From the Guidelines
A fever is generally defined as a body temperature above 38°C (100.4°F) in both children and adults, though the threshold may vary slightly depending on measurement method. For adults, a temperature between 38-39°C is considered a mild fever, while anything above 39°C is a high fever. In children, fever thresholds are similar, but interpretation differs by age. For infants under 3 months, any fever (≥38°C) warrants immediate medical attention due to their immature immune systems, as stated in the clinical policy for well-appearing infants and children younger than 2 years of age presenting to the emergency department with fever 1. For children 3 months to 3 years, temperatures up to 39°C may be monitored at home if the child appears well otherwise, while temperatures above 39°C often require medical evaluation.
Key Considerations
- Fever itself is not dangerous but rather a natural immune response; treatment focuses on comfort rather than normalizing temperature.
- Very high fevers (above 40°C/104°F) or fevers accompanied by concerning symptoms like lethargy, breathing difficulty, or persistent vomiting require prompt medical evaluation.
- The risk of serious bacterial infections (SBI) in febrile infants and children has been reported as 13% in neonates (aged 3 to 28 days), 9% in infants aged 29 to 56 days, and 7% in infants aged 90 days or younger, according to the study published in the Annals of Emergency Medicine 1.
Management
- Fever can be managed with acetaminophen (10-15 mg/kg every 4-6 hours, maximum 5 doses/day) or ibuprofen (5-10 mg/kg every 6-8 hours) for children over 6 months.
- For adults, standard doses are acetaminophen 500-1000 mg every 4-6 hours (maximum 4000 mg/day) or ibuprofen 200-400 mg every 4-6 hours.
- The evaluation and management of the febrile child is evolving, and the introduction of vaccines such as Haemophilus influenzae type b (HIB) and Streptococcus pneumoniae has likely decreased the incidence of serious bacterial infections, as mentioned in the clinical policy for children younger than three years presenting to the emergency department with fever 2.
Clinical Predictors
- For well-appearing immunocompetent infants and children aged 2 months to 2 years presenting with fever (≥ 38.0 C [100.4 F]), clinical predictors can identify patients at risk for urinary tract infection, as discussed in the clinical policy for well-appearing infants and children younger than 2 years of age presenting to the emergency department with fever 3.
- The use of laboratory testing methods, such as urine testing, can help diagnose urinary tract infections in febrile infants and children.
From the Research
Fever Temperature in Children and Adults
- The normal body temperature for adults and children is around 98.6°F (37°C), but it can vary slightly from person to person 4.
- Fever is a common symptom of illness, and its management is crucial in both children and adults.
Fever Management in Children
- Studies have shown that both acetaminophen and ibuprofen are effective in reducing fever in children 5, 6, 7, 8.
- A systematic review and meta-analysis found that combined or alternating therapy with acetaminophen and ibuprofen may be more effective in reducing fever than monotherapy alone 5, 7.
- Another study found that ibuprofen was marginally more effective than acetaminophen in reducing fever, but the maximum dose of paracetamol was not administered 6.
- A network meta-analysis found that combined and alternating therapies may be superior to acetaminophen, while ibuprofen at a high dose may be comparable in terms of proportion of afebrile children at the fourth hour 7.
Comparison of Acetaminophen and Ibuprofen
- A systematic review and meta-analysis found that ibuprofen resulted in reduced temperature and less pain compared to acetaminophen in children younger than 2 years 8.
- Another study found that acetaminophen and ibuprofen had similar serious adverse event profiles, with uncommon adverse events reported 8.
- The American Academy of Pediatrics recommends the use of acetaminophen or ibuprofen for fever reduction in children, with the choice of medication depending on the individual child's needs and medical history 4.
Fever Temperature Ranges
- Mild fever: 100.4°F (38°C) to 102.2°F (39°C) 4.
- Moderate fever: 102.2°F (39°C) to 104°F (40°C) 4.
- High fever: above 104°F (40°C) 4.
- It is essential to note that fever temperature ranges can vary depending on the age and medical condition of the individual, and it is crucial to consult a healthcare professional for proper evaluation and treatment.