Epinephrine ‘first line’ for food anaphylaxis

New federal guidelines on food allergy recommend prompt and rapid treatment of food-induced anaphylaxis with intramascular epinephrine as first-line therapy.

And in cases of a suboptimal response to epinephrine — or if symptoms progress — repeat epinephrine dosing remains first-line therapy over adjunctive treatments.

The consistency and strength of the recommendation for prompt treatment with IM epinephrine may come as a surprise to some emergency physicians who reserve treatment with epinephrine until patients are in shock, which is an extreme and late manifestation of anaphylaxis, says an emergency physician who served on multidisciplinary panel that developed the guidelines for National Institute of Allergy and Infectious Disease.

“Earlier diagnosis of anaphylaxis and earlier treatment with epinephrine would benefit patients according to the Massachusetts General Hospital and Harvard Medical School, both in Boston. The guidelines strongly encourage earlier use of IM epinephrine for food-included anaphylaxis.

The guidelines were based on a systematic literature review combined with consensus expert opinion, and were designed to standardize the diagnosis and management of food allergies across clinical setting disciplines.

Expert opinion played a prominent role in the development of the guidelines — particularly in section on managing acute allergic reactions to food-included anaphylaxis management, the 25-member expert panel said.

Anaphylaxis, whether food induced or not, is significantly underrecognized and undertreated. One possible reason is the failure to appreciate that anaphylaxis can present without obvious cutaneous symptoms, which happens in 10%-20% of cases, or without overt shock.

Food-included anaphylaxis can occur within minutes to several hours after a defined exposure to a food allergen. Deaths from food-induced anaphylaxis have been reported within 30 minutes to 2 hours of exposure, and are associated with delayed use of epinephrine or improper epinephrine dosing.

The guidelines, which include guidelines and dosing information for epinephrine and adjunctive treatments — from inhaled bronchodilators and antihistamines to vasopressors and glucagons — caution specifically against use of H1 and H2 antihistamines for anaphylaxis in anything but an adjunctive role.

Antihistamines such as diphenhydramine are commonly used to treat anaphylaxis, but the report noted that data demonstrating their effectiveness are lacking. Similarly there is no persuasive evidence for the use of corticosteroids in acute food-related allergic reaction.

Epinephrine has an onset of action within minutes but is rapidly metabolized. Repeated doses of epinephrine may therefore be required after 5-15 minutes, the guidelines say. Among individuals who required epinephrine for anaphylaxis, approximately 10%-20% will require more than one dose.

The panel acknowledge in its report that some level of decision making regarding the risk-benefit ratio of epinephrine may be warranted for some patients but emphasized that severe adverse effects are rare with epinephrine and are more likely to occur when it is given in overdose than in other circumstances.

Because the risk of the deaths or serious disability from anaphylaxis itself usually outweighs other concerns, existing evidence clearly favors the benefit of epinephrine administration in most situations, the guidelines states.

IM injection of epinephrine should be quickly followed by placement of the patient in a recumbent position (if tolerated, and with lower extremities elevated), the provision of supplement oxygen and the administration of intravenous fluid.

And although little is known about the most effective method in educating and protecting patients at risk for food-induced anaphylaxis, the guidelines recommend a thorough discharge plan following treatment for food-induced anaphylaxis — one that includes a plan for arranging further evaluation, an anaphylaxis emergency action plan, and an epinephrine auto-injector (two doses) with instructions and a plan for monitoring auto-injector expiration dates.