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

Diclofenac Dosing for Adults

For oral diclofenac, use 50 mg three times daily for acute pain or primary dysmenorrhea, or 100-150 mg/day in divided doses for osteoarthritis, with a maximum daily dose of 150-200 mg depending on indication. 1

Oral Formulations

Immediate-Release Diclofenac Potassium

Standard dosing regimens:

• Acute pain/primary dysmenorrhea: 50 mg three times daily is the standard dose 1
• Alternative acute pain regimen: Initial dose of 100 mg, followed by 50 mg doses may provide better relief in some patients 1
• 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

Low-dose OTC formulation (12.5 mg tablets):

• Initial dose of 2 tablets (25 mg), followed by 1-2 tablets every 4-6 hours as needed 2
• Maximum daily dose: 6 tablets (75 mg/day) 2
• Maximum treatment duration: 5 days for pain, 3 days for fever 2

Important Formulation Note

Different diclofenac formulations (sodium enteric-coated, sodium extended-release, potassium immediate-release) are not bioequivalent even at the same milligram strength 1. Do not substitute formulations without adjusting dosing.

Injectable Diclofenac

Intramuscular Administration (Preferred Route)

Intramuscular injection is the preferred route for injectable diclofenac over intravenous administration in most clinical settings. 3

Standard IM dosing:

• Acute pain: 75 mg as a single dose 3
• Acute renal colic: 75 mg IM as first-line treatment 3, 4
• Acute crystal-induced arthritis: 150 mg daily for first 3 days, then 75 mg daily for 3 additional days 3

Intravenous Administration

Maximum daily dose by any parenteral route is 150 mg, administered as 75 mg every 12 hours. 3

• IV administration should be reserved for severe cases not responding to IM diclofenac or hospital settings with appropriate monitoring 3
• IV carries significant risks of dilution and dosing errors 3
• For postoperative pain: 18.75-37.5 mg IV boluses every 6 hours 3

Critical safety limit: Never exceed 150 mg/day by any route, as higher doses significantly increase gastrointestinal and renal toxicity without additional benefit 3

Dosing by Clinical Indication

Kidney Stone Pain (Renal Colic)

• Oral: 50 mg three times daily 4
• IV: 75 mg every 12 hours (maximum 150 mg/day) 4
• NSAIDs are first-line treatment, reducing need for additional analgesia compared to opioids 4

Influenza-Like Symptoms

• Initial dose: 2 tablets of 12.5 mg (25 mg total) 5
• Maintenance: 1-2 tablets every 4-6 hours as needed 5
• Maximum: 75 mg/day for up to 3 days for fever, 5 days for pain 5

Critical Safety Considerations

Absolute Contraindications

Avoid diclofenac completely in patients with: 3

• Active peptic ulcer disease
• Severe heart failure
• Liver failure
• History of gastrointestinal bleeding

High-Risk Situations Requiring Extreme Caution

Use with extreme caution or avoid in: 3

• History of peptic ulcer disease
• Age >60 years
• Concomitant anticoagulant use (increases bleeding risk 3-6 fold) 3
• Pre-existing cardiovascular disease
• Renal impairment (consider dose reduction if creatinine clearance <10 mL/min) 3
• Compromised fluid status or concurrent nephrotoxic drugs

Monitoring Requirements for Chronic Use

For patients on chronic NSAID therapy, monitor every 3 months: 3

• Blood pressure
• BUN and creatinine
• Liver function tests
• Complete blood count
• Fecal occult blood

Discontinuation criteria: 3

• BUN or creatinine doubles
• Liver function tests increase to 3× upper limit of normal
• Development of gastrointestinal bleeding
• Worsening hypertension

Clinical Pearls

Common pitfall: Do not combine diclofenac with anticoagulants without close monitoring, as INR can increase up to 15% and bleeding risk triples 3. If two NSAIDs fail sequentially, switch to alternative analgesic approaches (opioids, nerve blocks) rather than trialing additional NSAIDs 3.

Duration of action: Despite a short plasma half-life of 1.5 hours, diclofenac persists in synovial fluid, providing 6.7-7.2 hours of analgesia with 50-100 mg doses 6, 7.