IV vs IM Injections: Understanding the Difference & Speed of Action

Intravenous and intramuscular injections are ways of delivering medicine. Intravenous injections are given via a syringe directly in a person's vein and into the bloodstream. Intramuscular injections are given directly into a muscle.

Dosage

• The dosage for intravenous and intramuscular injections usually are similar, and generally lower than doses of comparable oral medications.

Delay in effect

• Intravenous and intramuscular injections act quickly because the drug gets into the bloodstream faster than an oral medication.

Where to inject

• Many intramuscular injections are given in the deltoid muscle, such as for vaccines, or in the buttocks. Intravenous injections are administered in an already established IV line or into a vein in the arm.

Injection pain

• Both kinds of injections can result in pain and allergic reactions. These problems often are treated with Benadryl or an antihistamine.

Depot Medications

• Depot medications are drugs given by intramuscular injection that are released slowly into the bloodstream. An example is Provera for birth control.