" Heat rash is self-explanatory– a rash that’s caused by the heat. Most commonly, the rash forms under wet clothes during humid and hot conditions. Adults rarely suffer from heat rash, but young children can develop it very quickly. The heat rash may cause some itching and slight discomfort, but it should clear up on its own in a few days. Sunburn Did you know that it takes just 15 minutes for sun damage to ...