From the Guidelines
The recommended dose of epinephrine for anaphylaxis in adults is 0.2 to 0.5 mg (1:1000) intramuscularly, to be repeated every 5 to 15 min as needed. This dose is based on the most recent guidelines from the American Heart Association, which emphasize the importance of early administration of epinephrine in patients with signs of a systemic allergic reaction, especially hypotension, airway swelling, or difficulty breathing 1. The intramuscular route is preferred over subcutaneous injection because it provides a more rapid increase in plasma and tissue concentrations of epinephrine.
Some key points to consider when administering epinephrine for anaphylaxis include:
- The dose can be repeated every 5-15 minutes if symptoms persist or worsen
- Auto-injectors (such as EpiPen or Auvi-Q) are available in 0.3 mg doses for adults weighing over 30 kg
- After administering epinephrine, the patient should seek immediate medical attention even if symptoms improve, as anaphylaxis can have a biphasic response with symptoms returning hours later
- Epinephrine works by constricting blood vessels to increase blood pressure, relaxing airway muscles to improve breathing, and reducing hives and swelling
- It is the first-line treatment for anaphylaxis because it addresses multiple physiological effects of this severe allergic reaction simultaneously
It's also important to note that in patients with anaphylactic shock, close hemodynamic monitoring is recommended, and immediate referral to a health professional with expertise in advanced airway placement, including surgical airway management, is recommended 1. Additionally, when an IV line is in place, it is reasonable to consider the IV route for epinephrine in anaphylactic shock, at a dose of 0.05 to 0.1 mg (0.1 mg/mL, aka 1:10 000) 1.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Anaphylaxis: Adults and Children 30 kg (66 lbs) or more: 0.3 to 0.5 mg (0.3 to 0.5 mL) intramuscularly or subcutaneously into anterolateral aspect of the thigh every 5 to 10 minutes as necessary
The recommended dose of epinephrine for anaphylaxis in adults is 0.3 to 0.5 mg (0.3 to 0.5 mL) intramuscularly or subcutaneously into the anterolateral aspect of the thigh, repeated every 5 to 10 minutes as necessary 2.
From the Research
Epinephrine Dosing in Adult Anaphylaxis
- The recommended dose of epinephrine for anaphylaxis in adults is 0.3-0.5 mg, injected intramuscularly in the anterolateral aspect of the mid-thigh 3, 4.
- This dose is based on the need for rapid action to prevent and relieve upper and lower airway obstruction and shock 3.
- The intramuscular route is preferred over subcutaneous or intravenous administration due to its more satisfactory therapeutic window and lower risk of adverse effects 3, 5.
Administration and Education
- Education of patients and healthcare providers on the proper use of epinephrine auto-injectors is crucial for effective management of anaphylaxis 4, 6.
- Strategies to improve education and access to appropriate drugs, such as labeled "anaphylaxis boxes" on resuscitation trolleys, may help reduce confusion and errors in epinephrine administration 6.
- Prefilled and labeled intramuscularly dosed epinephrine syringes can help distinguish them from intravenously dosed syringes and reduce the risk of iatrogenic overdose 5.
Special Considerations
- In obese patients, the intramuscular route and lateral thigh site may be superior, but the needle length of standard epinephrine auto-injectors may be insufficient 7.
- In patients weighing less than 15 kg, the dose of epinephrine auto-injectors may exceed the recommended dose, and alternative devices with shorter needles and lower doses may be necessary 7.
- Further research on epinephrine pharmacodynamics in children and adults with anaphylaxis is needed to optimize dosing and delivery 7.