Contraindications to ASA Load Therapy
Acetylsalicylic acid (ASA) loading is contraindicated in patients with active bleeding, hemophilia, ASA allergy (particularly asthma with nasal polyps), active peptic ulcer disease, severe untreated hypertension, and active retinal or serious gastrointestinal/genitourinary bleeding. 1
Absolute Contraindications
Bleeding Disorders and Active Hemorrhage
- Active bleeding from any source represents an absolute contraindication to ASA loading 1
- Hemophilia or other inherited coagulation disorders preclude ASA use 1
- Active retinal bleeding is specifically listed as a contraindication 1
Hypersensitivity Reactions
- True ASA allergy, primarily manifested as asthma with nasal polyps, is an absolute contraindication 1, 2
- Patients with aspirin-exacerbated respiratory disease (asthma, nasal polyps, rhinosinusitis) have particularly high risk of life-threatening bronchospasm 2
- ASA intolerance that causes significant symptoms also contraindicates loading 1
Active Gastrointestinal Pathology
- Active peptic ulcer disease is a contraindication to ASA loading 1
- Serious gastrointestinal bleeding sources preclude ASA administration 1
- Recent significant bleeding from gastritis represents a contraindication 1
Cardiovascular
- Severe untreated hypertension must be controlled before initiating ASA 1
Management of ASA-Allergic Patients with ACS
When ASA is contraindicated but antiplatelet therapy is essential (such as in acute coronary syndromes):
Primary Alternative Strategy
- Use clopidogrel alone indefinitely as the primary alternative antiplatelet agent 1
- For clopidogrel-allergic patients, ticlopidine 250 mg twice daily can be substituted 1
ASA Desensitization Option
- ASA desensitization can be attempted in patients with true allergy when ASA is critically needed 1, 2
- Important caveat: sensitivity may recur despite continuous therapy after successful initial desensitization 2
- Patients with uncontrolled or severe asthma should avoid desensitization due to increased risk of severe exacerbations 2
Relative Contraindications and Special Considerations
Genitourinary Bleeding
- Active serious genitourinary bleeding is a contraindication 1
Drug Interactions
- Ibuprofen interaction: Patients must take ibuprofen at least 30 minutes after immediate-release ASA or at least 8 hours before ASA to avoid diminishing ASA's protective effects 1
- No specific recommendations exist for enteric-coated ASA with ibuprofen 1
Common Pitfalls to Avoid
Do not confuse ASA intolerance with true allergy: Patients who regularly use NSAIDs without problems can generally tolerate ASA, but should be warned that intolerance can develop later in life 2. A careful history distinguishing true allergic reactions from gastrointestinal side effects is essential.
Do not assume all "ASA allergies" are absolute contraindications: Many reported ASA allergies are actually intolerances (dyspepsia, nausea) that occur infrequently with low doses and may not preclude careful ASA administration 1.
Gastrointestinal side effects are dose-dependent: While dyspepsia and nausea can occur, they are infrequent with the low maintenance doses (75-162 mg) used for antiplatelet therapy 1