A fever is always a symptom of an underlying illness, often an acute infection, and is a sign that the body's immune system is doing its job. As white blood cells do their job of fighting off an invading microbe, they release chemicals called pyrogens. These pyrogens activate the hypothalamus in the brain, which raises the body’s internal body temperature. The body does this because the higher temperature the body is, the less desirable the conditions are for microbes. When a fever is not dangerous (meaning it is not too high or lingering too long), herbs are very beneficial at supporting the body through the fever by reducing uncomfortable symptoms, boosting immune function and speeding healing time.