What is the proper administration of EpiPen (epinephrine) in an anaphylactic reaction?

EpiPen Administration in Anaphylactic Reaction

Inject epinephrine 0.3 mg (adult) or 0.15 mg (child <30 kg) intramuscularly into the anterolateral thigh (vastus lateralis) immediately upon recognition of anaphylaxis, and repeat every 5 minutes as needed until symptoms resolve. 1, 2

Immediate Recognition and Action

• Administer epinephrine as first-line treatment without delay – delaying epinephrine is associated with increased mortality and morbidity 1, 3
• Do not wait for complete diagnostic certainty; if anaphylaxis is suspected, give epinephrine immediately 3
• There is no absolute contraindication to epinephrine in anaphylaxis, even in elderly patients or those with cardiac disease 2, 3

Proper Administration Technique

Site Selection

• Inject into the anterolateral thigh (vastus lateralis muscle) – this is the only recommended site 1, 4
• Intramuscular injection in the thigh achieves peak plasma concentrations in 8±2 minutes, compared to 34±14 minutes with subcutaneous deltoid injection 1, 2
• The EpiPen can be administered through clothing directly into the lateral thigh 1, 2

Critical Sites to Avoid

• Never inject into the buttock – this may not provide effective treatment and has been associated with Clostridial infections (gas gangrene) 4
• Never inject into digits, hands, or feet – epinephrine's vasoconstriction can cause tissue necrosis and loss of blood flow 4
• Do not inject into the deltoid muscle – smaller muscle mass results in less reliable absorption 4

Dosing Protocol

Standard Doses

• Adults and children ≥30 kg (66 lbs): 0.3 mg (EpiPen) 1, 2
• Children 15-30 kg (33-66 lbs): 0.15 mg (EpiPen Jr) 1, 2
• Maximum single dose: 0.5 mg for adults, regardless of body weight 2

Repeat Dosing

• Repeat every 5 minutes if symptoms persist, worsen, or recur 1, 2
• There is no maximum number of doses – continue until symptoms resolve 2
• Approximately 10-28% of patients require a second dose, and some require more 2
• Do not stop at one dose prematurely – fatalities are associated with delayed or inadequate epinephrine, not with giving multiple doses 2

Concurrent Management Steps

After administering epinephrine:

1. Call 911 immediately or activate emergency medical services 2
2. Position patient supine with legs elevated (unless respiratory distress prevents this) 1, 2
3. Never allow the patient to stand or walk – this increases mortality risk 2
4. Administer supplemental oxygen at 6-8 L/min if available 1
5. Establish IV access and give normal saline bolus (1-2 L for adults, up to 30 mL/kg in first hour for children) if hypotension persists 1

When to Escalate Beyond Intramuscular Epinephrine

Indications for IV Epinephrine

• Refractory shock despite multiple IM doses and fluid resuscitation 1, 5
• Cardiac arrest from anaphylaxis 1
• Patient in a monitored hospital setting with profound hypotension 1

IV Dosing (Hospital Setting Only)

• Bolus: 0.05-0.1 mg (50-100 mcg) of 1:10,000 solution IV slowly 1
• Infusion: 1-4 mcg/min, titrating up to maximum 10 mcg/min based on response 1, 2
• Critical warning: IV epinephrine carries significant risk of dilution/dosing errors and cardiac arrhythmias – several fatalities have been attributed to injudicious IV use 1

Common Pitfalls and How to Avoid Them

Concentration Confusion

• IM injection: Always use 1:1000 (1 mg/mL) concentration 1, 2, 3
• IV injection: Only use 1:10,000 (0.1 mg/mL) concentration 1, 3
• Confusing these concentrations can result in 10-fold dosing errors and potentially fatal outcomes 3

Delayed Administration

• Do not wait for antihistamines or corticosteroids – these are not substitutes for epinephrine and should never delay its administration 1, 3
• Do not rely on inhalers alone for respiratory symptoms 3
• Skin signs may be absent in 10% of anaphylaxis cases – do not wait for hives to appear 2

Premature Cessation

• Do not assume one dose is sufficient – monitor continuously and repeat as needed 2
• Symptoms can recur after initial improvement (biphasic reactions occur in some patients) 1

Post-Administration Requirements

• All patients must be transported to the emergency department via EMS for observation, even if symptoms completely resolve 1, 2
• Observation should continue in a setting capable of managing anaphylaxis until symptoms have fully resolved 1
• Prescribe two epinephrine autoinjectors for home use at discharge 2
• Provide education on trigger avoidance, symptom recognition, and proper autoinjector use 1
• Refer to an allergist for comprehensive evaluation 1

Special Populations

Patients with Cardiovascular Disease

• Still administer epinephrine – the risk of death from untreated anaphylaxis far exceeds the risk of epinephrine-related cardiac effects 2, 3, 4
• Epinephrine may precipitate angina or arrhythmias in these patients, but this does not contraindicate its use in life-threatening anaphylaxis 4

Patients with Asthma

• These patients are at higher risk of fatal anaphylaxis and require particularly prompt epinephrine administration 3
• Lower threshold for epinephrine use in asthmatic patients with allergic reactions 3

Pregnancy

• Administer epinephrine despite pregnancy – maternal and fetal survival depends on adequate treatment 4