Best Body Parts for Intramuscular Injections
The best areas for an intramuscular injection are areas that contain more muscle, less veins and nerves, and no bone.
There are 6 preferred areas, 3 on each side of the body, where an intramuscular injection can safely be given. It is important to choose the area that works best for you, and to rotate these injection sites to prevent sore muscles and scar tissue than can cause permanent damage. If you inject yourself in the same place even as often as once or twice a week, scar tissue will replace healthy muscle tissue. This scar tissue not only causes abnormal pain, but it can also affects how the medication will be absorbed. If have been instructed by your nurse or doctor on the best injection sites for your body structure and medication type, follow their directions.
Muscle structure also changes with age and body types. For example, the deltoid area may work well for a person with developed muscles in the upper body. The deltoid should not be used if in patients with limited muscle development because, there is not enough muscle tissue to properly distribute medication.
The injection site you chose must be easy to reach. You must be comfortable reaching across your body and holding the syringe in your hand. If you try and pick a spot that is difficult to reach, you may not get the medication all the way into the muscle, making it less effective.
What are the 3 Primary Injection Sites?
Thigh Muscle– Vastus Lateralis (VAS-tuss lat-er-AL-iss)
For most patients, the thigh muscles are the easiest to use for self injection. The thigh area is one of the largest on the body, making it easily accessible for both right and left handed patients.
To locate the correct injection site on the thigh, put your thumb in the middle of the top of the thigh, and your fingers along the outer side and press down gently. The muscle you feel between your fingers is the vastus lateralis. When using this muscle for injection, in your mind, divide the thigh into three equal parts. The middle third is where the injection should be given.
Upper Arm Muscle– Deltoid (DEL-toyd)
This site is difficult to use for self injection because many people have difficulty getting the syringe in the correct position. However, the deltoid muscle works well if the injection is being given by a third party that can reach the muscle.
To locate the best place for injection in the upper arm, start with a completely exposed upper arm. You will give the shot in the center of an upside down triangle. Feel for the bone that goes across the top of the upper arm. This bone is called the acromion process. The bottom of the bone forms the base of the triangle. The point of the triangle is directly below the middle of the base at the level of the armpit. The correct area to give a shot is in the center of the triangle, 1 to 2 inches (2.5 to 5 cm) below the bottom of the acromion process.
Buttock Muscle – Dorsogluteal (door-so-GLUE-tee-ull)
This site is difficult to use for self injection due to the inability for most people to turn around and inject themselves. The upper buttock area is the area where most people have received injections.
To locate the best place for an injection site in the buttock muscle, expose one entire buttock. With an alcohol wipe draw a horizontal line from the top of the crack between the buttocks to the side of the body. Starting in the middle of the horizontal line, draw a vertical line straight down approximately 3 inches. This will be the area with the most muscle on the outer buttock and your injection site.