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Intramuscular injection
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<p>Intramuscular injection, often abbreviated IM, is the <a href="/facts/Medical_injection/fvkH58gk">injection</a> of a substance into a <a href="/facts/Muscle/dmxrL8pH">muscle</a>. In <a href="/facts/Medicine/2fnp90Je">medicine</a>, it is one of several methods for <a href="/facts/Parenteral/LsyoHTzH">parenteral administration</a> of medications. Intramuscular injection may be preferred because muscles have larger and more numerous <a href="/facts/Blood_vessel/FG3GjPNW">blood vessels</a> than subcutaneous tissue, leading to faster absorption than <a href="/facts/Subcutaneous_injection/L4srK61u">subcutaneous</a> or <a href="/facts/Intradermal_injection/dsBv9Ke2">intradermal injections</a>. Medication administered via intramuscular injection is not subject to the <a href="/facts/First-pass_metabolism/jfDsbq7S">first-pass metabolism</a> effect which affects oral medications. </p><p>Common sites for intramuscular injections include the <a href="/facts/Deltoid_muscle/se9ub2Ld">deltoid muscle</a> of the upper arm and the <a href="/facts/Gluteal_muscle/GXExQvGC">gluteal muscle</a> of the buttock. In infants, the <a href="/facts/Vastus_lateralis_muscle/pKpD2dP3">vastus lateralis muscle</a> of the thigh is commonly used. The injection site must be cleaned before administering the injection, and the injection is then administered in a fast, darting motion to decrease the discomfort to the individual. The volume to be injected in the muscle is usually limited to 2–5 <a href="/facts/Milliliter/QKwbQz8I">milliliters</a>, depending on injection site. A site with signs of infection or muscle atrophy should not be chosen. Intramuscular injections should not be used in people with <a href="/facts/Myopathy/eklaDeY6">myopathies</a> or those with trouble clotting. </p><p>Intramuscular injections commonly result in pain, redness, and swelling or <a href="/facts/Inflammation/Ura86MIy">inflammation</a> around the injection site. These side effects are generally mild and last no more than a few days at most. Rarely, <a href="/facts/Nerve/q7GsAfYV">nerves</a> or blood vessels around the injection site can be damaged, resulting in severe pain or <a href="/facts/Paralysis/Sh1Rqr8R">paralysis</a>. If proper technique is not followed, intramuscular injections can result in localized infections such as <a href="/facts/Abscess/BW3TH8kb">abscesses</a> and <a href="/facts/Gangrene/5AqvjjSj">gangrene</a>. While historically aspiration, or pulling back on the syringe before injection, was recommended to prevent inadvertent administration into a vein, it is no longer recommended for most injection sites by some countries. </p>