Technique and Procedure of Intramuscular Injection

Technique and Procedure of Intramuscular Injection/Intramuscular Injection is the method of installing medications into the depth of the bulk of specifically selected muscles. The basis of this process is that 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. It is one of the most common medical procedures to be performed on an annual basis. However, there is still a lack of uniform guidelines and an algorithm in giving IM among health professionals across the world. 

Intramuscular injection, often abbreviated IM, is the injection of a substance directly into the muscle. In medicine, it is one of several methods for parenteral administration of medications. Muscles have larger and more numerous blood vessels than subcutaneous tissue; intramuscular injections usually have faster rates of absorption than subcutaneous or intradermal injections.[rx] The volume of injection is limited to 2-5 milliliters, depending on the injection site.

Anatomy and Physiology of Intramuscular Injection

Anatomical Landmarks

  • There are specific landmarks to be taken into consideration while giving IM injections so as to avoid any neurovascular complications. The specific landmarks for the most commonly used sites are discussed below

Dorsogluteal Region

  • 5 to 7.5 cm below the iliac crest.
  • Upper outer quadrant of the upper outer quadrant within the buttocks

Ventrogluteal Region

  • The heel of the opposing hand is placed in the greater trochanter, the index finger in the anterior superior iliac spine and the middle finger below the iliac crest. The drug is injected in the triangle formed by the index, middle finger, and the iliac crest


  • 2.5 to 5 cm below the acromion process

Vastus Lateralis

  • Possible sites for IM injection include – deltoid, dorsogluteal, rectus femoris, vastus lateralis and ventrogluteal muscles. Sites that are bruised, tender, red, swollen, inflamed or scarred are avoided.
  • The middle third of the line joining the greater trochanter of the femur and the lateral femoral condyle of the knee

Uses of Intramuscular Injection

Drugs may be given intramuscularly both for prophylactic as well as curative purposes, and the most common medications include:

  • Antibiotics- penicillin G benzathine penicillin, streptomycin
  • Biologicals- immunoglobins, vaccines, and toxoids
  • Hormonal agents- testosterone, medroxyprogesterone

Any drugs that are nonirritant and soluble may be given IM during an emergency scenario.

Examples of medications that are sometimes administered intramuscularly are:

  • Atropine
  • Haloperidol (Haldol)
  • Aripiprazole (Abilify)
  • Paliperidone (Invega)
  • Chlorpromazine (Thorazine)
  • Lorazepam (Ativan)
  • Fulvestrant (Faslodex)
  • Codeine
  • Morphine
  • Methotrexate
  • Metoclopramide
  • Magnesium sulfate
  • Olanzapine
  • Streptomycin
  • Diazepam
  • Prednisone
  • Penicillin
  • Interferon beta-1a
  • Sex hormones, such as testosterone, estradiol valerate, and medroxyprogesterone acetate (as Depo Provera)
  • Dimercaprol
  • Ketamine
  • Leuprorelin
  • Naloxone
  • Quinine, in its gluconate form
  • Vitamin B12, as cyanocobalamin, hydroxocobalamin or methylcobalamin
  • Risperidone

Vaccines are often administered as IM injections.

In addition, some vaccines are administered intramuscularly

  • Gardasil
  • Hepatitis A vaccine
  • Rabies vaccine
  • Influenza vaccines based on inactivated viruses are commonly administered intramuscularly (although there is active research being conducted as to the best route of administration).
  • Platelet-rich plasma injections can be administered intramuscularly.
  • Certain substances (e.g. ketamine) are injected intramuscularly for recreational purposes.

