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Several points may be helpful to remember when responding to allergic reactions in the field. In general, stinging insects, especially Hymenoptera, can cause systemic allergic reactions and anaphylaxis, but these reactions are rare with biting insects [18]. There is a greater chance of a systemic reaction with multiple stings. One should remember that the clinical presentation may be quite varied and the history may be vague. Patients may have significant symptoms yet not be able to recall exposure to a specific allergen. In cases such as these, interventions necessary for stabilization should take priority over identification of the culprit allergen. In cases of true anaphylaxis, the axiom “stabilize first, diagnose later” should be followed. After emergency interventions are completed, care should be taken to frequently reassess the patient and document pertinent findings. This may be the first clue that an allergic reaction is present if the patient does not relate an exposure or inciting event. Symptoms can be exacerbated by fear, exercise, alcohol intake, heat exposure, or underlying cardiovascular disease. The clinician should be careful not to become complacent or attribute clinical signs and symptoms solely to these conditions, as allergic reactions can progress insidiously.

Anaphylaxis to stings can occur abruptly years after the first exposure, even without intervening stings. Furthermore, approximately 20% of patients exhibit biphasic anaphylaxis responses where the initial symptoms resolve and there is a symptom‐free period before the onset of the late phase reaction 4‐6 hours after the initial symptoms began. The symptoms of the late reaction can be markedly different from those of the initial reaction, and can be life‐threatening even if those of the initial reaction were not. It is nearly impossible to predict which patients will exhibit this biphasic response. This could result in repeat EMS calls for allergic reactions featuring substantially different symptoms, particularly if a patient refuses transport initially or is seen and discharged from an ED before the late phase reaction occurs [19].

If the patient experiencing a severe allergic reaction or anaphylaxis routinely takes beta‐blocker medications, the action of epinephrine may be blunted. Glucagon may be given in 1 mg increments by any parenteral route to overcome the effects of beta‐blockade. Cutaneous symptoms are the most common clinical response in both adults and children. Hypotension is uncommon in children, but it has been reported in up to 60% of adults with significant allergic reactions. Patients will sometimes complain of a prodrome of chest pain or shortness of breath before development of a more generalized severe allergic reaction.

EMS clinicians should have a high index of suspicion when responding to calls of shortness of breath or chest pain. Attempt to ensure there was no contact with an allergen that could cause the symptoms. For instance, allergy‐producing contrast media are frequently given in free‐standing imaging centers. Consider the possibility of allergic reactions and anaphylaxis when responding to calls of shortness of breath or chest pain at these facilities [20]. Anaphylaxis should be one of the etiologies considered when responding to cardiac arrests in outdoor areas, such as golf courses, as the patient may have been stung or bitten before the cardiac arrest.

Although bites from a Gila monster are infrequent, allergic reactions can occur. If it is still attached to the patient, the clinician should remove it by prying its jaws apart with a stick or metal object, holding a flame under the lizard’s chin, or submerging it in cold water [21]. Obviously, care should be taken to avoid additional bites to the patient or EMS personnel.

To determine the most appropriate destination facility for allergic reaction patients, it helps to consider the etiology of the reaction and the availability of certain subspecialties, such as otolaryngology, anesthesia, critical care, toxicology, and so on. They may be necessary to definitively treat the reaction. Transportation time should also be considered. If the patient is unstable or is likely to become unstable during an extended transport time to an appropriate facility, then air medical evacuation should be considered. Transport to the closest available facility for stabilization followed by transfer of the patient to a higher level of care is also an option. This will depend on the availability of air medical services, the distance to the closest facility, weather, traffic, terrain, and other conditions that must be factored in when making destination decisions.