A person with a fever has an abnormally elevated body temperature over 100.4 degrees F (38 C). Elderly individuals with a fever should be managed carefully.

The following adults should be evaluated by a physician:

• An adult with a fever over 102.9 degrees F (39.4 C)
• An adult over 65 years old with a fever over 101.9 degrees F (38.8 C)
• An adult with a fever that lasts longer than 3 days

Types of fever include:

• Low-grade fever:
• Temperature less than 101 degrees F (38.3 C)
• High-grade fever:
• Temperature over 104 degrees F (40 C)

Fever can be caused by a variety of conditions. In most cases, it is due to a viral or bacterial infection.