Four Seasons Pediatrics

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Fever – When to Worry

Let’s start with a definition of fever:

Your child has a fever if:

  • Rectal, Ear or Forehead temperature: 100.4° F (38.0° C) or higher
  • Oral or Mouth temperature: 100° F (37.8° C) or higher
  • Under the arm (Armpit) temperature: 99° F (37.2° C) or higher
  • Caution: Ear temperatures are not accurate before 6 months of age
  • Caution: Forehead temperatures must be digital. Forehead strips are not accurate.

What are the causes of fever?

  • Main cause: colds and other viral infections.
  • Fever may be the only symptom for the first 24 hours. This often occurs with a viral illness. The start
    of symptoms (runny nose, cough, loose stools) is often delayed. In the case of Roseola, fever may be
    the only symptom for 2 or 3 days.
  • Most often, you won’t know the cause of the fever until other symptoms develop. This may take 24
  • Bacterial infections (as with a Strep throat or a kidney infection) also cause fever.
  • Teething does not cause fever unless a tooth is just breaking the gums
  • Fever and Crying
    • Fever on its own shouldn’t cause much crying.
    • Frequent crying in a child with fever is caused by pain until proven otherwise.
    • Hidden causes can be ear infections, kidney infections, sore throats and meningitis (a very rare cause now a days due to the vaccinations for meningitis)
    • 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.
      • By mouth. 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

What do fevers really mean?

  • Having a fever means your child has a new infection.
  • It’s most likely caused by a virus.
  • Most fevers are good for sick children. They help the body fight infection.
  • Use the ranges below to help put your child’s level of fever into perspective:
    • 100°-102°F (37.8° – 39°C) Slight fever: helpful, good range
    • 102°-104°F (39 – 40°C) Average fever: helpful
    • Above 104°F (40°C) High fever: causes discomfort, but harmless
    • Above 106°F (41.1°C) Very high fever: important to bring it down
    • Above 108°F (42.3°C) Harmful fever: fever itself can be harmful

Treatment for All Fevers – Extra Fluids and Less Clothing:

  • Offer your child lots of cold fluids to drink. Reason: Good hydration replaces sweat. It also
    improves heat loss from the skin.
  • For babies, dress in 1 layer of light weight clothing and sleep with 1 light blanket. Do not wrap in
    too many blankets. This may make the fever higher. Caution: Babies can get over heated easily.
    They can’t take their clothes or blankets off if they are too hot.
  • For fevers 100°-102° F (37.8° – 39°C), fever meds are rarely needed. Fevers of this level don’t
    cause discomfort. They do help the body fight the infection.

Fever Medicine:

  • Fevers only need to be treated with medicine if they cause discomfort. Most often, that means
    fevers above 102°F (39°C). It takes 1 to 2 hours to see the effect.
  • Give acetaminophen (such as Tylenol) or ibuprofen (such as Advil). See the Dose Tables.
  • Goal of treatment: Bring the temperature down to a comfortable level. Most often, the fever
    meds only lower the fever by 2° to 3° F (1 – 1.5° C). They do not bring it down to normal.
  • Do not use aspirin. Reason: Risk of Reye syndrome, a rare but serious brain disease.
  • Most children do not need to take both acetaminophen and ibuprofen together.


  • Note: Sponging is an option for high fevers, but not required.
  • When to Use: Fever above 104° F (40° C) AND doesn’t come down with fever meds. Always give
    the fever med first.
  • How to Sponge: Use lukewarm water (85 – 90° F) (29.4 – 32.2° C). Sponge for 20-30 minutes.
    • If your child shivers or becomes cold, stop sponging. Other option: You can also make the water
  • Caution: Do not use rubbing alcohol. Reason: Can cause a coma.

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.

Return to School:

  • Your child can return to school after the fever is gone for 24 hours
  • Your child should feel well enough to join in normal activities.

When to call us for a fever:

  • Your child looks or acts very sick
  • Any serious symptoms occur like trouble breathing
  • Any fever occurs if under 12 weeks old
  • Fever without other symptoms lasts over 24 hours (if age less than 2 years)
  • Fever lasts over 3 days (72 hours)
  • Fever goes above 105 F (40.6 C) – this is rare
  • Your child becomes worse

Please note: for dosing of acetaminophen or ibuprofen – visit our website at or Click Here

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