What is the difference between Meftal (Mefenamic acid) and Paracetamol (Acetaminophen) for pain and fever relief?

Mefthal vs Paracetamol: Clinical Comparison

For mild to moderate pain and fever, paracetamol should be your first-line choice due to its superior safety profile, while mefenamic acid (Mefthal) should be reserved specifically for pain with inflammatory components or when paracetamol proves inadequate. 1

Primary Recommendation Framework

First-Line: Paracetamol

• Paracetamol is recommended as first-line therapy by international guidelines (EULAR, ACR) for pain and fever management 1
• Standard dosing: 1000mg every 6 hours, maximum 4g/24 hours 2, 3
• Effective for headache, muscular aches, backache, arthritis pain, common cold, toothache, and menstrual cramps 3
• Paracetamol has significantly fewer adverse events compared to NSAIDs like mefenamic acid, particularly regarding gastrointestinal, cardiovascular, and renal complications 1

Second-Line: Mefenamic Acid (Mefthal)

• Reserve for pain with inflammatory components or when paracetamol fails 1
• Mefenamic acid is an NSAID with anti-inflammatory properties that paracetamol lacks 4
• Should not be used as routine antipyretic due to NSAID-associated risks 5

Efficacy Comparison

Pain Relief

• Both agents demonstrate similar antipyretic efficacy when paracetamol is used at higher doses (20mg/kg in children, equivalent to ~1000mg in adults) 5
• High-dose paracetamol (20mg/kg) achieved temperature normalization in 85 minutes versus 85 minutes for mefenamic acid—no significant difference 5
• Paracetamol is comparable to ibuprofen for short-term pain relief and nearly as efficacious as naproxen for chronic conditions 1

Duration of Action

• Mefenamic acid may provide slightly longer duration (8.8 hours to next fever) compared to high-dose paracetamol (7.2 hours), though this difference was not statistically significant 5
• Standard-dose paracetamol (15mg/kg) had shorter duration (5.1 hours) 5

Safety Profile: Critical Differences

Paracetamol Safety

• Minimal gastrointestinal toxicity at recommended doses 1
• No significant cardiovascular or renal effects with short-term use (<14 days) 6
• Safe in older adults, liver disease (when used appropriately), kidney disease, cardiovascular disease, and asthma 1, 6
• Hepatotoxicity only occurs with overdose (>4g/day chronically or acute massive ingestion) 1, 6

Mefenamic Acid (NSAID) Risks

• Dose-dependent gastrointestinal bleeding risk: relative rate increases from 1.11 to 1.49 with higher doses 1
• Cardiovascular adverse events show dose-response: risk ratio increases from 1.19 to 1.68 1
• Renal adverse events with dose-response: OR of ≥30% decrease in kidney function increases from 1.40 to 2.19 1
• Contraindicated in patients with history of GI bleeding, renal impairment, heart failure, or cardiovascular disease 2

Clinical Decision Algorithm

Step 1: Initial Assessment

• Start with paracetamol 1000mg every 6 hours (maximum 4g/24 hours) 2, 3
• Assess for contraindications: severe liver disease, chronic alcohol use, or known paracetamol allergy 6

Step 2: Evaluate Response After 1-2 Doses

• If adequate pain/fever relief: continue paracetamol alone 2
• If inadequate relief: verify patient is taking full 1000mg doses before escalating 1

Step 3: Consider Mefenamic Acid Only If:

• Pain has clear inflammatory component (arthritis, dysmenorrhea, inflammatory conditions) 1
• Patient has no GI, cardiovascular, or renal contraindications 2
• Paracetamol at maximum dose has failed 1
• Use lowest effective dose for shortest duration 7, 2

Step 4: High-Risk Patients

• Older adults: use paracetamol preferentially; no routine dose reduction needed 1, 6
• Cardiovascular disease: paracetamol is preferred first-line 2, 6
• Renal impairment: avoid NSAIDs; paracetamol is safer 2, 6
• GI bleeding history: absolutely avoid mefenamic acid 2

Common Pitfalls to Avoid

Paracetamol Misuse

• Patients often take subtherapeutic doses (<1000mg); ensure full dosing before declaring failure 1
• Monitor total daily paracetamol from all sources (combination products, OTC medications)—maximum 4g/24 hours 1, 3
• Do not routinely reduce dose in elderly without specific indication 6

Inappropriate NSAID Use

• Do not use mefenamic acid as routine antipyretic—this exposes patients to unnecessary NSAID risks 5
• Chronic NSAID use (including mefenamic acid) shows dose-dependent mortality increase: relative rate up to 1.63 1
• Avoid in patients taking anticoagulants, corticosteroids, or other NSAIDs 2

Special Populations

Older Adults

• Paracetamol remains first-line with standard dosing 1, 6
• NSAIDs carry disproportionately higher risk in elderly due to age-related renal decline and cardiovascular comorbidities 1

Chronic Pain Conditions

• Paracetamol can be used safely long-term (up to 2 years studied) when indicated 1
• Long-term NSAID use shows significantly more adverse events than paracetamol 1, 8

Liver Disease

• Paracetamol is safe at standard doses even in compensated cirrhosis 6
• Decompensated cirrhosis requires individualized dosing in consultation with hepatologist 6