Fever

Fever is a temporary elevation in body temperature, often signaling an immune response to infection. In adults, a fever is typically defined as a temperature of 100.4°F (38°C) or higher.

• Infections: Viral (flu, COVID-19), bacterial (pneumonia, urinary tract infection), parasitic (malaria).
• Inflammatory and autoimmune conditions: Rheumatoid arthritis, lupus.
• Other causes: Heat exhaustion, certain cancers, medication reactions, vaccines.
• Risk factors: Infants and young children, older adults, people with weakened immune systems, those living in or traveling to areas with endemic infectious diseases.

Adults should seek care for:

• Fever above 103°F (39.4°C)
• Fever lasting more than three days
• Fever with rash, chest pain, severe headache, shortness of breath, confusion, or stiff neck

Infants under 3 months with any fever should be evaluated immediately.