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Epinephrine Auto-Injector

Category: Pharmacology Sources: raw/supplemental/emt-b-pharmacology.md Last updated: 2026-04-03

Overview

Epinephrine is the primary treatment for anaphylaxis — a severe, life-threatening allergic reaction. It works by causing vasoconstriction (raises BP), bronchodilation (opens airways), and reducing urticaria and angioedema. In anaphylaxis, there are no absolute contraindications — the benefit always outweighs the risk. Trade names: EpiPen, Auvi-Q.

Key Points

  • Indications: Severe allergic reaction (anaphylaxis) with signs of systemic involvement:
  • Airway: stridor, throat tightness, hoarseness, angioedema (swelling of lips, tongue, throat)
  • Breathing: wheezing, bronchospasm, difficulty breathing
  • Circulation: hypotension, tachycardia, signs of shock
  • Skin: urticaria (hives), flushing, diffuse itching — alone is not sufficient; must have systemic involvement
  • Doses:
  • Adult: 0.3 mg IM (EpiPen) — typically patients ≥30 kg or adults
  • Pediatric: 0.15 mg IM (EpiPen Jr) — typically patients <30 kg
  • Route: Intramuscular (IM) injection into the lateral thigh (vastus lateralis). Can be administered through clothing in an emergency.
  • Contraindications: None in true anaphylaxis. Cardiac risk of epinephrine is always outweighed by the risk of anaphylaxis progression.
  • Repeat dose: May repeat per protocol if symptoms do not improve — typically once, after 5–10 minutes, if authorized.
  • Authorization: Standing order or online medical direction.

Assessment Relevance

Anaphylaxis recognition is driven by history-taking and primary-assessment. Look for: - Known allergen exposure (bee sting, food, medication, latex) — found in SAMPLE history (Allergies section) - Rapid onset (seconds to minutes after exposure) - Multi-system involvement: skin + either airway or cardiovascular = anaphylaxis until proven otherwise - Patient may self-report "my throat is closing," "I can't breathe," "I feel like I'm going to die"

During primary-assessment: - Airway: stridor, hoarseness, inability to speak in full sentences - Breathing: wheezing audible or on auscultation - Circulation: weak/rapid pulse, hypotension, pale/cool/diaphoretic skin - LOC may be altered due to hypoperfusion

Key distinction: mild allergic reaction (localized hives only) does not require epinephrine. Systemic reaction (airway, breathing, or cardiovascular involvement) requires immediate epinephrine.

Procedures

  1. Identify anaphylaxis during primary-assessment and history-taking.
  2. Confirm criteria: known or suspected allergen exposure + systemic signs.
  3. Obtain authorization (standing order or contact medical control).
  4. Select correct auto-injector (adult 0.3 mg or pediatric 0.15 mg based on weight).
  5. Remove safety cap from auto-injector.
  6. Place dominant-hand grip on auto-injector; non-dominant hand steadies the thigh.
  7. Press firmly against the lateral thigh until click; hold for 10 seconds.
  8. Remove, rub site for 10 seconds.
  9. Note time of administration.
  10. Reassess within 5 minutes — airway, breathing, circulation, skin.
  11. Repeat dose if no improvement and authorized by protocol.
  12. Dispose of used auto-injector in sharps container; do not re-cap.
  13. Document: time, dose, site, authorization, patient response.

NM Protocol Notes

  • NM EMT-B scope includes epinephrine auto-injector administration for anaphylaxis. Check current NM EMS Bureau protocol for standing order criteria.
  • NM may authorize a second dose if the first dose does not improve symptoms — confirm current protocol.
  • Epinephrine does not replace transport — anaphylaxis patients need ALS evaluation and possible hospital admission for biphasic reaction monitoring (recurrence 2–8 hours later).
  • In San Juan County rural settings, ALS intercept should be requested early; epinephrine buys time but does not end the emergency.

NREMT Relevance

Epinephrine auto-injector is a standalone psychomotor skill station on the NREMT exam and a high-frequency cognitive (written) topic. Examiners look for: - Correct indications — systemic involvement required, not just hives - Correct dose selection (adult vs pediatric by weight) - Correct injection site — lateral thigh - Holding auto-injector in place for 10 seconds - Reassessment within 5 minutes - Recognizing when to repeat

Common miss: administering to a patient with only localized urticaria (hives) without systemic involvement — epinephrine is not indicated. The scenario will test whether you recognize the difference.

  • primary-assessment — airway and breathing compromise identified here is the primary trigger
  • history-taking — allergen exposure and allergy history in SAMPLE drives the decision
  • reassessment — reassess within 5 minutes; repeat dose consideration
  • oxygen — O2 administration co-indicated in anaphylaxis with respiratory compromise
  • oxygen-administration — procedure for O2 delivery in the anaphylaxis patient

Sources

  • raw/supplemental/emt-b-pharmacology.md — Epinephrine Auto-Injector section and General Medication Administration Rules