Anaphylaxis Mimics: When It Looks Like Anaphylaxis But Isn't
May 25, 2026
Not every sudden deterioration in the perioperative setting is anaphylaxis. Yet in the moment, it can look very similar.
Hypotension, tachycardia, bronchospasm, and skin changes can all point toward anaphylaxis. But these signs are not exclusive. Several other conditions can present in ways that closely resemble it, especially under anaesthesia where the patient cannot describe symptoms.
Understanding these mimics helps guide safer, more accurate responses.
Many anaphylaxis-like presentations are driven by different underlying mechanisms. Vasovagal episodes can cause sudden hypotension and bradycardia. Drug effects, particularly from anaesthetic agents, may lead to cardiovascular instability. Bronchospasm may occur in patients with reactive airways, and conditions like pulmonary embolism or myocardial events can present with rapid deterioration.
The overlap can be subtle.
- ⚡ Vasovagal reactions often include bradycardia rather than tachycardia
• ⚡ Drug-induced hypotension may occur without airway or skin involvement
• ⚡ Bronchospasm alone does not confirm anaphylaxis
• ⚡ Pulmonary embolism may present with sudden hypoxia and cardiovascular collapse
• ⚡ Serum tryptase can support diagnosis but is not immediately available
In practice, initial management often proceeds as presumed anaphylaxis. This is appropriate, as delayed treatment carries risk. At the same time, ongoing assessment is essential to reconsider the diagnosis as more information becomes available.
For perianaesthesia nurses, this means staying both responsive and reflective. Acting quickly, while also observing patterns, trends, and responses to treatment.
Not every presentation will follow the expected path.
Holding an open clinical perspective allows the team to adjust, refine, and provide care that matches the true cause of deterioration.
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References:
Egner, W., Helbert, M., Sargur, R. (2021). Diagnostic approach to perioperative anaphylaxis and its mimics. Clinical and Experimental Allergy.
McDonnell, N.J., et al. (2026). Anaphylaxis and its mimics in the perioperative setting. European Journal of Anaesthesiology.
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