Headache and Fever: Is This a Sign of Infection?

A Potentially Serious Combination

Infections That May Cause Both a Headache and Fever
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Headaches are common and usually nothing to worry about. But if you have a fever in addition to a headache, please see your healthcare provider. Fever and headache can be a potentially dangerous combination.

Introduction to Headache and Fever

Headache and fever can be a sign of infection that is localized to your central nervous system, which consists of your brain and spinal cord. Examples of central nervous infections that may cause headache and fever include: meningitis, encephalitis, or a brain abscess.

Systemic or whole body infections, such as the flu or early HIV symptoms, may also cause headache and fever.

Other illnesses that may cause headache and fever and affect the whole body, but are not caused by an infection, include a number of rheumatic diseases like:

There are also rare, but very serious causes of headache and fever like subarachnoid hemorrhage, pituitary apoplexy, or a brain tumor

Let’s explore in more detail the infections that may cause headache and fever.


In addition to a severe, generalized headache and a high fever, symptoms of meningitis include neck stiffness, nausea, vomiting, confusion, and a sensitivity to light. People typically will not have all of these symptoms and that is why a doctor’s examination is critical. In the majority of people with meningitis, nuchal rigidity will be present.

Nuchal rigidity means a person cannot flex their neck (so are unable to touch their chin to their chest). Other potential symptoms of meningitis include rash, joint pains, seizures, or other neurological deficits.

In order to make the diagnosis, a person with suspected meningitis will undergo a lumbar puncture.

During a lumbar puncture, the cerebrospinal fluid (CSF) is analyzed to determine whether an infection is present and if so, what type of infection. This way the proper medication can be started right away. A person with suspected meningitis will also usually undergo laboratory studies, including blood cultures and a white blood cell count (infection-fighting cells in the body).


Encephalitis is an infection of the central nervous system that may be caused by a virus, bacteria, or fungus (similar to meningitis). It can be difficult to distinguish viral meningitis from encephalitis. The key difference is that encephalitis causes patients to have abnormalities in brain function - meaning a person will have an impaired mental status or have movement or sensory problems, even paralysis - whereas this is generally not the case in meningitis. Because the two can be so difficult to differentiate, doctors sometimes use the term “meningoencephalitis.”

Brain Abscess

A brain abscess is a rare, but potentially life-threatening condition, in which infected fluid collects in the brain.

Symptoms of a brain abscess can resemble that of meningitis or encephalitis and include: fever, headache, neck stiffness, neurological dysfunction, and confusion. The headache and confusion result from the elevated intracranial pressure that the abscess causes on the brain, as it continues to grow and take up space. 

Diagnosis is done with a CT scan of the brain, which classically shows a ring-enhancing lesion. Patients are treated with antibiotics given through the vein and sometimes surgical drainage of the abscess. Clearing of the infection is documented, usually through serial CT scans, and can take weeks to months.

Sinus Infection

A sinus headache and fever, in addition to a variety of other possible symptoms, like facial tenderness or swelling, ear pain, tooth pain, and thick nasal discharge may indicate a sinus infection. The good news is that if you have sinusitis, a week or so of antibiotics, rest, fluids, and steam should clear it up quickly.

Very rarely sinus infections lead to other complications like a brain abscess, meningitis, blood clot, or osteomyelitis - an infection of the facial bones (especially the forehead). If you are diagnosed with a sinus infection, be sure to follow up with your healthcare provider if your fever persists while taking antibiotics. 

Whole Body Infection

A systemic or whole body infection, such as influenza, commonly known as “the flu,” or infectious mononucleosis, often referred to as “kissing disease,” or mono, can cause fever and headache, as can a number of other viruses. Usually, there are other clues that help doctors confirm a systemic infection. For example, if you have the flu, you will typically have body aches and a cough, in addition to a headache and fever. If you have mono, you will have a sore throat and test positive on the monospot test, a rapid test used to diagnose infectious mononucleosis.

The Bottom Line

A headache and fever together can indicate a potentially serious medical condition. The combination of these two symptoms may indicate a localized infection, such as a sinus infection, or an infection in the central nervous system, like meningitis. Infectious causes of headache and fever may also indicate a more systemic or whole-body infection, such as the flu. 

If you have a headache and a fever, please discuss your symptoms with a healthcare provider right away.


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