Fever is a rise in the body's temperature above normal, usually in response to an infection or illness. It is one of the body's natural defenses against infection. High temperature acts as a line of defense, because many varieties of bacteria and viruses can't survive at higher temperatures.
Typically, a fever is not considered a problem unless it is higher than 101 degrees Fahrenheit. It is important to express concerned if a fever persists or if it is accompanied by other symptoms, such as increased heart rate, fatigue, vomiting, confusion, or rash. A fever is often accompanied by other symptoms, such as chills, aching muscles, sore throat, headache, dry cough, and loss of appetite. These are typically indicators of an infection, and should be reported to a doctor immediately.
Fevers are typically caused by an immune response to a virus or bacterial infection. In these cases, the fever is usually no cause for alarm, and will usually disappear as the body recovers. Viral infections, such as the flu, are usually accompanied by higher temperatures than bacterial infections.