Racemic and Nebulized Epinephrine

Emergency & Prehospital

• Moderate to severe croup (Westley score 3 or higher, or stridor at rest): this is where nebulized epinephrine earns its place, stacked on a corticosteroid. The Canadian Paediatric Society (CPS) recommends it for moderate to severe croup.
• Upper-airway edema with stridor after extubation (off-label): the evidence reviewed covers adults, and children were studied too. Give it with corticosteroids. Reintubate without delay if respiratory failure develops.

ED / ICU / Transport

• Post-extubation stridor in children (off-label): researchers studied nebulized L-epinephrine in children with a Westley score of 4 or higher after extubation.
• Adult upper-airway obstruction from edema (off-label): adjunct only, per protocol. The adult evidence reviewed is observational. It is not trial data. See epinephrine IM for the anaphylaxis airway adjunct.

Other Uses

• Labeled use of racepinephrine (US OTC label): the label covers temporary relief of wheezing in mild intermittent asthma, in adults and children 4 years and older. Croup is not on that label.
• Not a first-line treatment for typical croup: CPS says antibiotics and short-acting beta-2 agonists are rarely indicated in typical croup.

Doses vary by protocol; follow local protocols and medical direction.

Available Forms

• Racemic epinephrine 2.25% (racepinephrine): 0.5 mL unit-dose vial, each containing 11.25 mg racepinephrine base (13.5 mg as the hydrochloride salt). 30 vials per carton (US product, Nephron S2).
• L-epinephrine 1 mg/mL (1:1,000): 1 mL single-dose vial (1 mg). Nebulizing it is off-label. The US adrenaline label covers anaphylaxis and septic shock only.

Adult Dosing

Pediatric Dosing

See weight-based dosing and the Broselow tape. Corticosteroid dosing: see dexamethasone.

Preparation & Administration

• Dilution: use the racemic 0.5 mL vial as supplied. The US label says to add the whole vial to the nebulizer. If your protocol adds saline, the protocol sets the volume.
• Route: inhalation only. Never inject, push IV or add to an IV line.
• Nebulizer: use the device your protocol names. In the racemic comparison cited in the 2026 review, nebulizer choice did not change the effect.
• Observation clock: write down when the nebulization ends. That is when the observation clock starts.

Contraindications

• Monoamine oxidase inhibitor (MAOI) use, or within 2 weeks of stopping one (US OTC racepinephrine label).
• Cloudy, discolored or precipitated solution: the label says don't use it.
• The sources reviewed name no absolute contraindication in life-threatening airway obstruction.

Precautions

• Heart disease, high blood pressure, diabetes, thyroid disease: the label says to ask a doctor first. In an emergency, you give the drug and monitor heart rate, BP and ECG.
• Seizures, narrow-angle glaucoma, urinary retention from prostate enlargement: the label lists these as cautions.
• Bacterial tracheitis and epiglottitis: high fever, toxic appearance, drooling or dysphagia point you toward other diagnoses. CPS notes poor response to nebulized epinephrine in bacterial tracheitis.

Hold / Reassess If

• Rapid heartbeat, tremor, nervousness or seizure (label stop criteria): stop further doses and reassess.
• Rising blood pressure or heart rate: the label warns both may go up. Check after each dose.
• No change in Westley score at 30 min, or worsening stridor: escalate airway care per protocol.

Common

• Pallor, restlessness, agitation, tremor and nervousness (US label).
• Expect tachycardia. It is a sympathomimetic effect. In the post-extubation trial (da Silva 2012), heart rate and BP rose modestly at higher doses, and BP rose significantly at 5 mL.
• Transient rise in blood pressure, most clearly with the 5 mL L-epinephrine dose (randomized trial in children).

Serious / Life-Threatening

• Hypertension, tachyarrhythmia or ischemia: the label warns of a higher risk of heart attack or stroke, and either can be fatal. Watch for chest pain, ectopy and ST change. Stop further doses.
• Cardiac effects with repeated doses: the review says patients with frequent treatments need monitoring for adverse cardiac effects. None of the Cochrane trials looked for or reported adverse-effect data, so safety was not assessed.

