In the context of epinephrine dosing for anaphylaxis, what is the concentration used for IM administration?

• A. 1:2000
• B. 1:5000
• C. 1:1000
• D. 1:10000

Answer: (C)

When treating anaphylaxis, the intramuscular dose is given using a 1:1000 epinephrine solution because this concentration provides the standard 0.3–0.5 mg dose in a practical, small-volume injection. A 1:1000 solution has 1 mg of epinephrine per mL, so injecting about 0.3–0.5 mL delivers the typical adult dose (and auto-injectors are designed around this amount). Using concentrations like 1:2000, 1:5000, or 1:10000 would either require larger injection volumes to reach the same dose or are typically reserved for intravenous use, not routine IM treatment. So the IM concentration used for anaphylaxis is 1:1000.