Prompt recognition of anaphylactic reactions to a peanut exposure is critical to prevent adverse outcomes. Immediate administration of epinephrine, preferably in the lateral thigh, is absolutely critical to reduce morbidity and mortality: 0.01 mg/kg up to 0.5 mg intramuscularly (IM) or subcutaneously with repeat dose in 10-15 minutes if needed. If using epinephrine at 1:1000, this would be 0.01 mL/kg up to 0.5 mL.
For epinephrine autoinjectors:
- 0.1 mg (if this strength is available) for patients weighing 7.5-15 kg
- 0.15 mg for patients weighing 15-30 kg
- 0.3 mg for patients weighing more than 30 kg
Rapid assessment and attention to the ABCs (airway, breathing, and circulation) is critical. If the patient is not already in an emergency room or hospital, emergency medical service (EMS) should be activated. Airway management and stabilization may require intubation, which may be difficult if angioedema is present. In extreme cases, cricothyroidotomy may be needed.
Patients should be placed on cardiopulmonary monitors with continuous pulse oximetry. Oxygen should be administered at 8-10 L/min via face mask if hypoxia is present. Large bore intravenous (IV) lines should be established with rapid normal saline infusion of 10-20 cc/kg bolus if hypotension is present and repeated up to a total of 40 cc/kg as needed. If hypotension persists, IV pressors may be needed in addition to further normal saline fluid boluses. Nebulized albuterol should be administered if wheezing persists despite epinephrine administration. Diphenhydramine should be given IV or IM at 1 mg/kg up to 50 mg. If available, IV cetirizine can be given in place of diphenhydramine at a dose of 2.5 mg for patients aged 6 months to 5 years, 5 mg for ages 6-11 years, and 10 mg for ages 12 years and older. Administration of famotidine at 0.25 mg/kg to a maximum of 20 mg can also be given. Glucocorticoid administration may also be of benefit but is controversial and lacks evidence to support its use.
Diagnosis Overview:
Peanut allergy initially presents between ages 4 months and 2 years and affects up to 1 in 50 children, with increasing incidence over the past 2 decades. Children with a history of atopy or egg allergy, family history of food allergies, and history of maternal consumption of peanuts during pregnancy are at increased risk of developing peanut allergy. Peanut allergy is an immunoglobulin E (IgE)-mediated hypersensitivity reaction with symptoms ranging from mild urticaria to severe, life-threatening anaphylactic reactions. Common symptoms include skin erythema, edema, and urticarial lesions. More severe reactions include swelling / tingling of the lips, mouth, throat, or tongue; vomiting; diarrhea; wheezing; dyspnea; cough; cyanosis; and mental status changes. Most symptoms will appear within minutes of exposure up to 2 hours postexposure. The diagnosis is suspected on history of peanut exposure with development of symptoms within 2 hours of exposure. The diagnosis can be confirmed by a combination of skin patch, IgE peanut-specific antibody, and/or food challenge.
Treatment depends on severity of symptoms and ranges from use of an antihistamine for mild skin erythema or urticaria to IM epinephrine and other medications discussed in the Emergent Care section above for multisystem or severe symptoms. Successive exposure may portend more severe reactions. Up to 20% of children with peanut allergy may become tolerant as adults; however, the remaining 80% remain allergic. Recent studies have shown that early introduction of peanut products for some infants (beginning at age 4-6 months), with continued ongoing exposure, significantly helps to reduce the likelihood of developing a peanut allergy.
