What is the best analgesic for pain management?

Best Analgesic for Pain Management

For mild to moderate pain, acetaminophen (paracetamol) 1000 mg every 4-6 hours is the recommended first-line analgesic, with ibuprofen 400 mg every 4-6 hours as the preferred NSAID if additional analgesia is needed. 1

Mild to Moderate Pain (Pain Score 1-4)

First-Line Treatment

• Start with acetaminophen 1000 mg every 4-6 hours (maximum 4000 mg/day), as it provides effective analgesia with the most favorable safety profile compared to NSAIDs 1, 2
• Acetaminophen is particularly suitable for patients with cardiovascular disease, kidney disease, gastrointestinal disorders, bleeding risk, or older adults 3

Second-Line: Add or Switch to NSAIDs

• If acetaminophen alone is insufficient, add ibuprofen 400 mg every 4-6 hours (maximum 2400 mg/day) 1, 4, 2
• Ibuprofen 400 mg is the safest NSAID choice with the best evidence for efficacy; higher doses (600-800 mg) offer minimal additional benefit but increase adverse effects 4, 2
• Always prescribe a proton pump inhibitor with NSAIDs for gastric protection when used beyond short-term 1
• NSAIDs are particularly effective for inflammatory pain and bone pain 1

Critical NSAID Contraindications

• Do not use NSAIDs in patients with: renal impairment, heart failure, history of gastrointestinal bleeding, concurrent methotrexate use, or those receiving nephrotoxic/myelotoxic chemotherapy 1

Moderate Pain (Pain Score 5-7)

Combination Therapy

• Combine acetaminophen 1000 mg every 4-6 hours with ibuprofen 400 mg every 4-6 hours 1
• If inadequate, add a weak opioid: codeine 30-60 mg, tramadol 50-100 mg, or dihydrocodeine 60-120 mg every 4-6 hours 1
• Alternative approach: Start low-dose strong opioids (morphine 10-20 mg orally) instead of weak opioids, as this may be more effective 1

Important Limitation

• Research shows acetaminophen has limited efficacy for chronic pain conditions, though it remains effective for acute pain 5
• Codeine has poor efficacy and should not be considered a preferred weak opioid 2

Severe Pain (Pain Score 8-10)

Immediate Strong Opioid Initiation

• Start oral morphine 20-40 mg immediately for opioid-naïve patients 1, 6
• If oral route unavailable or urgent relief needed: morphine 5-10 mg IV or SC 1, 6
• Continue acetaminophen 1000 mg every 4-6 hours and ibuprofen 400 mg every 4-6 hours (if no contraindications) as multimodal analgesia 6

Alternative Strong Opioids

• Oxycodone 20 mg orally (1.5-2x more potent than morphine) 1, 6
• Hydromorphone 8 mg orally (7.5x more potent than morphine) 1, 6
• For renal impairment (eGFR <30 mL/min): Use fentanyl or buprenorphine IV/transdermal 1, 6

Dosing Principles for Severe Pain

• Administer opioids on a regular schedule (every 4 hours for immediate-release morphine), not "as needed" 1, 6
• Prescribe rescue doses of 10-15% of total daily opioid dose as immediate-release formulation for breakthrough pain 1, 6
• If more than 4 breakthrough doses needed per day, increase the baseline scheduled opioid dose 1
• Oral to IV/SC morphine conversion ratio is 1:2 to 1:3 1, 6

Mandatory Prophylaxis

• Prescribe laxatives routinely for all patients on opioids 1, 6
• Prescribe antiemetics (metoclopramide or antidopaminergics) for opioid-induced nausea/vomiting 1, 6

Neuropathic Pain Component

Coanalgesics (Add to Opioids)

• First-line: Gabapentin starting 100-300 mg nightly, titrate to 900-3600 mg daily in divided doses 1
• Alternative: Pregabalin starting 50 mg three times daily, titrate to 100 mg three times daily (maximum 600 mg/day) 1
• Tricyclic antidepressants: Nortriptyline or desipramine 10-25 mg nightly, titrate to 50-150 mg nightly (better tolerated than amitriptyline) 1
• Duloxetine 30-60 mg daily, titrate to 60-120 mg daily 1

Critical Pitfalls to Avoid

• Never delay strong opioids for severe pain—the WHO ladder allows starting at step 3 for very severe pain 1, 6
• Never prescribe two sustained-release opioids together 1
• Never use transdermal fentanyl for initial pain control or rapid titration—reserve for stable pain controlled with other opioids (≥60 mg/day morphine equivalent) 1
• Never exceed acetaminophen 4000 mg/day due to hepatotoxicity risk 1
• Never combine NSAIDs with methotrexate 1
• Avoid codeine, propoxyphene, and tramadol as they show poor efficacy and significant side effects 2