Intramuscular injection or IM injection is an injection given directly into the central area of specific muscle. It is used for administration of certain drugs that cannot be delivered in other ways such as intravenous, orally or subcutaneously. The blood vessels of the muscle dispense injected drug through cardiovascular system.
The intramuscular method provides faster rate of absorption comparing to subcutaneous one, but much slower comparing to intravenous route. IM injection shouldn’t be given if size and condition of the muscle can’t sustain adequate absorption of the medication. Also, these injections shouldn’t be given at painful site.
Intramuscular Injection Sites
IM injections can be given on several sites on the human body. The three sites that are commonly used for intramuscular injection are deltoid muscle, vastus lateralis muscle and gluteus medius muscle. Which site will be used depends on muscle density of the each site and type of drug that will be injected.
Deltoid muscle is a three-headed muscle that caps the shoulder. IM injections can be given into deltoid muscle, if there is enough muscle mass.
Vastus lateralis muscle is the part of quadriceps of the upper leg. It is often used as IM injection site since it generally well formed and thick and because it isn’t near any major arteries or nerves.
Gluteus medius is one of the three gluteal muscles situated on the outer surface of the pelvis. This muscle is often used site for intravenous injections and it is known as ventrogluteal site.
Before injecting, a caregiver must prepare the medication from the vial or ampule. Patient must be placed in comfortable position that will provide access to the injection site. The injection area must be wiped with an alcohol swab and dried. Cover of the needle must be taken off, syringe inverted and excess air expelled.
Caregiver must depress and pull the skin with his free hand. After that he or she will pierce the skin and enter the muscle. The needle must be injected at a 90 degree. Health care provider should aspirate (pull back on the plunger) to make sure that blood vessels aren’t punctured. In case the blood appears in the syringe, the needle and syringe must be disposed and new injection prepared. If blood isn’t aspirated, medication can be injected. After administering the injection, the needle must be pulled quickly.
The site may be briefly massaged, depending on the given medication. After injecting, a patient should be monitored for signs of redness, swelling, bleeding or inflammation at injection site. Patients should be monitored for signs of reaction to the medication as well.
Complications of intramuscular injections are usually caused by injected medication rather than the procedure. Minor pain is normal for a short period after administration of the drug.