Intramuscular Injections, How and Where to Give

An intramuscular (IM) injection is a shot of medicine given into a muscle. Medicines that must be given into a muscle include:

  • Medicines that need to take effect quickly.

  • Medicines that cannot be taken in other ways, such as swallowed by mouth, injected into a blood vessel, or absorbed through the skin.

CHOOSING A SITE FOR INJECTION

There are 4 main sites that can be used for IM injections. If many injections need to be given, injections should be given in different sites (rotated) each time. An injection should be separated from the previous site by 1 inch (2.5 cm). The ideal site depends on your age, size, and amount of medicine in the injection.

  • Thigh (vastus lateralis muscle). This site is located by dividing the thigh into thirds between the knee and hip. The site is located in the middle, outer sides of the thighs. This site is usually used for infants and toddlers. The maximum amount of medicine that should be injected in this muscle is 4 mL.

  • Top of upper arm (deltoid muscle). One method to locate this site is to place the palm of a hand centered on the person's shoulder. Your fingers should be pointing toward the floor. The thumb and the other fingers are separated to make an upside down V shape. The IM injection should go in the middle of the V shape. This site is usually used for children age 3 and older and adults. This site can be used in children under 3 years of age if the muscle mass is adequate. The maximum amount of medicine that should be injected in this muscle is 1 mL.

  • Hip (ventrogluteal or gluteus medius muscle).One method to locate this site is to place the heel of your hand on the person's hip, on the upper side of his or her leg. Your hand should be placed so your fingers are facing his or her head. You should feel the upper edge of the bony pelvis with your ring finger and little finger. Point your thumb to his or her groin. Spread your index finger and middle finger into a V shape and give the injection between those fingers. This site can be used for children age 7 months and older and adults. There is no maximum amount of medicine for this injection site.

  • Buttocks (dorsogluteal muscle). One method to locate this site is to divide one buttock into 4 quarters. The quarters are formed by dividing the buttock in half from top to bottom and also in half from side to side. The injection should be given in the upper, outer quarter. This site can be used for children and adults. The maximum amount of medicine that should be injected in this muscle is 4 mL. This site does have a high risk of hitting a nerve, blood vessel, or bone.

CHOOSING A NEEDLE FOR INJECTION

A needle used for an IM injection needs to be long enough to go through the skin and tissue and end deep in the muscle. Needles have two measurements: a needle diameter (called a gauge) and a needle length (denoted in inches or mm). The bigger the gauge, the smaller the needle diameter. The smaller the gauge, the bigger the needle diameter. The needle gauge for an IM injection should be 22 to 25 gauge. Needle length depends upon age and size of the individual and the injection muscle.

Age: Newborn (Birth to 1 month)

  • Weight: Any weight

  • Injection Site: Thigh

  • Needle Length: ⅝ inch (16mm)

Age: Infant (1 month to 1 year)

  • Weight: Any weight

  • Injection Site: Thigh

  • Needle Length: 1 inch (25mm)

Age: Child (1 to 2 years)

  • Weight: Any weight

  • Injection Site: Thigh

  • Needle Length: 1 to 1 ¼ inch (25 to 31 mm)

Age: Child (1 to 18 years)

  • Weight: Any weight

  • Injection Site: Deltoid

  • Needle Length: ⅝ to 1 inch (16 to 25 mm)

Age: Child (2 to 18 years)

  • Weight: Any weight

  • Injection Site: Any site, except deltoid

  • Needle Length: 1 to 1 ¼ inch (25 to 31 mm)

Age: Adult

  • Weight: Less than 130 lb (less than 60 kg)

  • Injection Site: Any site

  • Needle Length: ⅝ inch (16 mm)

Age: Adult

  • Weight: 130 to 152 lb (60 to 70 kg)

  • Injection Site: Any site

  • Needle Length: 1 inch (25 mm)

Age: Adult

  • Weight: Women: 152 to 200 lb (70 to 90 kg), Men: 152 to 260 lb (70 to 118 kg)

  • Injection Site: Any site

  • Needle Length: 1 to 1 ½ inch (25 to 38.1 mm)

Age: Adult

  • Weight: Women: greater than 200 lb (greater than 90 kg), Men: greater than 260 lb (greater than 118 kg)

  • Injection Site: Any site

  • Needle Length: 1 ½ inch (38.1 mm)

ADMINISTERING AN IM INJECTION USING MEDICINE FROM A VIAL

  1. Gather supplies: medicine vial, alcohol wipe, syringe with the appropriate gauge and inch needle.

  2. Wash your hands.

  3. Check the date on the medicine vial to make sure the medicine is not expired.

  4. Clean the top of vial with an alcohol wipe. Be sure that the cover has been removed on new vials.

  5. Let the top of the vial dry.

  6. Carefully remove the needle cover. Do not touch the needle.

  7. Pull air into the syringe equal to the amount of the medicine dose you need.

  8. Stick the syringe needle into the top of the medicine vial.

  9. Inject the air into the vial. Leave the vial upright.

  10. Leave the needle in the vial and turn the vial and syringe upside down.

  11. Pull down slowly on the plunger, drawing the medicine into the syringe. You may need to push the plunger up and down 2 to 3 times to slowly rid the syringe of air bubbles.

  12. Pull the medicine into the syringe to the dose you need.

  13. Remove the needle and syringe from the vial.

  14. Use alcohol to clean the area of the body to be injected.

  15. Hold the muscle of the injection site firmly between your thumb and fingers of one hand.

  16. With the other hand, hold the needle and syringe like a pencil. Using a quick dart-like motion, insert the needle at a 90-degree angle through the skin and into the muscle.

  17. Release your hold on the skin and muscle.

  18. Pull back slightly on the plunger to see if blood is present. If there is blood, remove the needle and syringe and start over with a new needle and syringe. If there is no blood, inject the medicine.

  19. Push the plunger slowly down to inject the medicine into the muscle. Some medicines are gels and require force to inject into the muscle.

  20. Take the needle out.

  21. Apply pressure at the injection site and gently rub the site.

  22. Apply a bandage if needed.

  23. Discard the used needle and syringe properly.

  24. Store the medicine vial as directed.

SEEK MEDICAL CARE IF:

  • The patient feels like he or she is having side effects or an allergic reaction from the medicine.

  • The medicine was injected incorrectly.

  • You or someone else is unable to give the injection.

  • The patient has a rash, swelling, or continued bleeding or pain at an injection site.