Heat rash typically appears as tiny raised bumps or spots on the skin, often 1 to 4 millimeters wide. These bumps can look red on lighter skin tones and grey, white, or darker on darker skin tones. Some bumps may be filled with clear fluid, resembling small blisters or beads of sweat
. There are different types of heat rash with slightly varied appearances:
- Miliaria crystallina: Tiny, clear, fluid-filled bumps that look like sweat droplets; usually mild and often seen in newborns
- Miliaria rubra (prickly heat): Small, inflamed, red bumps that may itch or cause a prickly sensation; sometimes the bumps can break open or fill with pus (miliaria pustulosa)
- Miliaria profunda: Larger, firmer, skin-colored bumps that may be painful or itchy, affecting deeper skin layers; less common and can appear after repeated episodes of heat rash
Heat rash often develops in areas where sweat accumulates and airflow is limited, such as skin folds, under the breasts, groin, neck, chest, elbow creases, and back. In infants, it commonly appears on the neck, shoulders, chest, face, and skin folds
. The rash can cause discomfort including itching, prickling, or a stinging sensation, which may lead to scratching and potential infection if the skin breaks
. In summary, heat rash looks like clusters of small bumps or blisters, red or discolored depending on skin tone, often in sweat-prone areas, and may be itchy or prickly
