Emergency drugs act within minutes on a problem that is killing the client now. Know the target of each one:

• Epinephrine in anaphylaxis — alpha-1: vasoconstriction reverses hypotension and mucosal swelling; beta-1: stronger heartbeat; beta-2: bronchodilation and stops further mast cell mediator release. It is the only drug that treats all of these at once.
• Antihistamines block H₁ (and H₂) receptors — relieve itching and hives only. Corticosteroids act over hours — they do not treat airway swelling or shock.
• Aspirin irreversibly blocks platelet cyclooxygenase → less thromboxane A₂ → less clot growth in acute coronary syndrome (ACS).
• Nitroglycerin releases nitric oxide → venodilation (↓preload) and coronary dilation.
• Loop diuretics (furosemide) — block the Na-K-2Cl pump in the loop of Henle; IV doses also cause early venodilation.
• Benzodiazepines (lorazepam, midazolam, diazepam) — enhance GABA-A, stopping seizures.
• Dextrose supplies glucose directly; glucagon releases liver glycogen (needs glycogen stores).
• Atropine blocks muscarinic receptors → faster sinus rate and AV conduction. Adenosine briefly blocks the AV node. Amiodarone and lidocaine suppress ventricular dysrhythmias.
• Calcium stabilizes the cardiac cell membrane in hyperkalemia; insulin and beta-2 agonists shift potassium into cells. Magnesium sulfate stabilizes the membrane in torsades de pointes and prevents eclamptic seizures.

Anaphylaxis — epinephrine first

Other emergencies (adult doses; follow local protocol)

• Epinephrine in anaphylaxis has no absolute contraindication — including pregnancy, older age, and heart disease. The risk of not giving it is greater.
• Beta blockers can make anaphylaxis more severe and blunt the response to epinephrine → glucagon. ACE inhibitors may worsen anaphylaxis severity.
• Nitrates + PDE-5 inhibitors (sildenafil, vardenafil, tadalafil, riociguat): profound hypotension — contraindicated.
• Aspirin: active bleeding, true aspirin allergy.
• Adenosine: effect reduced by theophylline and caffeine, increased by dipyridamole and carbamazepine; lower dose (3 mg) through a central line or after heart transplant; caution in asthma; contraindicated in second- or third-degree AV block or sick sinus syndrome without a pacemaker; not for irregular or polymorphic wide-complex tachycardia.
• Atropine: may not work in Mobitz II or complete heart block (prepare pacing); avoid relying on it after heart transplant.
• Glucagon: does not work when glycogen is depleted (starvation, heavy alcohol use, adrenal insufficiency).
• Calcium with digoxin: increased dysrhythmia risk — give slowly with monitoring; never mix calcium with sodium bicarbonate or phosphate (precipitate).
• Benzodiazepines + opioids or alcohol: additive respiratory depression (boxed warning on benzodiazepines and opioids).
• Pregnancy: in true emergencies the mother is treated first; magnesium is the eclampsia drug of choice.

Listed in priority order.

1. Anaphylaxis: give IM epinephrine first — before oxygen, IV access, antihistamines, or waiting for vital signs. Stop the trigger (e.g., infusion), call for help.
2. Airway and breathing — high-flow oxygen; prepare for intubation with stridor, hoarseness, or tongue swelling; position supine with legs raised (sitting if breathing is hard; do not stand the client up suddenly).
3. Circulation — two large-bore IVs, fluid boluses, continuous ECG, BP, SpO₂ every 5 minutes; reassess after every emergency drug (ABCs, vital signs, rhythm, level of consciousness, glucose).
4. Dose safety
   • Confirm route and concentration: IM 1 mg/mL for anaphylaxis; 0.1 mg/mL (1 mg in 10 mL) for IV use in cardiac arrest
   • Closed-loop communication during codes; record time of every dose
   • Adenosine: large proximal vein, rapid push with immediate 20 mL saline flush; warn the client about the brief feeling of doom
5. Drug-specific checks
   • Nitroglycerin: BP before each dose; client sitting or lying
   • Benzodiazepines: RR, SpO₂, sedation; bag-valve mask ready
   • Dextrose: check IV patency (vesicant); recheck glucose in 15 minutes
   • Glucagon: turn the client on the side (vomiting)
   • Insulin–dextrose: glucose hourly for several hours
   • Magnesium: reflexes, RR, urine output; calcium gluconate at bedside
6. Observe after anaphylaxis for a biphasic reaction (hours later); longer observation after severe reactions or repeated epinephrine doses. Tryptase may support the diagnosis but never delays treatment.

• Carry two epinephrine devices at all times; use at the first sign of a serious reaction (breathing trouble, throat tightness, faintness, widespread hives with vomiting), then call emergency services
• Auto-injector: inject into the outer thigh, through clothing if needed; hold per device instructions; a second dose may be needed after 5–15 minutes
• Epinephrine first; antihistamines never replace it; go to the hospital after every use
• Check device expiry dates; store at room temperature; teach family, school, and coworkers; wear medical identification
• Tell prescribers about beta blocker use if allergies are severe
• Nitroglycerin: sit down, dissolve under the tongue; if pain is not better 5 minutes after the first dose, call emergency services; keep tablets in the original dark glass bottle
• Hypoglycemia: family learns to give glucagon and to place the person on their side

• Anaphylaxis: IM epinephrine 0.01 mg/kg (max 0.5 mg adult, 0.3 mg child) in the mid-outer thigh — first, immediately
• No absolute contraindication to epinephrine in anaphylaxis
• Antihistamines and corticosteroids are adjuncts only; they do not treat airway obstruction or shock
• Beta blocker + refractory anaphylaxis → glucagon
• Carry two devices; watch for a biphasic reaction
• ACS: aspirin chewed; nitroglycerin 0.4 mg SL every 5 minutes × 3; no nitrates after PDE-5 inhibitors
• Status epilepticus ≥ 5 minutes → IV lorazepam or IM midazolam
• Unconscious hypoglycemia → IV dextrose or glucagon; nothing by mouth
• Bradycardia → atropine 1 mg, max 3 mg; SVT → adenosine 6 mg then 12 mg, rapid push + flush
• Hyperkalemia with ECG changes → calcium first, then insulin + dextrose
• Magnesium toxicity → calcium gluconate