Paracetamol vs Ibuprofen
Clinical Comparison
Clinical Context
Paracetamol and ibuprofen are the two most widely used over-the-counter analgesics. Paracetamol is first-line for simple pain and fever due to its safety profile, while ibuprofen is preferred when inflammation is a significant component. They can be used in combination or alternated for enhanced analgesia.
Drug Profiles
Paracetamol
Non-opioid analgesic / antipyretic
Mechanism
Inhibits central COX enzymes and activates descending serotonergic pain pathways; weak peripheral anti-inflammatory activity
Indications
- Mild to moderate pain
- Pyrexia
- Tension headache
- Post-operative analgesia (step 1 WHO ladder)
Common Doses
500 mg-1 g every 4-6 hours (max 4 g/day in adults)
Route
Oral, IV, rectal
Onset & Duration
Onset 30-60 min oral; duration 4-6 hours
Ibuprofen
NSAID (propionic acid derivative)
Mechanism
Non-selective COX-1 and COX-2 inhibitor, reducing prostaglandin synthesis peripherally and centrally
Indications
- Mild to moderate pain
- Pyrexia
- Inflammatory conditions (arthritis, soft tissue)
- Dysmenorrhoea
- Dental pain
Common Doses
200-400 mg every 6-8 hours (max 2.4 g/day)
Route
Oral, topical gel
Onset & Duration
Onset 20-30 min; duration 6-8 hours
Key Differences
| Category | Paracetamol | Ibuprofen |
|---|---|---|
| Anti-inflammatory effect | Negligible peripheral anti-inflammatory activity | Potent anti-inflammatory — effective for musculoskeletal pain |
| GI safety | No GI ulceration risk | Risk of GI ulceration, bleeding, and dyspepsia |
| Renal effects | Minimal renal impact at therapeutic doses | Can cause acute kidney injury; avoid if eGFR <30 |
| Pregnancy | Safe in all trimesters | Contraindicated in third trimester (premature ductus arteriosus closure) |
| Overdose risk | Hepatotoxicity — potentially fatal; N-acetylcysteine is antidote | GI and renal toxicity; generally better tolerated in overdose |
| Platelet function | No antiplatelet effect | Reversible COX-1 inhibition; mild antiplatelet effect |
Anti-inflammatory effect
Negligible peripheral anti-inflammatory activity
Potent anti-inflammatory — effective for musculoskeletal pain
GI safety
No GI ulceration risk
Risk of GI ulceration, bleeding, and dyspepsia
Renal effects
Minimal renal impact at therapeutic doses
Can cause acute kidney injury; avoid if eGFR <30
Pregnancy
Safe in all trimesters
Contraindicated in third trimester (premature ductus arteriosus closure)
Overdose risk
Hepatotoxicity — potentially fatal; N-acetylcysteine is antidote
GI and renal toxicity; generally better tolerated in overdose
Platelet function
No antiplatelet effect
Reversible COX-1 inhibition; mild antiplatelet effect
Key Advantages
Paracetamol
- Excellent safety profile at therapeutic doses
- Safe in pregnancy (all trimesters)
- No GI ulceration risk
- No antiplatelet effect
Ibuprofen
- Anti-inflammatory action (paracetamol lacks this)
- Effective for musculoskeletal and inflammatory pain
- Available OTC in low doses
- Topical formulation for localised use
Key Cautions
Paracetamol
- Hepatotoxicity in overdose (>150 mg/kg)
- Dose reduction in hepatic impairment and low body weight (<50 kg)
- Maximum 4 g/day in healthy adults; 3 g/day if liver disease
Ibuprofen
- GI ulceration and bleeding risk
- Renal impairment (avoid if eGFR <30)
- Cardiovascular risk with prolonged use
- Avoid in third trimester of pregnancy
- Asthma exacerbation in sensitive patients
Clinical Verdict
Use paracetamol first-line for simple pain and fever. Add or switch to ibuprofen when inflammation is prominent (e.g. sprains, arthritis, dental pain). Avoid ibuprofen in renal impairment, active GI disease, or late pregnancy.
Medical Disclaimer: This comparison is for educational purposes only and is not a substitute for professional medical advice. Always consult a qualified healthcare professional before making prescribing decisions. Verify all drug information with current clinical guidelines (BNF, NICE, SmPCs).
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