Indications of Intramuscular Injection

IM is commonly indicated for patients who are 

  • Noncompliant
  • Uncooperative
  • Reluctant
  • Unable to receive drugs through other commonly utilized routes

Contraindications of Intramuscular Injection

  • Active infection, cellulitis or dermatitis at the site of administration
  • Known allergy or hypersensitivity to the drug
  • Acute myocardial infarction- the release of muscle enzymes may provide a confounding bias in making the diagnosis
  • Thrombocytopenia
  • Coagulation defects
  • Hypovolemic shock- the absorption of the drug may be hampered owing to compromised vascularity to the muscle
  • Myopathies
  • Associated muscular atrophy- leads to delayed drug absorption as well as adds up the risk of neurovascular complications


  • 20-25 gauge syringe with a needle length of 16-38 mm
  • Filter needle
  • Alcohol-based antiseptic solution
  • The correct drug in an appropriate dose
  • Dry cotton swab
  • Self-adhesive bandage
  • Needle disposal unit
  • A trained nurse or a paramedics
  • The treating physician



Ensure the 5 ‘Rs’

  • Right patient
  • Right drug
  • Right dose
  • Right site
  • Right timing

Ask for any adverse reactions in previous such procedures.

Counseling regarding the procedure and preparing the patient– to calm them down and also to minimize the pain associated with the procedure

Site selection

  • Infants- vastus lateralis
  • Children- vastus lateralis and deltoid
  • Adults- ventrolateral and deltoid

Drug volume

  • 2 ml or less- deltoid injection
  • 2 to 5 ml       – Ventrogluteal injection

Needle length

  • Vastus lateralis -16 to 25 mm
  • Deltoid-16 to 32 mm (children), 25 to 38 mm(adults)
  • Ventrogluteal-38 mm

Technique of Intramuscular Injection

The sequential method of IM injection can be summarised as follows

  • Thorough cleaning of the hands
  • Application of sterile gloves
  • Thorough cleansing surrounding the site of injection with an alcohol-based antiseptic solution
  • Perpendicular insertion of a needle of appropriate sized length
  • Prepare the drug and then aspirate it from the filter needle
  • Insure intramuscular positioning of the needle via confirming restricted side to side movement of the needle as opposed to when the needle is in the subcutaneous plane
  • Aspirate to rule out any egress of blood especially in cases of dorsogluteal injection due to inadvertent vascular puncturing of the gluteal artery during the procedure
  • Slow injection of the drug at 10 sec/ml
  • Slow withdrawal the needle and then apply gentle pressure over the injected site with a dry cotton swab
  • Proper disposal of all the equipment used during the procedure
  • Assessment of  the injected region for probable early and late complications


Common complications  associated with the intramuscular injection can be summarized as :

  • Muscle fibrosis and contracture
  • Abscess at the injection site
  • Gangrene
  • Nerve injury -the sciatic nerve in gluteal injection, the femoral nerve in vastus lateralis injection
  • Vascular injury- the superior gluteal nerve in dorsogluteal injection, the femoral nerve in vastus lateralis injection, radial nerve in deltoid injection
  • Skin slough
  • Periostitis
  • Transmission of HIV, hepatitis virus
  • Persistent pain at the site of injection

Clinical Significance


  • Rapid and uniform absorption of the drug especially those of the aqueous solutions
  • Rapid onset of the action compared to that of the oral and the subcutaneous routes
  • IM injection bypasses the first-pass metabolism
  • It also avoids the gastric factors governing the drug absorption
  • Has efficacy and potency comparable to that of the intravenous drug delivery system.
  • Highly efficacious in emergency scenarios such as acute psychosis and status epilepticus
  • Depot injections allow slow, sustained and prolonged  action
  • A large volume of the drug can be administered compared to that of the subcutaneous route


  • Expert and a trained person is required for administrating the drug by IM route
  • The absorption of the drug is determined by the bulk of the muscle and its vascularity
  • The onset and duration of the action of the drug is not adjustable
  • In case of inadvertent scenarios such as anaphylaxis or neurovascular injuries, intravenous (IV) assess needs to be secured
  • IM injection at the appropriate landmarks may be difficult in a child as well as in  patients requiring physical restrain
  • Inadvertent injection in the subcutaneous plane of the fascia can lead to delayed action of the drug
  • Painful procedure
  • Suspensions, as well as oily drugs, cannot be administered
  • Can lead to anxiety to the patient especially in children
  • Self-administration of the drug can be difficult
  • The precipitation of the drug following faster absorption of the solvent may lead to delayed and prolonged action of the drug
  • Unintended prolonged sequelae following delayed drug release from the muscular compartment
  • Need for temporary restraint of the patients especially in cases with children


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