Overdose & Toxicity Management

• Signs: severe tachycardia, hypertension, arrhythmia, tremor and agitation (sympathomimetic excess).
• Immediate management: stop further doses; airway, breathing and circulation; continuous monitoring; 12-lead ECG; treat arrhythmia per ACLS or PALS.
• Specific treatment: the sources reviewed name no specific antidote. Call Poison Help at 1-800-222-1222 for antidote and dosing advice.

Clinically Significant Interactions

• Pediatrics: CPS says one standard dose fits every age and weight. The weight-based dose is also in wide use, and the dose tables sit above. The US OTC asthma label covers ages 4 and older. Under 4, it says to ask a doctor first. Croup use is off-label at any age. Under 10 kg is where the two approaches pull furthest apart.
• Neonates: the sources reviewed establish nothing here. This page does not cover neonates.
• Pregnancy: the sources reviewed establish no specific adjustment. The decision rests with medical direction.
• Lactation: the sources reviewed establish no specific adjustment.
• Older Adults: the cardiac precautions above apply, most of all to heart disease and high blood pressure. No separate dose is established.
• Renal Impairment: the sources reviewed establish no specific adjustment.
• Hepatic Impairment: no liver-specific adjustment is established in the sources reviewed.
• Obesity / Dosing Weight: pediatric doses run on measured body weight. The caps above still apply.

• Scope: it varies by state and agency protocol. Racemic epinephrine is hard to get in many regions, and in Canada. That is why L-epinephrine is the usual substitute (2026 review; CPS).
• Storage & Stability: the US racepinephrine label says store at 2–25°C (36–77°F). Protect it from light and freezing. Don't use it if it is brown, cloudy or has precipitate.
• Carried Concentration: label the racemic 2.25% and the 1 mg/mL vial clearly. Don't let the 1 mg/mL vial pass for the 0.1 mg/mL arrest syringe.
• Infusions in Transport: not applicable. This is nebulized use only.
• Handoff Essentials: time and dose of each nebulization in mg and mL, product, Westley score before and after, the time observation started, and any recurrence.

Mechanism of Action

• Alpha-adrenergic effect: vasoconstriction shrinks laryngeal mucosal edema. That edema is the target in croup.
• Beta-adrenergic effect: bronchodilation and cardiac effects. Tachycardia and BP rise are the main adverse effects.
• Racemic mixture: it holds both D- and L-epinephrine. L-epinephrine alone is the active isomer, and it did just as well in the comparisons above.

Pharmacokinetics

• Half-life: the sources reviewed do not establish one.
• Metabolism: it follows systemic epinephrine. The sources reviewed do not characterize it.
• Elimination: the sources reviewed do not establish it.

Generic Name

Racepinephrine hydrochloride (racemic epinephrine) 2.25% inhalation solution; epinephrine (L-epinephrine) 1 mg/mL (1:1,000) injection, used off-label for nebulization

Brand Names

S2 Racepinephrine (Nephron, US OTC label); Adrenalin (L-epinephrine 1 mg/mL vials)

Pharmacologic Class

Sympathomimetic catecholamine; alpha- and beta-adrenergic agonist

Therapeutic Class

Croup and upper-airway edema adjunct (off-label); bronchodilator (racepinephrine labeling for asthma)

Controlled Substance

Not controlled

ISMP High-Alert

No for nebulized use. ISMP lists IV adrenergic agonists (EPINEPHrine is the example) as a high-alert class, and EPINEPHrine IM and subcutaneous as a specific entry (ISMP 2024 list)

Look-Alike / Sound-Alike

EPINEPHrine / ePHEDrine (ISMP); racemic 2.25% vs 1 mg/mL (1:1,000) vial, same drug family

Error-Prone Abbreviations to Avoid

Strength labels alone (2.25%, 1:1,000): state mg/mL and the dose in mg and mL