Injections are classified in multiple ways, including the type of tissue being injected into, the location in the body the injection is designed to produce effects, and the duration of the effects.They are several common types:

Intramuscular Injection

Intramuscular injection,abbreviated as IM, delivers medications quickly into a person’s muscle tissue and can be employed for vaccines, antibiotics, or hormones.It administered at a 90° angle.The best location for these shots is in the upper outer quadrant of the buttock area, with care taken to ensure proper injection technique so that there will not be any issues with nerve damage. 

IM injections are commonly used for vaccines, certain antibiotics, and medications requiring a sustained release into the body.

Subcutaneous Injection

Subcutaneous injection, abbreviated as SC or sub-Q,  commonly provide medication under the skin’s surface, in the fatty layer. It i administered between 45° and 90° angles.Absorption of the medicine from this tissue is slower than in an intramuscular injection. Since the needle does not need to penetrate to the level of the muscle, a thin and short needle can be used. 

They’re frequently employed for delivering insulin and other blood thinners like heparin into parts of the body tissue, either the lower abdomen or thighs.