What is the recommended dose of diclofenac (Nonsteroidal Anti-Inflammatory Drug (NSAID)) for adults?

Diclofenac Dosing for Adults

For acute pain management in adults, use diclofenac potassium 50 mg three times daily (maximum 150 mg/day), or for severe pain start with 100 mg followed by 50 mg doses, as this formulation provides rapid onset within 30 minutes and superior efficacy compared to diclofenac sodium. 1, 2

Oral Formulations

Diclofenac Potassium (Immediate-Release)

• Acute pain/dysmenorrhea: 50 mg three times daily 1
• Alternative for severe pain: Initial dose of 100 mg, then 50 mg as needed 1
• Maximum daily dose: 150 mg/day 1, 2
• Osteoarthritis: 100-150 mg/day in divided doses (50 mg twice or three times daily) 1
• Rheumatoid arthritis: 150-200 mg/day in divided doses (50 mg three or four times daily) 1

Diclofenac Sodium (Enteric-Coated)

• Less effective for acute pain: This formulation has limited efficacy in acute settings (NNT 6.6 vs 2.1 for potassium salt) and should probably not be used for acute pain 3
• Same dosing range: 100-150 mg/day for chronic conditions if used 4, 5

Low-Dose OTC Formulation

• Diclofenac potassium 12.5 mg tablets: Initial dose of 25 mg (two tablets), then 12.5-25 mg every 4-6 hours, maximum 75 mg/day 2
• Duration limits: Maximum 5 days for pain, 3 days for fever 2

Injectable Formulations

Intravenous Administration

• Standard dose: 75 mg every 12 hours 6, 7
• Maximum daily dose: 150 mg/day (two 75 mg doses) 6
• Minimum interval: 12 hours between doses 6

Intramuscular Administration

• Acute pain/renal colic: 75 mg as single dose 6, 7
• Acute crystal arthritis: 150 mg daily for first 3 days, then 75 mg daily for 3 additional days 6
• Maximum daily dose: 150 mg/day 6

Critical Formulation Differences

Different diclofenac formulations are NOT bioequivalent even at the same milligram strength 1. The potassium salt achieves peak plasma concentration in 30 minutes versus 1.5-2 hours for sodium salt, making it significantly more effective for acute pain 2, 3.

Safety Monitoring and Precautions

Contraindications and High-Risk Situations

• Avoid completely in: Active peptic ulcer disease, severe heart failure, liver failure, history of GI bleeding 6, 7
• Use extreme caution in: History of peptic ulcer, age >60 years, concomitant anticoagulants (bleeding risk increases 3-6 fold), pre-existing cardiovascular disease, renal impairment 8, 6

Monitoring Requirements for Chronic Use

• Baseline and every 3 months: Blood pressure, BUN, creatinine, liver function tests, CBC, fecal occult blood 6
• Discontinue if: BUN or creatinine doubles, liver enzymes increase to 3× upper limit of normal, signs of GI bleeding 6

Dose Adjustments

• Renal impairment: Consider dose reduction if creatinine clearance <10 mL/min 6, 7
• Elderly patients: No routine adjustment needed, but increased monitoring for adverse effects 9

Duration and Treatment Failure

Use the lowest effective dose for the shortest duration 1. If two different NSAIDs fail to provide adequate analgesia, switch to opioid analgesics or non-pharmacologic interventions rather than trialing additional NSAIDs 6.

Common Pitfalls

• Do not use diclofenac sodium for acute pain: The enteric coating delays absorption and reduces efficacy 3
• Do not exceed 150 mg/day by any route: Higher doses significantly increase GI and renal toxicity without additional benefit 8, 6
• Do not combine with anticoagulants without close monitoring: INR increases up to 15% and bleeding risk triples 8
• Do not use COX-1 selective NSAIDs like diclofenac routinely in ICU patients: Small benefits are outweighed by bleeding and kidney injury risks 8