EpiPen Dosing for a 17-Year-Old
A 17-year-old at risk of anaphylaxis should be prescribed the adult EpiPen 0.3 mg dose (or up to 0.5 mg if using standard epinephrine ampules), administered intramuscularly into the anterolateral thigh, with a second dose available for repeat administration every 5-15 minutes if symptoms persist. 1, 2, 3
Specific Dosing Recommendations
For teenagers and adults weighing ≥30 kg (66 lbs):
- Standard dose: 0.3 to 0.5 mg of epinephrine (1:1000 concentration) 1, 2, 3
- Route: Intramuscular injection into the mid-outer thigh (vastus lateralis muscle) 1, 2
- Timing: Repeat every 5-15 minutes as needed based on clinical response 1, 2, 3
At 17 years old, this patient is well beyond the 25 kg (55 lb) threshold where the transition from junior (0.15 mg) to adult (0.3 mg) EpiPen occurs, making the adult formulation clearly appropriate. 1, 4
Administration Technique
Critical technical points:
- Inject into the anterolateral aspect of the mid-thigh (vastus lateralis muscle) - this route achieves peak plasma concentrations in 8±2 minutes compared to 34±14 minutes with subcutaneous deltoid injection 1, 4
- Never inject into buttocks, digits, hands, or feet 3
- The patient should be positioned lying down with legs elevated, or in a position of comfort if experiencing respiratory distress 1
- Do not allow the patient to stand, walk, or run after injection 1
When to Administer
Inject epinephrine immediately when anaphylaxis is recognized, defined by: 1
- Acute onset of skin/mucosal symptoms (hives, swelling, flushing) PLUS respiratory compromise (wheeze, stridor, dyspnea) OR hypotension/shock
- Two or more body systems involved (skin, respiratory, cardiovascular, gastrointestinal) after allergen exposure
- Known allergen exposure followed by hypotension
Common pitfall: Delayed administration is associated with fatal outcomes, particularly in adolescents with concomitant asthma. 1, 4, 5 Never delay epinephrine to give antihistamines or corticosteroids first - these are second-line therapies only. 1, 4, 5
Prescription Details
Prescribe TWO epinephrine autoinjectors - approximately 6-19% of patients require a second dose, and patients at higher risk for biphasic reactions (those requiring multiple doses) need immediate access to additional medication. 2, 4, 6
High-risk features in adolescents that warrant particular vigilance: 1
- Concomitant asthma (especially if severe or poorly controlled)
- History of previous severe reactions
- Known food allergies (particularly peanuts, tree nuts, shellfish)
Safety Considerations
There are no absolute contraindications to epinephrine use in anaphylaxis. 2, 4 Even patients with cardiac disease, hypertension, or other comorbidities should receive epinephrine when anaphylaxis occurs, as the benefits far outweigh risks. 2, 3
Expected transient side effects include: 1, 2
- Pallor, tremor, anxiety
- Palpitations, headache
- Nausea (with higher doses)
These effects cannot be dissociated from therapeutic effects and resolve quickly. 1, 4
Follow-Up After Administration
- Call 911 immediately and transport to emergency department, preferably by EMS 1, 2
- Observation periods must extend several hours due to risk of biphasic reactions (mean onset 11 hours, can occur up to 72 hours later) 4
- Additional treatments in hospital may include: supplemental oxygen, IV fluids, inhaled albuterol for persistent bronchospasm, H1/H2 antihistamines, and corticosteroids 1