A fever indicates the body’s natural defense system is active, working to fight off an infection or illness. It is a temporary rise in body temperature above the usual range, typically considered 100.4°F (38°C) or higher when measured orally. While often uncomfortable, a fever is not an illness itself but rather a symptom that signals the immune system is responding. This elevated temperature can create an environment less favorable for pathogens, helping to inhibit their growth and reproduction.
Factors Affecting Fever Duration
The length of time a fever persists can vary significantly due to several influencing factors. The underlying cause of the fever, whether viral or bacterial, plays a substantial role, as does the general severity of the infection. An individual’s age also impacts how long a fever might last; infants and young children often have slightly higher body temperatures and their fevers can behave differently than those in adults.
The overall health status and strength of an individual’s immune system further determine fever duration. A robust immune response may resolve a fever more quickly, while a compromised immune system could lead to a prolonged fever. Other factors, such as certain medications or vaccinations, can also temporarily elevate body temperature.
Typical Lengths of Common Fevers
Fevers associated with common illnesses generally follow predictable timelines. For the common cold, a fever is often low-grade and peaks within 1 to 3 days. In children, a fever with a cold is more likely to occur in the first three days of illness.
Influenza (flu) fevers last for 3 to 4 days, sometimes up to 8 days. Viral fevers generally resolve within 3 to 7 days, though severe cases can last 7 to 10 days or longer.
Ear infections typically clear up within 3 days. For bacterial ear infections treated with antibiotics, fever should be gone within 2 days (48 hours).
When to Seek Medical Attention for a Fever
While many fevers resolve without medical intervention, specific signs warrant professional evaluation. For adults, seek medical attention if a fever reaches 103°F (39.4°C) or higher, or persists for more than 3 to 4 days despite home treatment. Immediate medical attention is advised if a fever is accompanied by a severe headache, stiff neck, rash, unusual light sensitivity, confusion, or difficulty breathing.
For infants under 3 months of age, any fever of 100.4°F (38°C) or higher rectally requires immediate medical attention. In children older than 3 months, consult a doctor if the fever is 102.2°F (39°C) or higher, lasts more than 3 to 5 days, or does not respond to fever-reducing medication. Additional reasons to seek care for a child include extreme sluggishness, continuous crying, difficulty waking, a rash, stiff neck, or signs of dehydration.