Medicines and prescriptions
What Does Intramuscular (IM) Mean on a Medicine?
Intramuscular · say it: IN-truh-MUS-kyuh-lerAlso written: IM, intramuscular injection, injection into a muscle
Short answer
Intramuscular (IM) means a medicine is injected into a muscle, usually the upper arm, thigh or buttock, from where it is absorbed into the blood.
What it means
Intramuscular means 'into the muscle'. An IM injection is given deep into a large muscle such as the deltoid (upper arm), the thigh or the buttock. Muscles have a good blood supply, so the medicine is absorbed steadily. Many vaccines, some antibiotics, vitamin B12 and long-acting medicines are given this way.
Labels state the route because the same medicine may be made for different routes, and giving it the wrong way can be harmful. Some long-acting IM injections release medicine over weeks. Labels may warn about pain or swelling at the injection site, and about care in people who bleed easily or take blood thinners.
It differs from subcutaneous (under the skin), intravenous (into a vein) and intradermal (into the skin) injections.
Where you may see it
- The 'Dosage and administration' section of injectable medicine labels
- Vaccination records ('IM, left deltoid')
- Hospital medication charts
📄 How it looks on a report
For intramuscular use only. Do not administer intravenously.
🙅 What it does not mean
- It does not mean the injection is stronger than a tablet.
- It is not the same as an injection under the skin.
- Soreness at the site for a day or two is common and does not usually mean something went wrong.
🎯 Check yourself
Which of these is the right meaning of “Intramuscular”?
🗒️ Questions to ask your doctor
🧾 Reports where you will see “Intramuscular”
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💊 Medicines whose labels mention “Intramuscular”
Plain-English explanations of each medicine, from its official FDA label.
- Ampicillin Sodium
a penicillin-type antibacterial medicine
- Ceftriaxone
A broad-spectrum cephalosporin antibiotic, as described on the official FDA label
- Diphenhydramine Hydrochloride
an antihistamine (an antihistaminic agent) given by injection into a vein or deep into a muscle
- Furosemide
A loop diuretic, a type of medicine that helps the body get rid of extra fluid through urine
🔗 Read more from trusted sources
- “Intramuscular” on MedlinePlus ↗
US National Library of Medicine
- NCI Dictionary definition ↗
US National Cancer Institute: “intramuscular”
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General information about a medical word, not advice about your own results. Ask the clinician who ordered the test what it means for you.