How Long Does Motrin Take to Work for Fever?
Motrin (ibuprofen) typically begins reducing fever within 1.5 to 2.5 hours after administration, with maximum fever reduction occurring around 4 hours post-dose. 1
Onset of Antipyretic Effect
Ibuprofen demonstrates superior fever-reducing efficacy compared to acetaminophen (paracetamol), particularly in pediatric populations, with statistically significant differences in the proportion of afebrile children appearing between 1.5 to 2.5 hours after a single dose. 1
In hospitalized adult patients with fever, ibuprofen (400 mg dose) achieved temperature reduction to <38.3°C within 4 hours of the first dose in significantly more patients compared to placebo. 2
Meta-analysis data confirms that ibuprofen provides significant fever reduction at 4 hours post-dose in pediatric patients (standardized mean difference 0.26; 95% CI 0.10 to 0.41), demonstrating consistent antipyretic efficacy. 3
Dosing Considerations for Optimal Effect
The recommended dose is 10 mg/kg for children (maximum 3 doses in 24 hours, given every 6-8 hours) and 400-800 mg for adults (maximum 4 doses in 24 hours). 4, 2
For persistent fever, ibuprofen can be administered at 0.2 g (200 mg) per dose every 4-6 hours as needed, not exceeding 4 doses in 24 hours. 5
Weight-based dosing (10 mg/kg per dose for children, 15 mg/kg for acetaminophen) ensures optimal therapeutic effect while minimizing risk of exceeding maximum recommended doses. 4
Comparative Effectiveness
Ibuprofen provides superior antipyretic efficacy compared to acetaminophen, particularly for bacterial infections, and is recommended as first-line therapy for fever management. 6
When comparing monotherapy options, children treated with ibuprofen first may experience faster fever resolution than those given acetaminophen, though both medicines together provide approximately 2.5 additional hours without fever over 24 hours compared to ibuprofen alone. 4
Important Clinical Caveats
In patients taking aspirin for cardiovascular protection, ibuprofen should be taken at least 30 minutes after immediate-release aspirin or at least 8 hours before aspirin to avoid interfering with aspirin's antiplatelet effects. 7
Ibuprofen and other NSAIDs should be avoided in patients with established COVID-19 infection when alternatives exist, based on the precautionary principle, though no scientific evidence links NSAID use to worsening COVID-19 severity. 5
For patients with chronic alcohol use or liver disease, extreme caution should be exercised with any antipyretic use, including ibuprofen. 6
Renal function and blood pressure should be monitored in patients taking ibuprofen, especially those with preexisting hypertension, renal disease, or heart failure, as NSAIDs can cause fluid retention and blood pressure increases. 7
Parents should carefully record all dose times when using ibuprofen to avoid accidentally exceeding the maximum recommended dose, as 11% of children in clinical trials exceeded the recommended maximum number of doses. 4