From the Guidelines
The initial treatment for suspected anaphylactic shock is immediate administration of epinephrine (adrenaline) via intramuscular injection, typically 0.3-0.5 mg (0.3-0.5 mL of 1:1000 concentration) for adults or 0.15 mg for children under 30 kg, injected into the mid-outer thigh, as recommended by the most recent guidelines 1. This should be given as soon as anaphylaxis is suspected, without waiting for complete symptom development. The rationale behind this recommendation is based on the pathophysiological effects of epinephrine, which include increased vasoconstriction, increased inotropy and chronotropy, bronchodilation, and decreased release of mediators of inflammation from mast cells and basophils, as outlined in earlier studies 1. After epinephrine administration, the patient should be placed in a supine position with legs elevated unless respiratory distress makes this impossible. Supplemental oxygen should be provided, and intravenous access established for fluid resuscitation with normal saline (typically 1-2 liters for adults) to counter vascular collapse. Additional supportive measures include administering antihistamines (such as diphenhydramine 25-50 mg IV/IM) and corticosteroids (such as methylprednisolone 125 mg IV), though these are secondary to epinephrine, as noted in various guidelines 1. Epinephrine is the cornerstone of treatment because it rapidly reverses the life-threatening pathophysiological effects of anaphylaxis. The dose may be repeated every 5-15 minutes if symptoms persist or worsen, as suggested by recent and high-quality studies 1. It's crucial to follow the most recent and highest quality guidelines for the management of anaphylaxis to ensure the best outcomes in terms of morbidity, mortality, and quality of life.
From the FDA Drug Label
Emergency treatment of allergic reactions (Type I), including anaphylaxis, which may result from allergic reactions to insect stings, biting insects, foods, drugs, sera, diagnostic testing substances and other allergens, as well as idiopathic anaphylaxis or exercise-induced anaphylaxis. For suspected anaphylactic shock, order epinephrine (IM) stat. This is the initial treatment for anaphylaxis, as indicated in the drug label for epinephrine (IM) 2.
- Key treatment: Epinephrine (IM)
- Administration route: Intramuscular (IM)
- Timing: Stat (immediately)
From the Research
Initial Treatment for Suspected Anaphylactic Shock
The initial treatment for suspected anaphylactic shock involves administering epinephrine (adrenaline) immediately. Key points to consider include:
- Epinephrine is the drug of choice for anaphylaxis and should be administered as soon as the diagnosis is suspected 3, 4, 5, 6.
- The recommended initial dose for adults is 0.3-0.5 mg, injected intramuscularly in the anterolateral aspect of the mid-thigh 3, 4.
- For children, the dose is 0.01 mg/kg, given in the lateral thigh 4.
- Intravenous epinephrine may be used in patients in shock, either as a bolus or infusion, along with fluid resuscitation 5.
Additional Considerations
Other important considerations in the treatment of anaphylactic shock include:
- Airway obstruction must be recognized, and early intubation may be necessary 5.
- Fluid resuscitation with Ringer's lactate solution or other intravenous fluids should be initiated to treat intravascular volume depletion 7, 6.
- Antihistamines and corticosteroids may be given as second-line medications, but should never be given in lieu of, or prior to, epinephrine 4, 6.
- Patients should be observed closely after epinephrine administration for potential complications, such as myocardial ischemia 7.