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Fever (0-12 Months)

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Definition

  • An abnormal high body temperature
  • Fever is the only symptom. Your child has a true fever if:
  • Rectal (bottom), Ear or Forehead temperature: 100.4° F (38.0° 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.

Causes of Fever

  • Overview. Almost all 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.
  • 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 viral symptoms (runny nose, cough, loose stools) is often delayed. Roseola is the most extreme example. Fever may be the only symptom for 2 or 3 days. Then a rash appears.
  • Bacterial Infections. A bladder infection is the most common cause of silent fever in girls. Strep throat is also a common cause of unexplained fever.
  • Vaccine Fever. Fever with most vaccines begins within 12 hours. It lasts 2 to 3 days. This is normal and harmless. It means the vaccine is working.
  • Newborn Fever (Serious). Fever that occurs during the first 3 months of life can be serious. All of these babies need to be seen as soon as possible. The fever may be due to sepsis (a bloodstream infection). Bacterial infections in this age group can get worse quickly. They need rapid treatment.
  • Meningitis (Very Serious). A bacterial infection of the membrane that covers the spinal cord and brain. The main symptoms are a stiff neck, headache and confusion. Younger children are lethargic or so irritable that they can't be consoled. If not treated early, can suffer brain damage.
  • Overheated. The fever is usually low grade. Can occur during heat waves or from being overdressed. The temp becomes normal in a few hours after moving to a cooler place. Fever goes away quickly with rest and drinking extra fluids.
  • Not Due to Teething. Research shows that "getting teeth" does not cause fevers.

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.

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.
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When To Call

Call 911 Now

  • Not moving
  • Can't wake up
  • Severe trouble breathing (struggling for each breath; can barely speak or cry)
  • Purple or blood-colored spots or dots on skin
  • You think your child has a life-threatening emergency

Go to ER Now

  • Stiff neck
  • Soft spot on top of head looks swollen
  • Hard to wake up
  • Had a seizure with the fever
  • Not alert when awake ("out of it")

Call Doctor or Seek Care Now

  • Trouble breathing, but not severe
  • Great trouble swallowing fluids or spit
  • Fever in baby less than 12 weeks old. Caution: Do NOT give your baby any fever medicine before being seen.
  • Fever over 104° F (40° C)
  • Shaking chills (shivering) lasting more than 30 minutes
  • Nonstop crying or cries when touched or moved
  • Won't move an arm or leg normally
  • Dehydration suspected. No urine in over 8 hours, dark urine, very dry mouth and no tears.
  • Weak immune system. Examples are sickle cell disease, HIV, cancer, organ transplant, taking oral steroids.
  • Your child looks or acts very sick
  • You think your child needs to be seen, and the problem is urgent

Contact Doctor Within 24 Hours

  • Age 3-6 months old with fever
  • Age 6-12 months old with fever that lasts more than 24 hours. There are no other symptoms (such as cough or diarrhea).
  • Fever lasts more than 3 days
  • Fever returns after gone for more than 24 hours
  • You think your child needs to be seen, but the problem is not urgent

Contact Doctor During Office Hours

  • You have other questions or concerns

Self Care at Home

  • Fever with no other symptoms and your child acts mildly ill
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Care Advice

  1. What You Should Know About Fever:
    • Having a fever means your child has a new infection.
    • It's most likely caused by a virus.
    • You may not know the cause of the fever until other symptoms develop. This may take 24 hours.
    • For infants more than 3 months old, 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) Low grade fever: helpful, good range. Don't treat.
    • 102° - 104° F (39 - 40° C) Average fever: helpful. Treat if 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.
  2. Treatment for All Fevers - Extra Fluids:
    • Fluids alone can lower the fever. Reason: being well hydrated helps the body give off heat through the skin.
    • Offer your child extra water or other fluids by mouth. Cold fluids are better. Until 6 months old, only give extra formula or breastmilk.
    • For all children, dress in 1 layer of light weight clothing, unless shivering. Reason: also helps heat loss from the skin.
    • Caution: if a baby under 1 year has a fever, never overdress or bundle up. Reason: Babies can get over-heated more easily than older children.
    • 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.
    • Exception: if you feel your child also has pain, treat it.
  3. Fever Medicine:
    • Caution: Do not give a baby under 3 months any fever medicine. Most of these babies will need to be seen.
    • Fevers only need to be treated with medicine if they cause discomfort. Most often, that means fevers above 102° F (39° C). Also use for shivering (shaking chills). Shivering means the fever is going up.
    • For fevers above 102° F (39° C), give an acetaminophen product (such as Tylenol).
    • Another choice is an ibuprofen product (such as Advil) if over 6 months old.
    • Goal of treatment: Bring the temperature down to a comfortable level. 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.
    • Do not use aspirin. Reason: Risk of Reye syndrome, a rare but serious brain disease.
    • Do not use both acetaminophen and ibuprofen together. Reason: Not needed and a risk of giving too much.
  4. Return to Child Care:
    • Your child can return to child care after the fever is gone. Your child should feel well enough to join in normal activities.
  5. 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.
  6. Call Your Doctor If:
    • Your child looks or acts very sick
    • Any serious symptoms occur such as trouble breathing
    • Fever goes above 104° F (40° C)
    • Any fever occurs if less than 12 weeks old
    • Fever without other symptoms lasts more than 24 hours
    • Fever lasts more than 3 days (72 hours)
    • You think your child needs to be seen
    • Your child becomes worse

And remember, contact your doctor if your child develops any of the 'Call Your Doctor' symptoms.

Barton Schmitt MD, FAAP
Disclaimer: this health information is for educational purposes only. You, the reader, assume full responsibility for how you choose to use it.
Copyright 2000-2021 Schmitt Pediatric Guidelines LLC.
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