What’s the Deal: IM vs. IV Injections

When one says the term “Nurses”, they often envision people in an all-white ensemble, with a cap, a ready smile and a syringe, or injection as some may say, in one hand. Some nurses may say that they feel that they are registered nurses when they take hold of a syringe more than administering per orem medications. It makes them feel “more important”. Well, while some nurses feel confident with a syringe at hand, some are still confused when it comes to telling apart IM from IV Injections.

Which is which?

Injection provides a more powerful rush than any other method of administration and the advantageous effects can be attained with smaller doses. With this, injection appears to be the most cost-effective method of delivery. As both IV and IM medications are ways of delivering a medication, they differ and are the same in some ways.

Route: Intravenous injection (IV) is forcing of a liquid directly into a vein or into a person’s bloodstream while Intramuscular injection (IM) is one made into the substance of a muscle.

Dosage and bioavailability: The dosages for intravenous and intramuscular injections are usually similar, and generally lower than doses of comparable oral medications. However, the IV route takes the drug directly into the bloodstream which results in 100% bioavailability instantaneously while in the case of an IM route, drug is injected into muscle tissues, which holds the drug for a while and slowly releases into the bloodstream through the network bed of capillaries running across or surrounding the muscle tissue. In this sense, the bioavailability may be somewhat less than 100% of drug due to dispersion from muscle through tissue fluid and into the blood.

Efficacy: While a number of IM injections are given in the deltoid muscle, such as for vaccines, or in the buttocks, IV injections are given in an already established IV line or into a vein in the arm. IV Therapies make use of relatively high dose vitamins, minerals, homeopathics and botanicals given to a person through a needle directly into their blood circulation while other vitamins and minerals are believed to be most effective only when administered at an IM route.

While both IM and IV routes offer quicker efficacy than oral medicines, they also face some risks such as site infection, damaged blood vessels, arterial hits and many more.

Injecting a medicine may give someone an intense rush. Some may even feel addicted and pleasured. But remember, as nurses, it is best to understand and know how to administer a medicine first like knowing the 10 R’s when administering medications, because failing to do so may not only result to wrong route and simple complications, little do we know, it could cost a patient’s life just by a simple act of negligence.




Liane Clores, RN MAN

Currently an Intensive Care Unit nurse, pursuing a degree in Master of Arts in Nursing Major in Nursing Service Administration. Has been a contributor of Student Nurses Quarterly, Vox Populi, The Hillside Echo and the Voice of Nightingale publications. Other experience include: Medical-Surgical, Pediatric, Obstetric, Emergency and Recovery Room Nursing.

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