches, use an over-the-counter cortisone cream for a week.

With sunburn, large sections of the skin will turn red, peaking at around 24 hours. Heat rashes occur in exposed, and more commonly unexposed, areas of the body.

In each case, the gel was applied once a day for 28 days. The main goal was to see if the rash improved, either by one level of severity or through better quality-of-life scores related to skin ...