How long does a fever last with a virus?

Most fevers caused by a virus last for 3 to 4 days, although some can last as little as 1 day, and others, such as one caused by Dengue fever, can last up to 10 days or more.

Viral fevers can range in temperature from 99°F (37.2°C) to over 103°F (39.4°C), depending on the underlying virus. Most people have a body temperature of about 98.6°F (37°C).

Anything higher than 100°F (37.8°C) is considered a mild fever and above 102.2°F (39°C) is considered a high fever.

In most cases, a viral fever isn’t anything to worry about. But if your fever reaches 102.2°F (39°C) or higher, it’s best to call a doctor. You should also call a doctor if you have a baby with a temperature above 100.4°F (38°C).

Most viral fevers will resolve by themselves within a few days, but while you have the fever get as much rest as possible and stay hydrated.

See a doctor urgently or go to an emergency department if you develop any of the following symptoms in conjunction with a fever, because these may indicate meningitis:

• severe headache
• stiff neck
• light hurts your eyes.

Also, contact your doctor immediately if you have a fever and you are:

• immune-deficient
• taking immune-suppressant medicines such as steroids, methotrexate, or cancer medication
• a transplant recipient
• HIV positive
• having trouble breathing
• getting confused or are unusually drowsy
• or have recently traveled overseas.