Understanding Fever During an HIV Infection

Knowing When a Fever Is "Common" or Associated with HIV

Patient with thermometer
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Fever is as common in people with HIV as with anyone else in the general population. While doctors and individuals with HIV are sometimes quick to attributed a fever to the disease (or the drugs used to treat the disease), the fact is that fever is simply the body's normal response to an infection, causing inflammation that can result in an elevated temperature.

A fever is defined as a body temperature higher than 100°F (37.8°C) as measured by an oral thermometer, or 100.8°F (38.2°C) as measured by a rectal thermometer.

Where a fever becomes a concern is when it is of unknown origin (also known as pyrexia of unknown origin, or PUO), often during the later stages of HIV or just after exposure when a fever may be the only sign of a new infection.

Ways to Identify the Cause of an Unknown Fever

The cause of PUO are usually identified by eliminating all of the possibilities, both common and uncommon, in order to make a reasonable diagnosis. A PUO is typically defined as having a fever that has required:

  • Three outpatient visits
  • Three days in hospital without the discovery of cause
  • One week "intelligent and invasive" investigation

In people with HIV, PUO can often occur during primary infection as a result of acute seroconversion syndrome (ACS) or in later infection as as result of an opportunistic infection.

Similarly, certain drug events can cause sudden, severe spikes in temperature, such as the development of Stevens Johnson syndrome (SJS).

While not classically defined as a PUO (since it typically develops quickly and severely), SJS can be deadly if the early signs, including fever, are missed or minimized by the patient or treater.

Potential Causes of PUO

In persons newly infected with HIV, acute seroconversion is often missed if the patient or doctor is unable to connect the appearance of mononucleosis-like symptoms with an HIV exposure event.

Unless this connection is made, the PUO will useful resolve itself without treatment, leaving the patient fully unaware of his or her infection.

In later stage disease, as a person's immune system is progressively compromised by the virus, certain opportunistic infections (OIs) can develop, often manifesting with a PUO and other generalized symptom. Such OIs can include:

  • Pneumonia, with fever often accompanied by difficulty breathing in early disease
  • Encephalitis, with fever often accompanied by severe headaches in early disease
  • Tuberculosis, with fever often accompanied by cough and night sweats in early disease
  • Meningitis, with fever often accompanied by stiff neck and headache in early disease
  • Histoplasmosis, with fever often accompanied by enlarged glands in early disease

Mycobacterial infections such as mycobacterial avium complex (MAC) is most associated with PUO, followed by bacterial infections such as bacterial pneumonia or pneumocystis pneumonia.

While drug agents are a less common cause of PUO (since patients and doctors are usually able to link the fever with the initiation of a drug therapy), it is important to assess which drug or drugs are to blame.

Oftentimes, patients are quick to implicate their HIV drugs when, in fact, other agents are more likely to cause fever.

Among the possible drug agents:

  • Penicillin (e.g., amoxicillin)
  • Sulfonamides (e.g. trimethoprim-sulfamethoxazole)ulfanimides (e.g.,
  • Tuberculosis medication (e.g., rifampin)

Drug-drug interactions should also be investigated with a thorough review of all of the patient's medications, both prescription and non-prescription.

Dealing with a Fever

For mild fever, over-the-counter drugs such as acetaminophen (Tylenol), or nonsteroidal anti-inflammatory medications (NSAIDs) such as ibuprofen (Motrin)  or naproxen (Aleve) can usually help reduce temperatures.

If a fever persists or worsens, do not hesitate to call your doctor or visit the nearest clinic or emergency room. Cooling blankets or an ice compress can be used to lower a high fever, while a plenty of clear liquids (e.g., Gatorade, water, carbonated drinks) is recommended to prevent dehydration.

Edited by Dennis Sifris, MD and James Myhre


Holtzclaw, B. "Managing fever and febrile symptoms in HIV: evidence-based approaches." J Assoc Nurses AIDS Care. January-February 2013; 24(Supp 1):S86-S102. 

Miller, R.; Hingorami, A.; and Foley, N. "Pyrexia of undetermined origin in patients with human immunodeficiency virus infection and AIDS." Int J STD AIDS. May-June 1996; 7(3):170-175.

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