Can I use Voltaren (diclofenac) gel if I am allergic to aspirin?

Using Voltaren Gel with Aspirin Allergy

If you have a history of aspirin allergy, you should avoid using Voltaren (diclofenac) gel due to potential cross-reactivity, as diclofenac belongs to the acetic acid class of NSAIDs which can trigger similar hypersensitivity reactions as aspirin. 1, 2

Understanding NSAID Classification and Cross-Reactivity

Aspirin and diclofenac belong to different chemical classes of NSAIDs but share similar mechanisms of action through COX-1 inhibition:

• Aspirin belongs to the salicylate class
• Diclofenac belongs to the acetic acid class 1

The FDA label for diclofenac specifically lists a history of allergic reactions to aspirin as a contraindication, stating: "Diclofenac is contraindicated in patients with history of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs." 2

Types of Aspirin/NSAID Hypersensitivity Patterns

Your risk depends on the type of aspirin allergy you have:

1. Cross-reactive (non-immunologic) reactions:

   • NSAID-exacerbated respiratory disease (AERD): Involves respiratory symptoms
   • NSAID-exacerbated cutaneous disease: Worsening of pre-existing urticaria/angioedema
   • Multiple NSAID-induced urticaria/angioedema: In patients without underlying chronic urticaria

2. Single NSAID (immunologic) reactions:

   • Specific to one NSAID chemical class
   • Less common than cross-reactive patterns 1, 3

Risk Assessment for Topical Diclofenac

While topical diclofenac has lower systemic absorption than oral formulations, the risk of reaction still exists:

• Topical diclofenac may have less systemic effect on platelet function compared to oral diclofenac 4
• However, even with lower absorption, topical NSAIDs can still trigger hypersensitivity reactions in susceptible individuals
• The 2022 practice parameter update from the Journal of Allergy and Clinical Immunology does not specifically exempt topical NSAIDs from cross-reactivity concerns 1

Safer Alternatives

If you need pain relief and have aspirin allergy, consider:

• Acetaminophen (paracetamol) at moderate doses (<1000mg) is generally well-tolerated 5
• Selective COX-2 inhibitors like celecoxib are tolerated by most (but not all) aspirin-sensitive patients 3, 5

Important Precautions

• The severity of your previous reaction to aspirin should guide decision-making
• Patients with severe cutaneous reactions or anaphylaxis to aspirin should be particularly cautious with any NSAID, including topical formulations
• Diclofenac has been specifically associated with severe cutaneous adverse drug reactions 1

If you absolutely require an NSAID for pain management, consult with an allergist-immunologist who can:

• Determine your specific type of aspirin hypersensitivity
• Consider supervised challenges with alternative medications if appropriate
• Discuss aspirin desensitization if you require long-term NSAID therapy 3