Causes of Fever

Infection

• Most fevers are caused by a new infection. Viruses cause 10 times more infections than bacteria. The number of germs that cause an infection are in the hundreds. Only a few common ones will be listed below.
• Viral Infections. Colds, flu and other viral infections are the most common cause. Fever may be the only symptom for the first 24 hours. The start of other viral symptoms (runny nose, cough, loose stools) is often delayed. Viral infections can range from mild (goes away on its own after a day or two) to serious and sometimes life threatening. Antibiotics are not helpful for viral infections. They will not kill viruses.
• Bacterial Infections.
  • Common bacterial infections include:
    • bladder and kidney infection
    • ear, sinus and throat infections
    • some chest infections (pneumonia)
    • some gastrointestinal infections
    • wound and other skin infections and
    • some types of meningitis.
  • Bacterial infections can occur on their own or can follow a viral infection. If a fever has not gone away within 3 days, it could be that there is a bacterial infection. Your doctor may want to run some tests before ordering antibiotics, such as a urine test or throat swab. Like viral infections, bacterial infections can be mild or can also be serious and life threatening. Seek care if you are feeling worse or not getting better within 72 hours.
• Travel to high-risk areas. If you have travelled to a different region or country and developed a fever, contact a doctor. Infections from other areas can cause fever and may be serious and require specific medicines. These include malaria, tuberculosis, hepatitis A and B and Lyme disease.

Other Causes of Fever

• Blood Clots (serious). These can occur in the legs (deep vein thrombosis) or in the lung (pulmonary embolism) and may happen along with fever. You may have swelling and/or pain in your legs, chest pain or trouble breathing along with the fever.
• Inflammatory Problems. There are many health problems which cause inflammation in the body and a rise in temperature. Examples are rheumatoid arthritis and other joint problems.
• Immune System Problems, such as lupus, can cause fever. If you have a weakened immune system, your body will be less able to defend itself against viral or bacterial infections. Contact your doctor if you get a fever. Examples of a weakened immune system include diabetes, sickle cell disease, HIV, cancer, organ transplant, taking oral steroids, kidney problems.
• Heat Exhaustion. Long exposure to high temps indoors or outdoors can cause a rise in body temperature. It is worse if you're doing strenuous activity and not keeping well hydrated.
• Immunizations. Fever may follow some immunizations such as diphtheria, tetanus, pertussis or pneumococcal vaccine.
• Medicines. Some meds, such as antibiotics and those that treat high blood pressure or seizures, can cause fever.
• Cancer. Some types of malignant cancer can cause fever.

Normal Temperature Range

• Rectal. A reading of 98.6° F (37° C) is just the average rectal temp. A normal low can be 96.8° F (36° C) in the morning. It can change to a high of 100.3° F (37.9° C) late in the day. This is a normal range.
• Oral. A reading of 97.6° F (36.5° C) is just the average mouth temp. A normal low can be 95.8° F (35.5° C) in the morning. It can change to a high of 99.9° F (37.7° C) late in the day. This is a normal range.

When to Call for Fever

Care Advice

What You Should Know about Fever:

• Your body temperature varies through the day and from day to day.
• A fever is a rise in the body temperature above the body's normal range.
• Having a fever is a sign that a change is going on in your body. It is often a new infection and is most likely caused by a virus.
• You may not know the cause of the fever until other symptoms develop. This may take 24 hours or more.
• Most fevers are helpful. They help the body fight infection. Viruses don't survive well if the body is warmer than normal.
• Fevers often go away on their own and don't need treatment.
• You may feel shivery when you have a fever. Shivering causes the body temp to rise. It is a sign the body is fighting the infection. In rare cases, you may find you are shaking. If you have shaking, you should call your doctor.
• Other symptoms that happen with fever include sweating, headache, muscle aches, loss of appetite, feeling irritable, weakness and dehydration.
• Here is some care advice that should help.

