What are the recommended doses of paracetamol (acetaminophen), ibuprofen, and other analgesics for treating mild to severe pain?

Recommended Doses of Analgesics for Pain Management

For mild to severe pain management, paracetamol (acetaminophen) should be dosed at 500-1000 mg every 4-6 hours with a maximum daily dose of 4000 mg, while ibuprofen should be dosed at 400 mg every 4-6 hours with a maximum daily dose of 2400 mg. 1, 2

Pain Assessment and Analgesic Selection

Pain intensity should be assessed using standardized tools such as:

• Visual Analog Scale (VAS)
• Numerical Rating Scale (NRS)
• Verbal Rating Scale (VRS)

Pain intensity classification:

• Mild pain: NRS 1-4
• Moderate pain: NRS 5-7
• Severe pain: NRS ≥7

WHO Pain Ladder Approach

Step 1: Mild Pain (NRS 1-4)

• Paracetamol (acetaminophen):

  • Dose: 500-1000 mg every 4-6 hours
  • Maximum daily dose: 4000-6000 mg
  • Onset of action: 15-30 minutes
  • Caution: Hepatotoxicity 1

• NSAIDs:

  • Ibuprofen:

    • Dose: 400 mg every 4-6 hours
    • Maximum daily dose: 2400 mg (4 × 600 mg)
    • Modified release: 800 mg up to 3 times daily (max 2400 mg)
    • Onset of action: 15-30 minutes 1, 2

  • Diclofenac:

    • Dose: 50 mg every 6-8 hours
    • Maximum daily dose: 200 mg (4 × 50 mg)
    • Modified release: 100 mg twice daily
    • Onset of action: 30-120 minutes 1

  • Naproxen:

    • Dose: 250-500 mg every 12 hours
    • Maximum daily dose: 1000 mg (2 × 500 mg)
    • Onset of action: >30 minutes 1

Step 2: Moderate Pain (NRS 5-7)

• Weak opioids combined with non-opioids:

  • Tramadol:

    • Dose: 50-100 mg every 4-6 hours
    • Maximum daily dose: 400 mg
    • Modified release: 100-200 mg every 12 hours 1

  • Dihydrocodeine:

    • Immediate release: 30 mg every 4-6 hours
    • Modified release: 60-120 mg every 12 hours
    • Maximum daily dose: 240 mg 1

  • Combination products (e.g., paracetamol 325 mg + tramadol 37.5 mg):

    • Dose: 1-2 tablets every 4-6 hours
    • Maximum daily dose: 8 tablets 3

Step 3: Severe Pain (NRS ≥7)

• Strong opioids:

  • Morphine:

    • Starting dose: 5-10 mg IV/SC or 20-40 mg oral
    • Titrate based on response
    • No upper limit for dosing 1

  • Oxycodone:

    • Starting dose: 5-10 mg oral
    • Relative potency compared to oral morphine: 2× 1

  • Fentanyl transdermal:

    • Starting dose: 12 μg/h patch
    • For opioid-tolerant patients only
    • Change patch every 72 hours 1

Special Considerations

Breakthrough Pain Management

• Provide "rescue doses" of immediate-release opioids
• Dose should be 10-15% of total daily opioid dose
• If >4 breakthrough doses needed per day, increase baseline opioid dose 1

Managing Side Effects

1. NSAIDs:

   • Caution with: GI toxicity, renal impairment, cardiovascular disease
   • Consider gastric protection for prolonged use 1

2. Opioids:

   • Constipation: Prophylactic laxatives recommended
   • Nausea/vomiting: Antiemetics (metoclopramide, antidopaminergics)
   • Sedation: Consider dose reduction or opioid rotation 1

Special Populations

• Elderly: Consider starting at lower doses, but no routine dose reduction required 4
• Renal impairment: Use caution with NSAIDs and opioids; consider dose reduction 5
• Liver disease: Reduce paracetamol dose in severe liver disease 4
• Children: Paracetamol 10-15 mg/kg every 4-6 hours (max 60 mg/kg/day) 6

Multimodal Analgesia

For optimal pain control, especially in postoperative settings:

• Combine different analgesic classes (e.g., paracetamol + NSAID)
• Consider adjuvant medications (e.g., gabapentinoids, alpha-2-agonists)
• This approach reduces opioid requirements and related side effects 1

Comparative Efficacy

• Ibuprofen 400 mg is superior to paracetamol 1000 mg for pain relief (47% better pain relief at 6 hours) 7
• Paracetamol 1000 mg is more effective than placebo for tension-type headache (NNT = 22 for being pain-free at 2 hours) 8
• Combined paracetamol-ibuprofen formulations may provide better analgesia than either drug alone 7

Remember to use the lowest effective dose for the shortest duration possible to minimize adverse effects while providing adequate pain relief.