Introduction to Administering an Intramuscular Injection
Intramuscular injection is one way of administering medications to a client. This route of administration can be used to deliver medications that may be too large or viscous to be given subcutaneously (SQ) into the subcutaneous tissue.
The nurse should ensure the correct equipment is available before beginning the procedure. Such equipment would include syringes, needles, and alcohol swabs.
Different needle sizes for intramuscular injections vary in size and length depending on the client’s body surface area and the medication to be injected. The most commonly used needle lengths for intramuscular injection are 1-inch or 5/8-inch, with the one-inch needle being the most frequently used.
As a nurse, you should always explain the procedure to the client and document afterward. Appropriate documentation of an Intramuscular injection includes:
- Client’s consent before administering an injection
- Time of the injection
- Drug amount
- Location of the injection
- Client’s response to the administration of the medication
Steps for an Effective Intramuscular (IM) Injection
To give an effective intramuscular injection, you’ll need to know how to prepare your hands and equipment, administer the injection, remove the needle safely, and dispose of it properly.
To deliver intramuscular injections, you’ll need:
Syringes – Syringes come in various sizes, but most syringes used for IM injections are between one cc and five cc.
Needles – The needle gauge used in IM injections must be the appropriate size to deliver the prescribed medication.
Alcohol pads – Alcohol pads help prevent infections from developing around the area where medication is being injected into muscle tissue (subcutaneous).
Bandages – After the injection is administered, bandages may be placed over wounds caused by needle insertion or blood collection devices (if applicable).
Needle Sizes Used in IM Injections
The needle size should be chosen based on the medication, and the type of muscle being injected. They must be thin enough to penetrate the skin easily and create minimal discomfort for the client, but thick enough to prevent accidental needle breakage or leakage of injected liquid into surrounding tissues.
The most common needle sizes used for intramuscular injections range from 22-27 gauge (thinner) to 31-34 gauge (thicker). In general, larger needles are used for deeper intramuscular injections and smaller ones for superficial ones.
The most common needle size used for an intramuscular injection is ⅝ to 1 ½ inch length. The most common gauge size is 22–25 gauge.
Here are some common needle sizes and their uses:
- 3/16″ to 1/4″ (4-5mm) 2-10 mL intramuscular injection of vaccines, insulin, vitamin B12, and other medications 10 mL intramuscular injections.
- 3/8″ (9 mm) 1-10 mL intramuscular injection of vaccines, insulin, vitamin B12, and other medications 10 mL intramuscular injections.
- 1/2″ (12 mm) 5-20 mL intramuscular injection of vaccines and other medications 20 mL intramuscular injections.
- 5/8″ (16 mm) 20-60 mL intramuscular injection of vaccines and other medications 60 mL intramuscular injections.
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How to Administer an IM Injection
Administering IM injections is essential to nursing, so it is crucial to learn how to administer medications or vaccines correctly.
Nursing documentation is required when giving an intramuscular injection. The nurse should document the following items after administering medications:
- The name of the medication along with any additional instructions from the health care provider (HCP).
- Any allergies or adverse reactions that may occur during an injection should also be noted.
- The use of a blood pressure cuff during administration so that this information can be shared with the HCP if necessary.
Here’s a step-by-step guide for giving IM injections:
- Prepare the appropriate supplies for the medication to be given: needle, syringe, alcohol wipes, and bandaid or sterile gauze.
- Check the prescription and check two client identifiers.
- Assess for any allergies.
- Perform hand hygiene.
- Draw up the appropriate medication, removing any air bubbles.
- Safely recap the needle to prepare to inject the client.
- Locate the anatomic site for injection.
- Clean and sanitize the area where the injection will be given to avoid any contamination.
- Remove the cap from the syringe and pull back on the syringe plunger until the air is expelled from the syringe, then discard the cap.
- With the non-dominant hand, inject the needle quickly into the muscle at a 90-degree angle, slowly injecting the medication.
- Once the medication is injected, remove the needle and cap safely. Cover the injection site with a bandaid or sterile gauze.
Complications of Intramuscular Injections
Intramuscular injections have a few potential complications that nurses should be aware of before administering to clients. Complications can occur when the needle is inserted incorrectly, when an improper substance is injected into the muscle tissue, or when a client has an allergy to the substance being injected.
It’s normal to have minimal pain and/or bleeding at the injection site. Any prolonged pain or bleeding is considered a complication.
Other possible complications include:
- Infection (including tetanus and staphylococcal infections)
- Abscesses at the injection site
- Nerve damage (if an artery has been punctured)
- Septicemia from bacteria entering through an open wound
- Anaphylaxis (if certain medications are used together)
- Blood clots in deep tissue resulting from trauma caused by inserting an improperly-sized needle through muscle tissue and into subcutaneous fat

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Intramuscular Injections Conclusion
Intramuscular (IM) injections are frequently used to deliver medicines too big or viscous to be administered subcutaneously.
As a nurse, you must become proficient in this skill to administer IM injections safely.
The needle size should be selected carefully depending on the drug and the muscle location. Complications can occur when there is an allergy to the medication injected or improper technique is utilized.