New Delhi, July 26 -- A fever-defined as a temperature above 100degF (38degC)-is usually your body's way of fighting off a viral or bacterial infection. Most mild fevers clear up within a few days with plenty of rest, hydration, and basic treatment for the underlying infection.

But if you have it for more than three days, this could signal an underlying illness that needs medical care. Here, experts explain why all cases of extended fever should never be overlooked, how to know whether it is serious and when you should see a doctor.

In many cases of viral illness, the normal recovery time is 2 to 3 days, depending on rest and adequate hydration, along with a clinical plan. On the other hand, a persistent fever may require medical interv...