High temperature caused by a fever is different from a high body temperature caused by a heat-related illness. A fever is the body's normal reaction to infection and other conditions, both minor and serious. Heat-related illnesses produce a high body temperature because the body cannot transfer heat effectively or because external heat gain is excessive.
Heat-related illnesses include:
Often, environmental and physical conditions can make it hard to stay cool. Heat-related illness is often caused or made worse by dehydration and fatigue. Exercising during hot weather, working outdoors and overdressing for the environment increase your risk. Caffeine or alcohol also increase your risk of dehydration.
Many medicines increase your risk of a heat-related illness. If you take medicines regularly, ask your doctor for advice about hot-weather activity and your risk of getting a heat-related illness.
Other things that may increase your risk of a heat-related illness include:
Most heat-related illnesses can be prevented by keeping the body cool and by avoiding dehydration in hot environments. Home treatment is usually all that is needed to treat mild heat-related illnesses. Heat exhaustion and heatstroke need immediate medical treatment.