Morphine is a painkiller from the opiate family. It acts directly on the central nervous system (CNS), reducing the sensation of pain. It can be taken for both acute and chronic pain and is often used for severe pain after heart attacks, kidney stones, and during labor. Morphine can be given by mouth, by injection into a muscle, by injection under the skin, intravenously, by injection into the space around the spinal cord, or rectally. Because opioids can cause severe dependence, morphine is only available with a narcotic prescription.



Morphine acts in the central nervous system on μ-, κ-, and δ-opioid receptors. Primarily by binding to μ-receptors, pain transmission in the brain is inhibited, resulting in the analgesic effect. Activation of opioid receptors disrupts presynaptic calcium influx, leading to hyperpolarization in the cell and thus decreased excitability. Postsynaptically, morphine activates potassium channels, increasing the potassium efflux. This also results in hyperpolarization and decreased excitability of the nerve cell.


Morphine is absorbed in the alkaline environment of the upper intestine and rectal mucosa. The bioavailability of morphine is 80-100%. Morphine is 35% protein bound in the blood. Morphine is 90% metabolized by glucuronidation through UGT2B7 and sulfation. Morphine is 90% metabolized by glucuronidation and sulfation. 70-80% of the administered dose is excreted within 48 hours. Morphine is excreted predominantly in the urine and to a lesser extent in the stool.


Side effects

Common side effects

  • Constipation
  • nausea or vomiting
  • drowsiness
  • dizziness and spinning sensation (vertigo)
  • confusion
  • headache
  • itching or rash

Serious side effects

  • difficulty breathing or short shallow breathing
  • muscle stiffness
  • severe dizziness and tiredness (hypeotonia)
  • seizures or convulsions

If you have a seizure or convulsion, seek emergency medical attention immediately.

Toxicological Data

LD50 (rat, oral): 335 mg-kg-1

Chemical & physical properties

ATC Code N02AA01, N07BC09
Formula C17H19NO3
Molar Mass (g·mol−1) 285,34
Physical State solid
Melting Point (°C) 253–254
PKS Value 8,21
CAS Number 57-27-2
PUB Number 5288826
Drugbank ID DB00295


  • Drugbank
  • PubChem
  • NHS
  • Aktories, Förstermann, Hofmann, Starke: Allgemeine und spezielle Pharmakologie und Toxikologie, Elsvier, 2017

Editorial principles

All information used for the content comes from verified sources (recognised institutions, experts, studies by renowned universities). We attach great importance to the qualification of the authors and the scientific background of the information. Thus, we ensure that our research is based on scientific findings.
Markus Falkenstätter, BSc

Markus Falkenstätter, BSc

Markus Falkenstätter is a writer on pharmaceutical topics in Medikamio's medical editorial team. He is in the last semester of his pharmacy studies at the University of Vienna and loves scientific work in the field of natural sciences.

Mag. pharm. Stefanie Lehenauer

Mag. pharm. Stefanie Lehenauer

Stefanie Lehenauer has been a freelance writer for Medikamio since 2020 and studied pharmacy at the University of Vienna. She works as a pharmacist in Vienna and her passion is herbal medicines and their effects.

The content of this page is an automated and high-quality translation from DeepL. You can find the original content in German here.


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