What to do in case of a Diclofenac (NSAID) allergic reaction?

Management of Diclofenac (NSAID) Allergic Reaction

In case of a diclofenac allergic reaction, immediately stop the medication and provide treatment based on the severity of symptoms, with epinephrine as first-line therapy for severe reactions. 1

Classification of Reactions

Mild Reactions (Grade I)

• Cutaneous symptoms only: rash, urticaria, pruritus, flushing 1
• Treatment:
  • Discontinue diclofenac immediately 2
  • Administer oral antihistamines for symptom relief 1
  • Monitor for progression of symptoms 1

Moderate Reactions (Grade II)

• Cutaneous symptoms plus hypotension, tachycardia, or respiratory symptoms 1
• Treatment:
  • Administer IV epinephrine 20 μg (0.2 mL of 1:10,000) 1
  • Consider IV epinephrine 50 μg at 2 minutes if unresponsive to initial dose 1
  • Administer crystalloid 500 mL as rapid bolus 1
  • Administer IV antihistamines after adequate epinephrine and fluid resuscitation 1

Severe Reactions (Grade III - Life-threatening)

• Hypotension, bronchospasm, or significant angioedema 1
• Treatment:
  • Administer IV epinephrine 50-100 μg 1
  • Increase to 200 μg at 2 minutes if unresponsive 1
  • Administer crystalloid 1 L as rapid bolus 1
  • Consider additional vasopressors if persistent hypotension after 10 minutes 1

Cardiac/Respiratory Arrest (Grade IV)

• Treatment:
  • Follow advanced life support guidelines including IV epinephrine 1 mg 1
  • Initiate cardiac compressions 1
  • Consider extracorporeal life support in refractory cases 1

Post-Reaction Management

Immediate Care

• Observe patient in a monitored area for a minimum of 6 hours or until stable 1
• Document the reaction in detail in medical records 1
• Consider tryptase testing: first sample at 1 hour, second at 2-4 hours, baseline sample after 24 hours 1

Long-term Management

• Avoid diclofenac and consider cross-reactivity with other NSAIDs 1, 2
• For very severe life-threatening reactions (anaphylaxis), the implicated drug should not be used again 1, 2
• Consider consultation with an allergist for further evaluation 1

Cross-Reactivity Considerations

• NSAIDs are classified based on chemical structure, and cross-reactivity often occurs within the same structural class 1
• Diclofenac is an acetic acid derivative NSAID 1
• Patients with true allergic reactions to diclofenac may need to avoid other NSAIDs in the same chemical class 1
• For patients requiring anti-inflammatory therapy, consider:
  • NSAIDs from a different chemical class under medical supervision 1
  • Selective COX-2 inhibitors which are generally better tolerated in patients with NSAID hypersensitivity 1

Special Considerations

• Patients with aspirin-sensitive asthma have increased risk of cross-reactivity with all NSAIDs 2
• Diclofenac is contraindicated in patients with known hypersensitivity to diclofenac or history of allergic reactions after taking aspirin or other NSAIDs 2
• Fatal anaphylactic reactions to diclofenac have been reported, highlighting the importance of prompt recognition and treatment 3, 4
• Both immediate (IgE-mediated) and delayed hypersensitivity reactions (Type IV) can occur with diclofenac 5, 6

Diagnostic Testing (After Recovery)

• Skin testing may be helpful for some NSAIDs but is not standardized for diclofenac 1, 5
• Intradermal testing may be more reliable than skin prick testing for some drugs 1
• Challenge testing should only be performed by specialists in appropriate settings with emergency equipment available 1