What should I do if I experience itching after taking aspirin (acetylsalicylic acid)?

Management of Aspirin-Induced Itching

If you experience itching after taking aspirin, you should discontinue the medication immediately and consult a healthcare provider, as this may indicate an allergic reaction that could potentially progress to more serious symptoms. 1

Types of Aspirin Hypersensitivity Reactions

Aspirin-induced itching typically falls into one of several hypersensitivity patterns:

1. NSAID-exacerbated cutaneous disease:

   • Common in patients with chronic spontaneous urticaria (10-40% of these patients react to aspirin)
   • Characterized by worsening of pre-existing urticaria or angioedema
   • Involves cross-reactivity with other COX-1 inhibitors 2

2. Single NSAID-induced urticaria/angioedema:

   • Specific reaction to aspirin alone
   • Other NSAIDs may be tolerated 2

3. Aspirin-exacerbated respiratory disease (AERD):

   • Includes bronchoconstriction and rhinitis symptoms
   • More common in patients with asthma and nasal polyps 2

Evaluation Algorithm

When experiencing itching after aspirin:

1. Assess severity and associated symptoms:

   • Mild localized itching only
   • Itching with hives/urticaria
   • Itching with angioedema (swelling)
   • Itching with respiratory symptoms (wheezing, shortness of breath)
   • Itching with systemic symptoms (dizziness, hypotension)

2. Determine timing of reaction:

   • Immediate (within minutes to 3 hours of ingestion) suggests true hypersensitivity 3
   • Delayed reactions (>6 hours) may indicate a different mechanism 2

3. Review medical history:

   • History of chronic urticaria (increases risk by 23%) 3
   • History of asthma (increases risk by 4-19%) 3
   • History of nasal polyps (increases risk by 23%) 3

Management Recommendations

Immediate Actions:

1. Stop taking aspirin immediately if itching occurs 1
2. Seek medical help right away if you experience:
   • Widespread hives
   • Facial/throat swelling
   • Difficulty breathing
   • Dizziness/feeling faint 1

Alternative Medications:

1. For patients needing anti-inflammatory or analgesic therapy:

   • Acetaminophen (paracetamol) in low to moderate doses (<1000mg) is generally safe for most aspirin-sensitive individuals 4
   • Selective COX-2 inhibitors (celecoxib) are well tolerated by almost all aspirin-sensitive patients 4, 5
   • Preferential COX-2 inhibitors (nimesulide, meloxicam) are tolerated by the majority but not all hypersensitive patients 4

2. For patients with chronic urticaria exacerbated by aspirin:

   • High-dose antihistamines (2-4 times standard dose of non-sedating antihistamine) may allow occasional NSAID use 2
   • Selective COX-2 inhibitors are generally well tolerated 2, 6

Special Considerations:

1. For patients requiring aspirin for cardiovascular protection:

   • Aspirin desensitization may be considered under medical supervision 4
   • This should only be performed by specialists in a controlled setting 2

2. For patients with aspirin-exacerbated respiratory disease (AERD):

   • Formal desensitization protocols exist and may be beneficial 2
   • These typically require 1-3 days in a controlled medical setting

Important Caveats

• Cross-reactivity: Patients who react to aspirin often react to other NSAIDs that inhibit COX-1 (indomethacin, ibuprofen, naproxen) 3, 6
• Not a true allergy: Most aspirin hypersensitivity reactions are not IgE-mediated allergies but involve alterations in arachidonic acid metabolism 2, 6
• Aspirin does not help itching: Contrary to what some might think, aspirin does not relieve itching from chronic dermatoses and may worsen it in sensitive individuals 7
• Desensitization is temporary: If aspirin desensitization is performed, continued daily therapy is required to maintain tolerance 2

Remember that aspirin hypersensitivity can range from mild skin reactions to severe, life-threatening anaphylaxis. Any itching after taking aspirin should be taken seriously as it may be the first sign of a more severe reaction.