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Fever in Adults


  • Fever is a rise in body temperature higher than the normal. A body temperature of more than 38.3 degrees Celsius (101 degrees Fahrenheit) may be considered as having a fever. A normal body temperature may be affected by different things, such as time of day or weather. A women's body temperatures may also be affected by her monthly period. The normal oral (mouth) temperature for an adult is 37 degrees Celsius (98.6 degrees Fahrenheit). Fever is usually caused by an infection due to germs, such as bacteria, viruses, or fungi. It may also be a result of an allergy, heat exposure, cancer or other diseases, or occur after using certain medicines. The cause of a fever may also be unknown, and may be called fever of unknown origin.
  • You may have red, warm, sweaty skin and you may feel hot when you have fever. At some point, you may feel cold and have chills. You may have nausea (upset stomach), vomiting (throwing up), or a headache. Other signs and symptoms may also be present pointing to the illness or condition causing the fever. Diagnosing the cause of fever will need a complete health history and physical exam, and blood and urine tests. Other tests may be done related to a disease or condition that may be causing your symptoms. Treatment will depend on the condition causing the fever. Treatment may include medicines and other measures to decrease your body temperature. With early diagnosis, treatment, and care, your fever may resolve without leading to further problems.


You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment.


Medicines for fever may cause unpleasant effects. Some may cause stomach bleeding or kidney problems in certain people. Medicines may not work, or may even be life-threatening. Having a fever for some time and not seeking treatment may prevent your caregiver from knowing its cause. This may be serious and you may become more sick if you are not treated. Call your caregiver if you are worried or have questions about your condition, medicine, or care.


Informed consent:

A consent form is a legal document that explains the tests, treatments, or procedures that you may need. Informed consent means you understand what will be done and can make decisions about what you want. You give your permission when you sign the consent form. You can have someone sign this form for you if you are not able to sign it. You have the right to understand your medical care in words you know. Before you sign the consent form, understand the risks and benefits of what will be done. Make sure all your questions are answered.

Cooling blanket:

This special blanket may be placed on your bed under the sheets. It may be used in addition to medicine to help decrease a high fever.


An IV (intravenous) is a small tube placed in your vein that is used to give you medicine or liquids.


You may be given the following medicines:

  • Antipyretics: This medicine is given to decrease a fever.
  • Antibiotics: This medicine is given to help treat or prevent an infection caused by bacteria.
  • Antifungal medicine: This medicine helps kill fungus that can cause illness.


You may have any of the following:

  • Blood tests: You may need blood taken to give caregivers information about how your body is working. The blood may be taken from your hand, arm, or IV.
  • Urine sample: For this test you need to urinate into a small container. You will be given instructions on how to clean your genital area before you urinate. Do not touch the inside of the cup. Follow instructions on where to place the cup of urine when you are done.
  • Culture: This is a test to grow and identify the germ that is causing your fever. Samples may be taken from your nose, throat, urine, or stool (bowel movement). A culture may also be done using blood, sputum (phlegm), or swabs from a wound. It helps caregivers learn what kind of infection you have, and what medicine is best to treat it.
  • Other tests: Other tests may be done related to a disease or condition for which fever is a symptom. This may be based on your health history, the pattern of your fever, and signs and symptoms that go with it. It may also be based on the findings your caregiver got from your physical exam. You may have any of the following:
    • Computerized tomography scan: This test is also called a CT scan. A special x-ray machine uses a computer to take pictures of your body. It may be used to look at bones, muscles, brain tissue, and blood vessels. You may be given dye by mouth or in an IV before the pictures are taken. The dye may help your caregiver see the pictures better. People who are allergic to iodine or shellfish (lobster, crab, or shrimp) may be allergic to some dyes. Tell your caregiver if you are allergic to shellfish, or have other allergies or medical conditions.
    • Echocardiogram: This test is a type of ultrasound. Sound waves are used to show the structure, movement, and blood vessels of your heart.
    • Lumbar puncture: This procedure may also be called a spinal tap. During a lumbar puncture, you will need to lie very still. Caregivers may give you medicine to make you lose feeling in a small area of your back. Caregivers will clean this area of your back. A needle will be put in, and fluid removed from around your spinal cord. The fluid will be sent to a lab for tests. The tests check for infection, bleeding around your brain and spinal cord, or other problems. Sometimes medicine may be put into your back to treat your illness.
    • Magnetic resonance imaging: This test is also called MRI. During the MRI, pictures are taken of your body. An MRI may be used to look at the brain, muscles, joints, bones, or blood vessels. You will need to lie still during a MRI. Never enter the MRI room with an oxygen tank, watch, or any other metal objects. This can cause serious injury.
    • Ultrasound: An ultrasound is a simple test that looks inside of your body. Sound waves are used to show pictures of your organs and tissues on a TV-like screen.
    • X-rays: X-rays of different parts of your body may be taken. These may include the chest (lungs and heart) or abdomen. X-rays may help caregivers look for infections or signs of other problems. You may need to have more than one x-ray done.

Vital signs:

Caregivers will check your blood pressure, heart rate, breathing rate, and temperature. They will also ask about your pain. These vital signs give caregivers information about your current health.

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Learn more about Fever in Adults (Inpatient Care)

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