Lupus and Unexplained Fevers

Reviewed by: HU Medical Review Board | Last reviewed: January 2020

Fevers that cannot be explained by an infection, cancer, or drug side-effects are common in people with lupus. Studies have found that between 36 percent and 86 percent of people with lupus experience fevers with no other cause.1

The medical term “fever of unknown origin (FUO)” is defined as a temperature higher than 101°F (38.3°C) that spikes several times over at least three weeks that cannot be explained by other health conditions. This type of fever is one of the main symptoms doctors find in new patients with active-stage lupus.1

One large study in Canada found fevers of unknown origin to be more common early in the disease and in Caucasian people with lupus.1

What causes fevers in people with lupus?

Fifty to 60 percent of fevers in people with lupus are caused by active disease.1,2 The other 40 percent tend to be the result of infections of the lungs, urinary tract, skin or sinuses; and less often, cancer.

One Chinese study found that a course of steroids lowered fevers in those with lupus. The study also found that people with lupus fever tended to have lower complement C3 levels and rate higher on a lupus disease activity score.2

Diagnosing lupus-related fevers

Your doctor will rule out the most common reasons for fever: Active lupus, Infection, cancer, or drug reactions.

People with lupus sometimes find that a low-grade fever between 98.5°F and 101°F signals an approaching flare or an oncoming illness. If you notice a pattern to when your fevers come and go, be sure to tell your doctor.3

How are lupus-related fevers treated?

Your doctor may recommend over-the-counter medicines such as nonsteroidal anti-inflammatory drugs (NSAIDs like naproxen or ibuprofen) or acetaminophen (Tylenol®) to control your fevers.4

Taking medicines that control your lupus in general, such as antimalarials and steroids, may also help control the fevers you have.

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