What are the contraindications to diclofenac?

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Last updated: November 7, 2026 • View editorial policy

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Contraindications to Diclofenac

Diclofenac is absolutely contraindicated in patients undergoing coronary artery bypass graft (CABG) surgery, those with known hypersensitivity to diclofenac or other NSAIDs, and patients with a history of aspirin-sensitive asthma or allergic-type reactions to NSAIDs 1.

Absolute Contraindications

The FDA drug label clearly defines the following as absolute contraindications 1:

1. Perioperative CABG Surgery

  • Do not use diclofenac for treatment of perioperative pain in the setting of CABG surgery
  • This carries a black box warning due to increased cardiovascular thrombotic events 1

2. Hypersensitivity Reactions

  • Known hypersensitivity to diclofenac or any drug product components
  • Includes patients who have experienced anaphylactic reactions or serious skin reactions (Stevens-Johnson Syndrome, toxic epidermal necrolysis, exfoliative dermatitis) to diclofenac 1

3. Aspirin-Sensitive Asthma

  • History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs
  • These patients can experience severe, sometimes fatal anaphylactic reactions
  • This includes the aspirin triad: chronic rhinosinusitis with nasal polyps, severe bronchospasm, and NSAID intolerance 1

Cardiovascular Contraindications (European Regulatory Standards)

While the FDA labels these as warnings rather than absolute contraindications, European regulatory authorities established cardiovascular disease as contraindications in 2013 2, 3. These include:

  • Congestive heart failure (NYHA class II-IV)
  • Ischemic heart disease (including prior myocardial infarction)
  • Peripheral arterial disease
  • Cerebrovascular disease (including prior stroke)

Critical Context on Cardiovascular Risk

Diclofenac carries particularly high cardiovascular risk compared to other NSAIDs. The evidence shows 4:

  • Vascular events: RR 1.63 (95% CI: 1.12-2.37) vs placebo
  • Cardiovascular events/MI: RR 1.40 (95% CI: 1.16-1.70)
  • Recurrent MI: RR 1.54 (95% CI: 1.23-1.93)
  • Mortality: RR 2.40 (95% CI: 2.09-2.80)

These risks are among the highest of all NSAIDs, approaching those of selective COX-2 inhibitors.

Pregnancy Contraindications

Avoid diclofenac at ≥30 weeks gestation due to risk of premature closure of fetal ductus arteriosus 1.

Use with extreme caution at ≥20 weeks gestation due to risk of fetal renal dysfunction, oligohydramnios, and neonatal renal impairment 1.

Relative Contraindications/High-Risk Situations

The following warrant avoiding diclofenac unless benefits clearly outweigh risks 1:

  • Severe heart failure - monitor closely if used
  • Advanced renal disease - may hasten progression of renal dysfunction
  • Active peptic ulcer disease or GI bleeding history - elderly patients at particularly high risk
  • Hepatic impairment - increased risk of renal toxicity
  • Dehydration or hypovolemia - correct volume status before initiating

Important Clinical Pitfalls

Despite clear regulatory warnings established in 2013, research demonstrates that more than 1 in 10 patients initiated on diclofenac have cardiovascular contraindications 3. Studies from multiple European countries show continued prescribing to patients with contraindications, suggesting limited real-world impact of risk minimization measures 5, 2, 3.

Key takeaway: The high cardiovascular mortality risk (RR 2.40) combined with evidence showing diclofenac offers no superior efficacy over safer alternatives means it should rarely be a first-line choice, particularly in patients with any cardiovascular risk factors.

References

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.