Avoiding Infection

• Reducing exposure to infection is the best way to avoid a fever.
• Wash your hands. Do this before eating and after using the toilet. Wash hands after spending time in a crowd, caring for someone who is sick, petting animals, using the toilet and travelling on public transport. Wash hands after coughing, sneezing or blowing your nose. Throw used tissues away.
• Wash hands well for 20 seconds with soap and water and rinse under running water.
• Use hand sanitizer if you don't have access to soap and water.
• Avoid touching your nose, mouth or eyes.
• Cover your mouth when you cough; cover your nose when you sneeze.
• Avoid sharing cups, water bottles and utensils.
• Stay at home when you are sick and avoid close contact with others.
• Avoid close contact with people who are sick, if possible.
• Face masks, if worn, should cover the nose and mouth. They may help reduce spread of infection.
• Avoid hugging and kissing others.
• Wipe down touched surfaces or objects such as doorknobs, kitchen surfaces and mobile devices.

Vaccines:

• Vaccines can prevent infection or reduce how severe a disease is.

Measuring Your Temperature:

• Thermometers vary in accuracy. It is useful to measure your temperature, but the most important thing is how you feel. If you think you have a fever, then assume you do and take action based on how well or ill you are or appear to be.
• There are many types of thermometers: oral (mouth), rectal, ear (tympanic) and forehead. Oral and rectal thermometers are the most accurate.
• If you do measure your temperature, the ranges below may help you interpret your fever:
• 100° - 102° F (37.8° - 39° C) Low grade fever: helpful, good range. Does not need to be treated unless to help you feel better.
• 102° - 104° F (39 - 40° C) Average fever: helpful. Treat if it causes discomfort.
• Over 104° F (40° C) High fever: causes discomfort, but harmless. Always treat.
• Over 106° F (41.1° C) Very high fever: important to bring it down. Rare to go this high.
• Over 108° F (42.3° C) Dangerous fever: fever itself can be harmful.

Treatment for All Fevers - Extra Fluids

• Fluids alone can help lower the temperature and also help you feel better. Reason: you lose fluids through your skin when you have a fever (sweating). This helps reduce the fever, but you could become dehydrated. Drink plenty of fluids to prevent dehydration.

Fever Medicine:

• A fever only needs to be treated with medicine if it is making you feel ill. Most often, that means a fever above 102° F (39° C). Also use for shivering (shaking chills). Shivering will cause the temperature to go higher.
• For fevers higher than 102° F (39° C), take an acetaminophen product (such as Tylenol).
• Another choice is an ibuprofen product (such as Advil).
• Use as needed, but do not take more than the maximum recommended dosage as stated on the package.
• If you are not sure what to take, ask a pharmacist.
• Goal of treatment: bring the temperature down to a level where you feel comfortable. Most often, the fever meds lower the fever by 2° to 3° F (1 - 1.5° C). They do not bring it down to normal. It takes 1 or 2 hours to see the effect.

Sponging with Lukewarm Water:

• Note: sponging is an option for high fevers. It might help you feel better.
• When to Use: fever above 104° F (40° C) that doesn't come down with fever meds. Always give the fever medicine at least an hour to work before sponging.
• How to Sponge: use lukewarm water (85 - 90° F or 29.4 - 32.2° C). Sponge for 20-30 minutes. Using water that is too cold will feel uncomfortable and cause more shivering, making the temperature up higher. The goal is to dampen the skin and the evaporation of the water from the skin will help cool you down.
• If you shiver or becomes cold, stop sponging or make the water warmer.

Other Tips:

• Rest until your fever has come down.
• Avoid strenuous activity.
• If shivering, put on an extra layer of clothes which you can easily remove if you start to overheat.
• In bed, rest under a light sheet rather than a heavy blanket which may send your temperature higher.

Return to Work and Other Activities:

• You can return to work and other activities after the fever is gone for 24 hours.
• You should feel well enough to join in normal activities.

What to Expect:

• Most fevers with viral illnesses range between 101° and 104° F (38.4° and 40° C).
• They may last for 2 or 3 days.
• They are not harmful.

Call Your Doctor If:

• You feel very sick
• Any serious symptoms occur such as trouble breathing
• Fever goes higher than 104° F (40° C)
• Fever with other symptoms lasts more than 3 days (72 hours)
• You think you need to be seen
• Your symptoms get worse

Remember! Contact your doctor if you or your child develop any "Contact Your Doctor" symptoms.

Disclaimer: this health information is for educational purposes only. You, the reader, assume full responsibility for how you choose to use it.




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