Why are muscles used for intramuscular injections

Intramuscular injectionApplication typesInjections: An intramuscular route is used to inject a medicine into a skeletal muscle using a syringe and cannula. The drug enters the bloodstream via the blood vessels from the muscle.

synonymous: intramuscular administration, intramuscular application, intramuscular, IM, IM


An intramuscular injection is a medicine that is given into a skeletal muscle using a syringe and cannula. It gets from the muscle via the vessels into the bloodstream and is distributed throughout the body.

Intramuscular injection, click to enlarge. Illustration © PharmaWiki

Application sites

A common application site for small volumes of up to 2 ml is the deltoid muscle of the upper arm.

An intramuscular injection is also possible on the outside of the thigh and on the buttocks (gluteal muscle).

The application site depends on the drug. Not all drugs are suitable for all locations. This is also due to the different pharmacokinetics.


Drugs that are administered intramuscularly (selection):

General procedure

The general procedure is shown below. The procedure may vary depending on the medicine, the injection site and the patient. Please note the relevant specialist and patient information and specialist literature:

  • Indication and medical clarification including contraindications and interactions.
  • Allow refrigerated drugs to passively warm to room temperature.
  • Wearing gloves, disinfecting the skin.
  • Provision of the material, preparation of the syringe.
  • Visually inspect the contents of the syringe for foreign particles and any change in appearance.
  • Suspensions must be shaken before administration.
  • Some preparations require removal of air.
  • Disinfection of the skin area. Let the disinfectant take effect. Let the skin area dry.
  • Spread the skin with two fingers.
  • Hold the syringe like a dart.
  • Quickly insert the syringe vertically (90 °).
  • Let go of the skin.
  • Aspiration to prevent injection into a blood vessel. Inject elsewhere when drawing blood. In the case of vaccinations in the deltoid muscle, aspiration can be dispensed with.
  • Inject the contents of the syringe slowly into the muscle.
  • Spread the skin again.
  • Pull out the syringe quickly.
  • Stop any bleeding, gently compress the skin area with a sterile swab.
  • Disinfection of the skin area.
  • Put the plaster on.
  • Dispose of the material, the syringe in an appropriate disposal container.
  • Monitor the patient for adverse effects.
unwanted effects

Common undesirable effects of an intramuscular injection are local symptoms such as pain and a bruise, but these usually only last for a short time. Injections carried out incorrectly can lead to injuries and infections. The side effects depend on the drug administered.

Injections can cause allergic reactions and, very rarely, anaphylaxis.

Injections can cause unpleasant symptoms such as paleness, sweating, drowsiness, dizziness and fainting in some patients, see the article → Fear of injections.

An injection also poses a certain risk for specialists. They can accidentally stab themselves with the syringe, injure themselves and become infected with an illness.

see also

Fear of injections, types of application, intravenous injection

  • Pharmaceutical product information (CH)
  • Specialist literature

Conflicts of Interest: None / Independent. The author has no relationships with the manufacturers and is not involved in the sale of the products mentioned.

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This article was last changed on 7/12/2020.
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