To inject epinephrine with a syringe, you draw the correct dose from a vial of 1:1,000 (1 mg/mL) concentration, then inject it into the outer thigh muscle at a 90-degree angle. The standard adult dose is 0.3 to 0.5 mg, which equals 0.3 to 0.5 mL from a 1 mg/mL vial. The entire process takes under a minute once you know the steps.
Equipment You Need
For an intramuscular injection in the thigh, adults need a 22- to 25-gauge needle that is 1 to 1.5 inches long. A 25-gauge needle is thinner and causes less pain; a 22-gauge is slightly wider and allows the medication to flow faster. For children aged 1 to 10, a 1-inch needle is typically sufficient. The syringe itself should be a standard 1 mL syringe with clear volume markings so you can measure the dose precisely.
You also need an alcohol swab, a cotton ball or gauze pad, and the epinephrine vial. Make sure the vial is labeled 1:1,000 (1 mg/mL). A different concentration, 1:10,000, exists for intravenous use in hospital settings and contains only one-tenth the amount of epinephrine per milliliter. Using the wrong concentration is a well-documented source of serious dosing errors.
Checking the Dose
For adults and children over 25 kg (about 55 pounds), the standard intramuscular dose is 0.3 mg, which is 0.3 mL from a 1 mg/mL vial. Some guidelines allow up to 0.5 mg for larger adults. Children between 5 and 25 kg receive 0.15 mg (0.15 mL). For infants under 5 kg, the dose is calculated by weight at 0.01 mg per kilogram.
Before drawing, inspect the vial. Epinephrine should be clear and colorless. If the liquid looks brown, pink, or cloudy, do not use it.
Drawing Epinephrine From the Vial
Wash your hands thoroughly with soap and water and let them dry. Then follow these steps:
- Fill the syringe with air. With the cap still on the needle, pull back the plunger to the line that matches your dose. If you need 0.3 mL of medication, pull the plunger to the 0.3 mL mark. This loads the syringe with an equal volume of air.
- Insert the needle into the vial. Remove the needle cap without touching or bending the needle. Push the needle through the rubber stopper on top of the vial.
- Push the air in. Press the plunger down to inject the air into the vial. This equalizes pressure inside the vial and keeps the medication flowing smoothly into the syringe.
- Invert the vial. Turn the vial upside down so it’s above the syringe. Make sure the tip of the needle stays submerged in the liquid the entire time.
- Pull back the plunger. Draw the medication down to the line that matches your dose.
- Check for air bubbles. If you see bubbles in the syringe, tap the barrel gently with your finger to float them to the top, then push the plunger slightly to expel the air back into the vial. Pull back again to confirm you still have the correct volume.
- Remove the needle. Pull it straight out of the vial. The syringe is now ready.
Finding the Injection Site
The target is the vastus lateralis, the large muscle on the outer side of the thigh. To locate it, imagine a line from the bony bump at the top of your outer hip (the greater trochanter) down to the bony knob on the outside of your knee (the lateral femoral condyle). The injection site sits roughly halfway between those two points, on the outer front portion of the thigh.
This muscle is preferred because it’s large, easy to access (you can inject through clothing in an emergency), and has fewer major blood vessels and nerves than other sites. During anaphylaxis, when seconds matter, the outer thigh is the fastest and safest target whether you’re injecting yourself or someone else.
Performing the Injection
Clean the skin at the injection site with an alcohol swab and let it air dry for a few seconds. If this is an emergency and no swab is available, skip this step rather than delay the injection.
Hold the syringe like a dart in your dominant hand. With your other hand, use your thumb and index finger to spread or lightly grip the muscle tissue around the site. In a quick, firm motion, push the needle straight into the muscle at a 90-degree angle, perpendicular to the skin. Insert the needle to its full depth so the medication reaches deep into the muscle tissue rather than staying in the fat layer beneath the skin.
Push the plunger down steadily to inject all the medication. There’s no need to pull back on the plunger first (a technique called aspiration) for this type of injection. Once the syringe is empty, pull the needle straight out and press a cotton ball or gauze pad against the site for a few seconds.
What to Do After Injecting
Epinephrine works fast. You should notice some improvement in breathing, swelling, or other anaphylaxis symptoms within minutes. If symptoms do not improve or they return, a second dose of the same amount can be given 5 to 10 minutes after the first. Most people need only one dose, but repeat injections at that interval are safe if the situation demands it.
After injecting, lay the person down with their legs elevated (unless they’re having trouble breathing, in which case sitting up is better). Even if symptoms improve, anaphylaxis can return in a second wave hours later. Emergency medical care is always necessary after an epinephrine injection, regardless of how well the person responds.
Storing Epinephrine Properly
Epinephrine breaks down when exposed to heat, cold, or light. Vials and pre-filled syringes should be stored at room temperature, between 20°C and 25°C (68°F to 77°F), with brief excursions up to 30°C (86°F) considered acceptable. Keep the vial in its original packaging or in a dark container to protect it from light. Do not refrigerate or freeze epinephrine, and avoid leaving it in a hot car or direct sunlight. Check the expiration date regularly, as degraded epinephrine loses potency and may not work when you need it most.