What is the standard dosing (sig) for EpiPen (epinephrine) administration in adults and children?

EpiPen Dosing (Sig)

For adults and children ≥25 kg (55 lbs): EpiPen 0.3 mg intramuscularly into the anterolateral thigh; may repeat every 5-15 minutes as needed. For children 10-25 kg: EpiPen Jr 0.15 mg intramuscularly into the anterolateral thigh; may repeat every 5-15 minutes as needed. 1, 2

Weight-Based Dosing Guidelines

Children 10-25 kg (22-55 lbs)

• EpiPen Jr 0.15 mg intramuscularly into the anterolateral thigh 1, 2
• This provides approximately 0.01 mg/kg for a child at the midpoint of this weight range 1
• May repeat every 5-15 minutes if symptoms persist or recur 1, 2

Children ≥25 kg and Adults

• EpiPen 0.3 mg intramuscularly into the anterolateral thigh 1, 2
• The 25 kg threshold is critical because the 0.15 mg dose would provide only 0.006 mg/kg at this weight, representing significant underdosing 3
• May repeat every 5-15 minutes if symptoms persist or recur 1, 2

Adults ≥30 kg (FDA labeling)

• 0.3 to 0.5 mg intramuscularly into the anterolateral thigh 2
• Maximum 0.5 mg per injection 2
• Repeat every 5-10 minutes as necessary based on clinical response 2

Administration Technique

Injection Site and Method

• Inject into the anterolateral aspect of the mid-thigh (vastus lateralis muscle) at a 90-degree angle 1, 3, 2
• Can be administered through clothing if necessary during emergencies 3, 2
• This site achieves peak plasma concentrations in 8±2 minutes, compared to 34±14 minutes with subcutaneous deltoid injection 1, 3

Critical Technical Points

• Hold the leg firmly in place when administering to children to minimize injection-related injury 2
• Use a needle at least 1/2 to 5/8 inch long to ensure intramuscular delivery 2
• Do not inject repeatedly at the same site due to risk of tissue necrosis from vasoconstriction 2

Repeat Dosing Protocol

• Repeat every 5-15 minutes if symptoms persist, recur, or progress 1, 2
• The interval can be liberalized for more frequent injections if clinically indicated 1
• Monitor for severity of allergic reaction and potential cardiac effects between doses 2
• Patients requiring multiple doses have higher risk of biphasic reactions 3

When to Administer

Immediate Indications

• Respiratory symptoms: difficulty breathing, wheezing, throat tightness, stridor 4
• Cardiovascular symptoms: hypotension, dizziness, fainting, loss of consciousness 4
• Skin manifestations with systemic symptoms: widespread hives with respiratory or cardiovascular involvement 4
• Known allergen exposure in someone with previous anaphylaxis, even if symptoms are initially mild 4

Decision Algorithm

• If there has been exposure to a known allergen trigger AND previous anaphylaxis to this trigger → use EpiPen immediately 4
• If any respiratory, cardiovascular, or multi-system symptoms are present → use EpiPen immediately 4
• When in doubt, use the EpiPen - the risk of untreated anaphylaxis far exceeds the risk of appropriate epinephrine use 4, 2

Common Pitfalls to Avoid

• Never delay administration to wait for antihistamines or other medications - epinephrine is first-line treatment and delays are associated with increased mortality 4, 3, 5
• Never use subcutaneous route - intramuscular injection in the thigh is superior and provides more rapid absorption 1, 3
• Never inject into the deltoid for initial treatment - the anterolateral thigh provides superior absorption 1, 3
• Do not rely on antihistamines or inhalers as substitutes for epinephrine in anaphylaxis 4
• Do not assume mild symptoms will remain mild - anaphylaxis can progress rapidly and unpredictably 4

Special Populations

Infants <10 kg

• No autoinjector is specifically designed for this weight range 1
• In life-threatening emergencies when no other option exists, EpiPen Jr (0.15 mg) should be used despite representing an overdose 6
• The risk of death from untreated anaphylaxis far exceeds the risk of epinephrine overdose 6

Patients with Cardiovascular Disease

• No absolute contraindication to epinephrine in anaphylaxis 1, 4, 3
• The risk of death from untreated anaphylaxis exceeds any risk from epinephrine 1, 4

Post-Administration Care

• All patients who receive epinephrine must proceed to an emergency facility for observation 1
• Observe for 4-6 hours minimum; longer observation or admission for severe/refractory symptoms 1
• Discharge with anaphylaxis emergency action plan and two epinephrine autoinjectors 1
• Monitor for biphasic reactions, which can occur up to 72 hours later (mean 11 hours) 3