Management of Allergic ReactionsPresentation

The diagnosis of Allergic reactions is a clinical one. Individuals usually experience symptoms soon after exposure but the response may be delayed by several hours. These patients need to be treated urgently and need continuous monitoring to provide care for emerging symptoms in a timely manner. Allergic reaction triggers the release of IgE immunoglobulin. This IgE release causes vasodilatation, airway swelling, and capillary leakage leading to hypotension. It usually involves one or more body systems and produces one or more symptoms such as hives, flushing, itching, angioedema, stridor, wheezing, shortness of breath, vomiting, diarrhea or shock. Patients may also report a frightening feeling of “impending doom”.

Treatment

Intravenous fluids are necessary for appropriate treatment to prevent hypotension due to leaking capillaries and vasodilation. Blood pressure monitoring is also important in the management of these patients. You may consider and discuss with your attending the use of vasopressors if hypotension does not respond to IV fluids.

H1–receptor blockers: H1 histamine receptors are found in smooth muscle cells throughout the body, and they lead to a traditional allergic reaction when histamine is bound to them. Histamine is released during an allergic reaction therefore they were developed to counteract the allergic symptoms by blocker the Histamine receptors. The most common example of a first-generation histamine blocker is diphenhydramine (Benadryl). Benadryl 25-50mg by mouth every 6 hours is indicated while in ED and CDU with recommendation to continue at home. A side effect is sedation that may be severe depending on the patient.

Second Generation H1 blockers: Because of the sedative effect of first-generation histamine blockers, second-generation H1 histamine receptor blockers are available and include loratadine (Claritin) and fexofenadine (Allegra).

H2-receptor blockers: When given in combination with H1 blockers, H2 receptor blockers can be helpful in alleviating allergic reactions. They also reduces potential gastric upset when steroids are given for allergic reactions.

Nebulization: You may consider using albuterol nebulizers if needed for wheezing.

Steroids: Administration of corticosteroids is believed to help prevent or control the late-phase reaction. Loading dose is Solumedrol 125 mg followed by 40 mg every 6 hours while in the ER or CDU. Upon discharge they should be given a prescription for prednisone.

Late phase reactions can occur 4-6 hours after the initial reaction and can be as severe as or worse than the original reaction.

Patients should be given a prescription for at least 2 autoinjectable epinephrine doses (eg, 2 EpiPens ) and instructed in their proper use. Instruct Patients to carry them at all times or to keep one at home and one in their purse or at work.

Patients should be informed of the potential for future anaphylactic reactions, and what medications to use when to call 911 or go to the nearest emergency department (even if feeling better after the epinephrine).