Morphine
- Class: Opioid agonist
- Used for: severe pain
- Say it: MOR-feen
- Forms: tablet, capsule, oral liquid, injection
Remember the name – MORPH → Morpheus
MORPHINE is named for MORPHEUS, the god of dreams. It carries severe pain away into his arms.
The etymology is real. So is the warning inside it: the same mu receptors that take the pain also take the breathing, which is why respiratory depression is the thing to watch.
MORPHINE is named for MORPHEUS, the god of dreams. It carries severe pain away into his arms.
The etymology is real. So is the warning inside it: the same mu receptors that take the pain also take the breathing, which is why respiratory depression is the thing to watch.
Mnemonic: Morphine means the Mu receptor
Every classic opioid effect comes from that one receptor: pain relief, constipation, pinpoint pupils and slowed breathing. Learn the receptor and the side-effect list writes itself.
Every classic opioid effect comes from that one receptor: pain relief, constipation, pinpoint pupils and slowed breathing. Learn the receptor and the side-effect list writes itself.
Side effects
Common: constipation, nausea, drowsiness
Serious: respiratory depression, dependence
Typical dose
5–10 mg every 4 hours orally; 2.5–5 mg intravenously
Oral to intravenous is roughly 3:1 — 30 mg by mouth is about 10 mg into a vein. Prescribe a laxative at the same time.
Check yourself
Which morphine side effect does NOT settle with continued use?
- Constipation
- Nausea
- Drowsiness
- Itching
Show answer
A. Constipation
Tolerance develops to nausea, sedation and itching within days, but never to the effect on gut motility. That is why a laxative is prescribed alongside from the first day, not when the problem appears.
See it, don't memorize it
The app has the mechanism comic and a patient case for Morphine – plus the name link, the class mnemonic, pronunciation you can hear, and a self-check, for the top 100 drugs. One purchase, no subscription, no account.