Disclaimer: This article is intended solely for informational and educational purposes only. It does not constitute medical advice.
Being allergic to medication is not uncommon, and it can complicate clinical care, especially in the context of anesthesia and surgery. Fortunately, true allergic reactions to anesthesia are rare. However, because they do still occur, it is important for clinicians and patients to be aware of and recognize signs of an allergy to improve patient safety.
According to the Anesthesia Patient Safety Foundation (APSF), allergic reactions to anesthesia can be categorized into several groups (APSF, 2025). The most familiar type is an IgE-mediated allergic reaction, sometimes called a “classic allergy.” In this case, the immune system produces IgE antibodies that trigger the release of histamine, usually within minutes of drug exposure. Symptoms can include hives, flushing, swelling, difficulty breathing, a rapid heart rate, or a sudden drop in blood pressure that causes dizziness or fainting (APSF, 2025).
In its most severe form, this reaction becomes anaphylaxis, a medical emergency requiring immediate treatment with epinephrine and supportive care (Mertes & Laxenaire, 2002). A less common, delayed form of allergy involves T-cells rather than IgE antibodies and can produce rashes, fever, joint pain, or gastrointestinal symptoms hours or even days after a drug is given (APSF, 2025).
Research suggests that anesthesia-related anaphylaxis is rare, occurring in roughly 1 in 10,000 to 1 in 20,000 procedures (Mertes & Laxenaire, 2002). When an allergic reaction does occur during surgery, it is important to identify the specific drug class causing the reaction.
Neuromuscular blocking agents, which are used to relax muscles during surgery, are frequently implicated, according to data from Europe and Australia (Mertes & Laxenaire, 2002), while research in the US has identified antibiotics given around the time of surgery as being the most common cause of perioperative allergy, rather than anesthetics (Gurrieri et al., 2011). Other agents sometimes involved in allergic reactions include latex, chlorhexidine antiseptic, and, less often, benzodiazepines such as midazolam, which are used for sedation (Gąsiorowska et al., 2026).
It is worth noting that many reactions that look like allergies are not caused by the immune system at all. Some drugs, including certain opioid pain medications, can trigger the direct release of histamine from mast cells without any antibody involvement, producing flushing, itching, or a temporary drop in blood pressure that mimics an allergic reaction (Baldo & Pham, 2012).
These pseudoallergic reactions are fairly common but rarely dangerous, and they are treated differently than true allergies. Likewise, common postoperative symptoms such as nausea, sore throat, or grogginess are ordinary side effects of anesthesia and typically not allergic responses (APSF, 2025).
Because distinguishing a true allergy from a side effect can be difficult in the moment, and because immediate intervention is needed in the case of anaphylaxis, anyone with a history of allergies, asthma, eczema, or a previous reaction during anesthesia should share that history with their anesthesia provider before surgery (APSF, 2025). When a reaction is suspected, doctors will later refer patients for allergy skin testing to identify the responsible drug, since testing performed too soon or too late after a reaction can produce misleading results (Gurrieri et al., 2011).
While it is possible to be allergic to anesthesia, it is uncommon, and modern anesthesia care includes safeguards, careful monitoring, and emergency protocols designed to catch and treat these reactions quickly. Patients who have questions or concerns about a past reaction should raise them with their surgical and anesthesia team well before their procedure.
References
- Anesthesia Patient Safety Foundation. (2025, May 1). Can I be allergic to anesthesia? https://www.apsf.org/patient-guide/can-i-be-allergic-to-anesthesia/
- Baldo, B. A., & Pham, N. H. (2012). Histamine-releasing and allergenic properties of opioid analgesic drugs: Resolving the two. Anaesthesia and Intensive Care, 40(2), 216–235. https://doi.org/10.1177/0310057X1204000204
- Gąsiorowska, J., Kiełczyńska, E., Dziamara, W., Grundys, A., Drozdowska, J., Woźny, M., Skiba, A., & Gomułka, K. (2026). Hypersensitivity reactions to benzodiazepines used for perioperative premedication: A narrative review. Pharmaceuticals, 19(3), 507. https://doi.org/10.3390/ph19030507
- Gurrieri, C., Weingarten, T. N., Martin, D. P., Babovic, N., Narr, B. J., Sprung, J., & Volcheck, G. W. (2011). Allergic reactions during anesthesia at a large United States referral center. Anesthesia & Analgesia, 113(5), 1202–1212. https://doi.org/10.1213/ANE.0b013e31822d45ac
- Mertes, P. M., & Laxenaire, M.-C. (2002). Allergic reactions occurring during anaesthesia. European Journal of Anaesthesiology, 19(4), 240–262. https://doi.org/10.1017/S0265021502000418
