At what body temperature do you have a fever?

An oral temperature of more than 100.4 degrees Fahrenheit is considered to be a fever, according to WebMD. A normal body temperature is approximately 98.6 degrees Fahrenheit, which may vary by 1 degree from individual to individual and can change depending on various factors, such as physical activity.

WebMD explains that fevers can be caused by infections; certain medications that specifically raise body temperature; other medications that impair the body's ability to regulate body temperature; severe trauma or injury; and other conditions, including arthritis, hyperthyroidism, and certain forms of cancer. An abnormally high body temperature called heatstroke can occur as a result of exposure to heat or excessive physical exertion.