For clinicians treating adult anaphylaxis: epinephrine counters vasodilation, supports cardiac output and relieves bronchospasm. RCUK guidance.
The RCUK adult dose is 0.5 mg (500 micrograms): 0.5 mL of 1 mg/mL epinephrine, IM into the anterolateral mid-thigh. Repeat after 5 minutes for persistent airway, breathing or circulation problems. Call for help; give IV crystalloid for shock. Use a separate paediatric protocol for children. Adult treatment guidance.
Choose the needle and the scale
For manual IM injection, 25 mm is usual; some adults need 38 mm to reach muscle. Short fixed insulin needles may deposit drug subcutaneously. Needle guidance. Body habitus informs selection, but BMI alone cannot establish individual tissue depth. Ultrasound-based anatomical predictions do not prove clinical treatment failure. Anatomical study.
Use a syringe graduated in mL with an appropriate IM needle. Check drug, concentration, dose, volume and route. Insulin-unit markings refer to a specific insulin concentration, not epinephrine mass. A conversion chart does not establish device suitability. Follow device instructions and the local preparation standard. FDA syringe guidance.
Keep the route clear
Do not give this IM dose intravenously. Persistent respiratory or cardiovascular problems after two IM doses require urgent expert escalation for a titrated IV infusion with continuous monitoring. While the infusion is being arranged, repeat IM dosing every 5 minutes if these problems persist. IV epinephrine requires experienced specialists. Cardiac arrest requires CPR and the arrest algorithm. Escalation guidance.
Autoinjectors have product-specific doses and instructions; the manual dose above is not an instruction to modify an autoinjector. Example prescribing information. Use an appropriate available autoinjector promptly; do not delay treatment for ultrasound or a preferred needle. First-aid guidance.
