Intramuscular injection

Intramuscular (or IM) injection is the injection of a substance directly into a muscle. In medicine, it is one of several alternative methods for the administration of medications (see Route of administration). It is used for particular forms of medication that are administered in small amounts. Depending on the chemical properties of the drug, the medication may either be absorbed fairly quickly or more gradually. Intramuscular injections are often given in the deltoid, vastus lateralis, ventrogluteal and dorsogluteal muscles.

Complications and contraindications

When the gluteal muscles are used, injections should be made on the upper, outer quadrant of the buttock to avoid damaging the sciatic nerve. Injection fibrosis is a complication that may occur if the injections are delivered with great frequency or with improper technique.

Thrombocytopenia (low platelet counts) and coagulopathy (bleeding tendency) are contraindications for intramuscular injections, as they may lead to hematomas.

Uses

Examples of medications that are sometimes administered intramuscularly are:

codeine
morphine
methotrexate
metoclopramide
olanzapine
Streptomycin
diazepam
prednisone
penicillin
Interferon beta-1a
sex hormones, such as testosterone, estradiol valerate, and Depo Provera
dimercaprol
ketamine
lupron
naloxone
quinine in its gluconate form

In addition, some vaccines are administered intramuscularly:

Gardasil
hepatitis A vaccine

Influenza vaccines based on inactivated viruses are commonly administered intramuscularly, although there is active research as to the best route of administration.

Also certain substances (i.e. ketamine) are injected intramuscularly for recreational purposes.