Caused by active sweat glands that become blocked by clothing or heavy lotions, heat rash usually appears on the neck, on the upper chest, and in skin folds, such as in the groin area, under the breasts, or in elbow creases.
Spot it: The small clusters of red bumps or blisters may sting or be filled with pus. Only the area that was initially irritated will show symptoms; heat rash will not spread.
Treat it: Cool the affected area, dry the skin, and let it be exposed to air. Heat rash usually goes away on its own within a day or two, but a hydrocortisone cream can help alleviate any discomfort in the meantime.
Prevent it: When it's hot out, try to keep your skin dry, and avoid tight-fitting clothing. Wear breathable, natural fabrics, and stay away from heavy lotions or creams.