What does IM mean on a prescription?
IM means intramuscular — an injection into a muscle, usually the upper arm, thigh, or buttock.
- Means:
- intramuscular
- Type:
- How to take it
- Also written:
- im, i.m., IM
What it means in practice
Muscle has a good blood supply, so an IM injection is absorbed faster than one under the skin but more slowly than straight into a vein. Most adult vaccines are given IM, as are adrenaline auto-injectors.
Example on a prescription
Ceftriaxone 1 g IM once
Give a single 1 g dose of ceftriaxone by injection into a muscle.
Commonly confused with
- IVIV is into a vein, which acts fastest.
- SQSQ or subcut is into the fat under the skin, which absorbs more slowly.
Frequently asked questions
What does IM mean on a prescription?
Give it as an injection into a muscle.
What is the difference between IM and IV?
IM goes into muscle and is absorbed over minutes. IV goes directly into a vein and acts almost immediately.
Related abbreviations
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This page explains prescription notation for general information. It is not medical advice and does not replace your prescriber or pharmacist. If a label is unclear or differs from what you were told, check with your pharmacy before taking the medicine.