High Fever

Medically Reviewed By William C. Lloyd III, MD, FACS
Was this helpful?

What is high fever?

A high fever is when the body temperature rises above 103 degrees Fahrenheit in an adult (or above 101 degrees Fahrenheit in a child). A fever this high may indicate the presence of a serious infection that has triggered your immune system. The fever is the immune system’s attempt to kill the infection. Very rarely, however, this immune response can result in a fever high enough to cause permanent harm or even life-threatening complications due to overheating.

The causes of high fever vary, and they include such relatively routine conditions as sore throat, sinusitis, and urinary tract and other infections. Some causes may be more serious and include such conditions as appendicitis and pneumonia. In rare cases, high fevers can occur without any infection as a result of arthritis, lupus, or certain gastrointestinal and vascular disorders.

Treatment for fever may involve treating the underlying cause (usually infection). Other treatments include use of cold compresses to cool your skin, avoiding excess clothing, and medications such as acetaminophen (Tylenol) that can be effective in lowering fever.

Seek immediate medical care (call 911) if you, or someone you are with, have a high fever accompanied by other serious symptoms, such as difficulty breathing, severe abdominal pain, confusion, difficulty swallowing, stiff neck, severe headache, or dizziness.

S eek prompt medical care if your fever is persistent despite treatment or causes you concern.

What other symptoms might occur with high fever?

You may experience other symptoms with a high fever, and these vary depending on the underlying disease, disorder or condition.

Symptoms that may occur along with high fever

High fever may accompany other symptoms related to infection or inflammation including:

Other symptoms that may occur along with high fever

High fever may accompany symptoms unrelated to infection including:

  • Bloody stool
  • Butterfly-shaped rash on the face
  • Enlarged lymph nodes
  • Hair loss
  • Joint pain or swelling
  • Reduced mobility (range of motion of the joint)
  • Sores around the mouth

Serious symptoms that might indicate a life-threatening condition

In some cases, high fever may be a symptom of a life-threatening condition which should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Abnormal pupil size or nonreactivity to light
  • Abrupt and severe confusion
  • Change in level of consciousness or alertness, such as passing out or unresponsiveness
  • Difficulty breathing
  • Difficulty walking
  • Rash affecting trunk and extremities
  • Seizure
  • Severe dizziness
  • Severe headache
  • Stiff neck

What causes high fever?

Your immune system raises your body’s temperature to eliminate certain infections or to impede the growth of microorganisms that cause disease (most bacteria affecting humans flourish in normal or near normal body temperatures). While it is a natural immune response and can kill infection, high fever can be uncomfortable. Fever symptoms worsen when the body is unable to rid the body of the extra heat. Treatments are aimed at reversing the fever and helping lower the body temperature.

The most common causes of high fever are infections, such as pneumonia, meningitis, and infections of the urinary tract. In rare cases, fevers can occur without any infection as a result of arthritis, lupus, or certain gastrointestinal and vascular disorders.

Infectious causes of high fever

High fever may be caused by infections or inflammation including:

  • Appendicitis

  • Cellulitis (infection of the skin and tissues beneath the skin)

  • Encephalitis (infection or inflammation of the brain)

  • Meningitis (infection or inflammation of the sac around the brain and spinal cord)

  • Osteomyelitis (bone infection)

  • Pneumonia

  • Respiratory infection

  • Urinary tract infection

Noninfectious causes of high fever

High fever can also be caused by noninfectious conditions including:

Serious or life-threatening causes of high fever

In some cases, high fever may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

Questions for diagnosing the cause of high fever

In order to diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your high fever including:

  • How long have you had a fever?

  • What other symptoms have you had?

  • How high has your fever been?

  • Are you taking any medications?

  • Have you been exposed to anyone who is sick?

  • Where do you feel your symptoms?

  • Does anything make you feel better or worse?

What are the potential complications of high fever?

The complications of high fever depend largely on how high the fever rises, the fever’s duration, and its underlying cause. In adults, a fever of 105 degrees Fahrenheit, while high, may produce no complications, while a child with a fever that high could be at risk of serious and even life-threatening complications. In most cases when fever results from infection, complications from the cause of the infection are likely to be worse than complications from the fever itself.

Since your high fever may be due to a serious illness, it is vital to seek prompt medical attention to treat the underlying condition responsible for the fever. Once the underlying cause of your fever is diagnosed, it is very important to closely follow the treatment plan you and your doctor design specifically for you to reduce the risk of potential complications including:

  • Amputation

  • Brain damage

  • Organ failure

  • Permanent disability

  • Seizures

  • Spread of infection

Was this helpful?
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Dec 19
View All Symptoms and Conditions Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. Fever. MedlinePlus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003090.htm
  2. Fever. FamilyDoctor.org. http://familydoctor.org/online/famdocen/home/tools/symptom/503.html
  3. Collins RD. Differential Diagnosis in Primary Care, 5th ed. Philadelphia: Lippincott, Williams & Williams, 2012.
  4. Kahan S, Miller R, Smith EG (Eds.). In A Page Signs & Symptoms, 2d ed. Philadelphia: Lippincott, Williams & Williams, 2009.