What is the recommended dose of intramuscular (IM) diclofenac (nonsteroidal anti-inflammatory drug (NSAID)) in pregnant women?

Diclofenac Should Not Be Used During Pregnancy—No Specific "Dose" Is Recommended

Injectable diclofenac is not recommended during pregnancy, and there is no established safe dose for intramuscular administration in pregnant women. The focus should be on avoiding NSAIDs entirely or using them only when absolutely necessary with strict gestational age restrictions, not on finding an appropriate dose.

Critical Gestational Age-Based Restrictions

First Trimester (Weeks 0-13)

• Diclofenac can be used only if clinically essential, with the understanding that early exposure shows no increased risk of miscarriage or teratogenicity 1
• Use the lowest effective dose for the shortest possible duration (maximum 7-10 days) 1, 2
• Most reassuring safety data exist for ibuprofen, followed by diclofenac, making ibuprofen the preferred NSAID if one must be used 1
• Women actively trying to conceive should discontinue all NSAIDs due to risk of luteinized unruptured follicle syndrome causing subfertility 1, 2

Second Trimester (Weeks 14-28)

• Short-term use (7-10 days maximum) is acceptable only until week 28 1, 2
• Avoid use after week 20 if possible due to emerging fetal renal risks 2
• High-dose diclofenac (≥150 mg/day) has been associated with early-onset oligohydramnios even before week 28 3

After Week 28 (Third Trimester)

• Absolute contraindication—diclofenac must be discontinued 1
• Risk of premature ductus arteriosus closure, oligohydramnios, and fetal kidney damage 1, 3, 4, 5

Preferred Alternatives to Injectable Diclofenac

First-Line Analgesic

• Acetaminophen is the preferred analgesic across all trimesters at the lowest effective dose for the shortest duration 2, 6

If NSAID Required in First/Second Trimester

• Oral ibuprofen 200-400 mg every 6-8 hours is preferred over diclofenac, limited to 7-10 days maximum 2, 6
• Ibuprofen has more reassuring safety data than diclofenac 1, 6

For Chronic Inflammatory Conditions

• Transition to pregnancy-compatible alternatives before conception:
  • Hydroxychloroquine 1
  • Sulfasalazine (up to 2 g/day with folic acid supplementation) 1
  • Low-dose prednisone (≤10 mg/day) 1
  • Azathioprine (up to 2 mg/kg/day) 1

Critical Pitfalls to Avoid

• Do not prescribe injectable diclofenac as routine analgesia in pregnancy—the parenteral route offers no safety advantage and may lead to higher systemic exposure 4
• The traditional "third trimester" designation is misleading—the critical cutoff is week 28, not week 27 or later 2, 6
• High-dose or prolonged NSAID use before week 28 is not safe—oligohydramnios has been documented as early as weeks 22-23 with diclofenac ≥150 mg/day 3
• Never assume NSAIDs are safe for fertility—discontinue in women actively trying to conceive 1, 2

Clinical Decision Algorithm

1. Is the patient pregnant or planning pregnancy?

   • If planning: Discontinue all NSAIDs; transition to pregnancy-compatible alternatives 1, 2

2. What is the gestational age?

   • <28 weeks: Consider acetaminophen first; if insufficient, oral ibuprofen (not diclofenac) for ≤7-10 days 2, 6
   • ≥28 weeks: Absolute contraindication to all NSAIDs 1

3. Is this acute pain or chronic inflammatory disease?

   • Acute: Acetaminophen or short-term oral ibuprofen (first/second trimester only) 2, 6
   • Chronic: Transition to hydroxychloroquine, sulfasalazine, azathioprine, or low-dose prednisone 1

4. Is injectable administration necessary?

   • No—oral NSAIDs have equivalent efficacy with better-studied safety profiles in pregnancy 4