Heat rash, also known as miliaria, is actually what is referred to in medicine as herpes simplex. It is different from prickly heat. Herpes simplex is caused by a viral infection, specifically the herpes simplex virus. It is characterized by clusters of small blisters and often occurs at the junctions of skin and mucous membranes. It is self-limiting but tends to recur, especially when the immune system is weakened. On the other hand, prickly heat occurs in the hot summer months when high temperatures and humidity make sweat evacuation difficult, leading to narrow and blocked sweat ducts, which results in prickly heat. It is usually intensely itchy. Thus, it is advisable to avoid rapid changes in skin temperature, such as moving from sweating heavily to suddenly entering an air-conditioned environment. This can cause sweat glands to close while sweat is still being produced heavily, leading to prickly heat. Treatment for herpes simplex involves antiviral therapy, whereas treatment for prickly heat primarily involves cooling, inducing sweat, and astringent measures.