Intramuscular injection (IM) is installing medications into the depth of specifically selected muscles. The bulky muscles have good vascularity and therefore the injected drug quickly reaches the systemic circulation and thereafter into the specific region of action bypassing the first-pass metabolism. Here are the sites on the body that are considered to be safe:

What are IM Injections used for?

Intramuscular injections are a common practice in modern medicine. They’re used to deliver drugs and vaccines. Several drugs and almost all injectable vaccines are delivered this way.

Intramuscular injections are used when other types of delivery methods are not recommended. These include:

• oral (swallowed into the stomach)
• intravenous (injected into the vein)
• subcutaneous (injected into the fatty tissue just under the layer of skin)

Intramuscular injections may be used instead of intravenous injections because some drugs are irritating to veins or because a suitable vein cannot be located.

They may be used instead of oral delivery because some drugs are destroyed by the digestive system when you swallow them.

Intramuscular injections are absorbed faster than subcutaneous injections. This is because muscle tissue has a greater blood supply than the tissue just under your skin. Muscle tissue can also hold a larger volume of medication than subcutaneous tissue.