When the patient is seen for an emergency procedure, the time before surgery is too short to properly investigate the patient for allergies. Anesthesia must then take place in a latex-free environment. If the previous reaction occurred during a general anesthesia, local-regional anesthesia should be considered. When local-regional anesthesia is not an option, NMBAs and histamine-releasing products should be avoided whenever possible.

For surgery and/or patients with a low risk of infectious complications, avoidance of the pharmaceutical class of antibiotics is effective.

The situation is more complicated in the case of beta-lactam allergy in patients with a specific beta-lactam requirement (see above). A proper allergic assessment is not possible because of the emergency setting. The switch to another pharmaceutical class is possible but associated with a higher risk of clinical failure [35]. In the case of self-reported penicillin allergy, hypersensitivity reactions to cefepime and carbapenems are rare, and these antibiotics should be considered as a potential treatment for infectious complications [36]. When the patient is suspected to be allergic to an antibiotic but requires a specific treatment by this antibiotic (e.g., in the case of multidrug-resistant bacteria), a rapid desensitization has been proposed with incremental doses of antibiotics. Immune tolerance only lasts for the time of the therapy [37].

Patients claiming to be allergic to latex or at risk of latex allergy (atopy, latex-fruit syndrome, spina bifida, multiple surgeries) must be referred to an allergy specialist. If the latex allergy is confirmed or if the time between anesthetic assessment and surgery is not compatible with an allergic assessment, the patient must be operated first on the list and a latex-free environment is mandatory. All relevant parties should be warned of the patient’s allergy [6]. An updated list of latex-containing equipment must be available in the anesthesiology department.

Morphine and codeine phosphate are known to induce non-specific skin mast cell activation resulting in pruritus, urticaria, and mild hypotension. This histamine-releasing effect explains why allergic reactions to opioids are overreported. IgE-mediated reactions to morphine and codeine are rare but remain possible. There is no evidence for cross-reactivity between different subclasses of opioids (phenanthrenes, phenylpiperidines, and diphenylheptanes), but cross-reactivity between morphine and codeine is frequent [38]. Patients claiming an allergy to morphine or codeine should be referred to an allergy specialist for assessment and skin tests. Because of the histamine-releasing effect of morphine and codeine, skin tests are difficult to interpret, and the maximal recommended concentration should not be exceeded. A challenge test should be considered when skin tests are not conclusive [5]. If the patient is allergic to morphine or codeine, they are both contraindicated, but other opioids remain available [6].

Iodine is not an antigenic determinant per se. The patient may be allergic to iodinated contrast media or to povidone-iodine, used as skin disinfectant. The patient should be questioned in order to determine whether the reaction occurred during an imaging session or skin disinfection.

If iodinated contrast media are suspected, the patient should be investigated using skin tests and in vitro tests for diagnosis of both immediate and non-immediate reactions. Drug provocation tests are possible. Cross-reactivity between iodinated contrast media is frequent and this should be considered for testing [39].

Hypersensitivity to povidone-iodine is rare. The allergenic determinant is mainly povidone for immediate hypersensitivity reactions, but nonoxynol may also be involved in non-immediate hypersensitivity reactions. Skin tests are useful for diagnosis. In the case of allergy to povidone-iodine, an avoidance strategy is appropriate. Other skin disinfectants such as chlorhexidine can be used. There is currently no evidence for cross-reactivity between iodinated drugs.

There is no relation between seafood allergy and iodinated drug allergy. These drugs can be used safely in patients declaring seafood allergies [40].

Protamine sulfate is frequently responsible for non-IgE-mediated hypersensitivity reactions. Protamine allergy is also possible and protamine sulfate is contraindicated if the allergy is documented. Conversely there is no evidence suggesting that protamine sulfate should be avoided in case of fish allergy [6, 41].

Egg lecithin and soy oil are currently used for the fatty emulsified formulation of propofol. Although rare, several cases of propofol hypersensitivity reactions have been described, and some of them were attributed to cross sensitization with food allergies. Food allergies are increasing in the general population and egg and soy are often found to be responsible for these allergies. Anesthetists exclude propofol from the anesthetic protocol because of the fear of cross-reactions between food allergies to soy or egg and propofol.

There is currently no evidence to support this assumption. Two recent studies showed that the use of propofol in patients with egg or soy allergy was not associated with an increased risk of hypersensitivity reaction, so propofol appears to be safe for these patients [42, 43].

Red meat allergy is rare (only 3% of food allergies) and beef is the most common meat allergy. This allergy is associated with hypersensitivity reactions to bovine-derived gelatin drugs such as gelatin colloids or the stabilizing agents in some vaccines. The carbohydrate determinant galactose-alpha-1,3-galactose (alpha-gal) was found to be a potential mediator of the onset of red meat allergy. Consequently, gelatin colloids should be avoided in patients reporting a red meat allergy [44, 45].

Cross sensitization between peanut and anesthetic drugs has never been described. No adjustment is required in these patients.

Immediate hypersensitivity reactions are recognizable by the association of suggestive symptoms (Table 20.2) and a chronological relation between exposure to an antigen and the reaction.