Skip to content

Epinephrine Auto-Injector

Category: Pharmacology Sources: raw/supplemental/emt-b-pharmacology.md; UCLA EMT Ultimate Study Guide (2026) Last updated: 2026-05-06

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.

NREMT Differentiators

Key Facts — Epinephrine Auto-Injector

Detail Value
Concentration 1:1,000 (1 mg/mL) — IM only
Adult dose 0.3 mg IM
Pediatric dose 0.15 mg IM (EpiPen Jr)
Weight threshold Adult ≥30 kg; pediatric <30 kg
Injection site Lateral thigh (vastus lateralis)
Through clothing? YES
Hold time 10 seconds
Contraindications in anaphylaxis NONE — benefit always outweighs risk
Can repeat? Yes, once, after 5–15 minutes if symptoms persist

KEY DIFFERENTIATOR — No Contraindications: In true anaphylaxis, there are no absolute contraindications to epinephrine. Not pregnancy, not elderly, not cardiac history, not nothing. Failing to give epinephrine in anaphylaxis is worse than any side effect. This is THE single most important epinephrine fact.

NREMT TRAP — 1:1,000 vs 1:10,000: Auto-injector (IM) = 1:1,000. IV use (ALS only) = 1:10,000. Same drug, different concentrations, different routes. The NREMT tests this distinction. Never give 1:1,000 IV.

Anaphylaxis Epinephrine Decision

Systemic involvement present?
 (airway: wheeze/stridor OR cardiovascular: hypotension/tachycardia/syncope)
       |
      YES → Give epinephrine IM NOW
       |
       NO (hives only) → Do NOT give epinephrine; monitor for progression

KEY DIFFERENTIATOR — Hives Alone: Localized urticaria (hives) without systemic involvement = allergic reaction, not anaphylaxis. No epinephrine. Monitor closely for progression. The NREMT will put hives in the scenario to see if you give epi inappropriately.

  • six-rights — Right Dose is critical: adult 0.3 mg vs. pediatric 0.15 mg; verify before administration
  • 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