Fever with no clear cause (fever of unknown origin)

Overview

Common causes include hidden infections, autoimmune diseases, and some cancers.

Many cases are found with careful testing.

A fever over 101 that lasts 3 weeks without a clear cause.

Infections, cancers, and autoimmune diseases are common causes.

Symptoms

Common signs:

• Fever lasting weeks

Less common

• Night sweats
• Weight loss

Look up a symptom: Fever

When to get medical care

Causes

Many causes.

Does it spread or run in families?

• It isn't contagious. You can't catch it from someone else.

Diagnosis

A clinician asks about your symptoms and may order tests.

The exam

A physical exam.

Tests

Tests, if needed:

• Blood tests:
• Scans:

Treatment

Treatment depends on the cause and how severe it is.

Self-care

• Keep a fever diary
• Drink fluids

Prevention

To lower your risk or prevent problems:

• Tell doctors about travel

Which doctor treats this

• Start with your primary care provider (family doctor or internist).

Children, pregnancy, and older adults

• Older adults: Causes differ.

Pregnancy and breastfeeding

• If you're pregnant or planning to be, tell your prenatal provider about this condition.
• Don't start or stop any medicine on your own. Some are safe in pregnancy and some need to be changed.
• Ask before taking any pain reliever. The FDA advises avoiding ibuprofen and naproxen after 20 weeks unless your doctor says to.
• Breastfeeding: Most medicines are fine, but ask. The NIH LactMed database lists what's known about each one.

Outlook

Many causes are found and treated.

Most causes are found and treated.

Getting ready for your visit

Bring a list of your symptoms and medicines.

What to bring

• A list of your medicines and supplements
• Notes on when symptoms started and what makes them better or worse

Questions to ask

• What's causing this?
• What treatment do you recommend?
• Which tests come next?

Research studies

Research studies test new ways to find and treat health problems. Some are looking for volunteers. Talk with your doctor before joining one.

Search ClinicalTrials.gov for studies on Fever with no clear cause (fever of unknown origin)