What alternative antipyretic can be given to a febrile adult or pediatric patient with a known allergy to paracetamol (acetaminophen)?

Alternative Antipyretic for Paracetamol-Allergic Patients

Ibuprofen is the recommended alternative antipyretic for febrile patients with paracetamol allergy, with standard dosing of 7-10 mg/kg every 6-8 hours in children and 400-600 mg every 6-8 hours in adults. 1, 2, 3

Primary Alternative: Ibuprofen

Efficacy Evidence

• Ibuprofen has been shown to be at least as effective as paracetamol as an analgesic and more effective as an antipyretic in comparative trials 4
• Multiple randomized controlled trials demonstrate that ibuprofen provides greater temperature reduction and longer duration of antipyresis than acetaminophen when administered in approximately equal doses 3
• The mean fall in temperature is comparable between ibuprofen (7 mg/kg) and paracetamol (8 mg/kg) at 1.5, and 2 hours, with no statistically significant differences 2

Practical Advantages

• Ibuprofen requires less frequent dosing (every 6-8 hours) compared to paracetamol (every 4 hours), making it more convenient for patients and caregivers 4
• The longer duration of action makes it particularly suitable as a paracetamol alternative 4

Dosing Recommendations

• Pediatric patients: 7-10 mg/kg every 6-8 hours 1, 2, 3
• Adult patients: Standard NSAID dosing applies (typically 400-600 mg every 6-8 hours)
• Ibuprofen should be considered second-line antipyretic therapy when first-line agents cannot be used 5

Important Safety Considerations and Contraindications

High-Risk Populations Requiring Caution

• Patients older than 60 years or with compromised fluid status or renal insufficiency should receive ibuprofen with extreme caution due to risks of gastrotoxicity, respiratory failure, metabolic acidosis, and renal failure 1
• Avoid ibuprofen in patients with active gastrointestinal bleeding, severe renal impairment, or cardiovascular disease where NSAID risks outweigh benefits 1
• In COVID-19 patients with severe disease involving kidney, cardiac, or gastrointestinal injury, NSAIDs should be stopped 6

Pediatric-Specific Warnings

• Aspirin must be avoided in children under 16 years due to Reye's syndrome risk, particularly with viral illnesses 1, 5
• Ibuprofen carries risks of respiratory failure, metabolic acidosis, and renal failure in overdose or in the presence of risk factors 1

Overdose Safety Profile

• In overdose situations, ibuprofen toxicity is reached much later, is less severe, and is easier to manage compared to paracetamol overdose 4
• This represents a significant safety advantage when paracetamol cannot be used 4

Adjunctive Non-Pharmacologic Measures

Supportive Care

• Encourage adequate fluid intake, which is crucial for patient well-being during febrile illness 1
• Maintain appropriate environmental temperature and reduce excessive covering during warmer months 6
• Avoid physical cooling methods (tepid sponging, fanning) as they cause discomfort without improving outcomes 6

Special Clinical Contexts

• In stroke patients with fever, early treatment with antipyretics (including ibuprofen as alternative) may be considered for comfort, though evidence for improved neurological outcomes is limited 7, 6
• Antipyretics do not prevent febrile seizures or reduce their recurrence risk in children, so this should not be the primary rationale for treatment 1, 6

Clinical Algorithm for Implementation

1. Confirm true paracetamol allergy (vs. intolerance or previous adverse event from other causes)
2. Screen for ibuprofen contraindications: renal disease, GI bleeding history, severe dehydration, age >60 with risk factors 1
3. If ibuprofen is contraindicated, consider non-pharmacologic comfort measures only, as other antipyretics (aspirin) carry unacceptable risks in most populations 1, 5
4. Administer ibuprofen at appropriate weight-based or standard dosing 2, 3
5. Monitor for adequate hydration and antipyretic response 1
6. Identify and treat the underlying source of fever, as this is more important than temperature reduction alone 7, 6