From the Research
After giving Tylenol (acetaminophen) to an infant with fever, temperature typically begins to decrease within 30-60 minutes, with maximum effect occurring around 2-3 hours after administration, resulting in a mean maximum decrease of 1.4-1.5 degrees C in body temperature at 3 hours compared to baseline 1. The fever reduction varies between children, but generally ranges from 1-2°F (0.5-1°C). Some key points to consider:
- The standard dosage for infants is 10-15 mg per kilogram of body weight every 4-6 hours as needed, not exceeding 5 doses in 24 hours.
- Always use the measuring device provided with the medication for accurate dosing based on your child's weight, not age.
- Tylenol works by affecting the hypothalamus in the brain, which regulates body temperature, and by inhibiting prostaglandin production that causes fever.
- While reducing fever, remember that Tylenol treats the symptom but not the underlying cause of illness.
- Contact a doctor if the fever persists beyond 3 days, exceeds 102°F (38.9°C) in infants under 3 months, or if your infant shows signs of dehydration, unusual irritability, or lethargy. Recent studies have compared the efficacy of acetaminophen with ibuprofen for the treatment of fever in children, with one study finding that ibuprofen resulted in reduced temperature at less than 4 hours and at 4 to 24 hours compared to acetaminophen 2. Another study found that combined paracetamol and ibuprofen therapy can result in a lower mean temperature at one hour after treatment and at four hours after treatment compared to monotherapy 3. A network meta-analysis found that combined and alternating therapies may be superior to acetaminophen alone in terms of proportion of afebrile children at the fourth hour 4.