How does morphine work to kill pain?

26 June 2011


Graphic of a woman with a headache



How is morphine is a painkiller? Since I smashed my ankle the pain is terrible. I have been put on oral morphine.
Thank you.......... Adrian


Morphine is one of the most famous painkillers. It's an opioid drug, which means it's a cousin of the ancient drug opium, which has been used socially and in medicine thousands of years.

These drugs bind to the opioid receptors, which are on the surfaces of nerve cells in the brain and spinal cord. This sets off a chain of chemical signals within the cell which ultimately cause the cell membrane to become less excitable.

This means that pain-sensing nerve cells become electrically "sluggish" and don't fire so many impulses. As well as dulling pain by silencing nerves in the spine that carry pain signals, morphine also has complex effects in the pain processing areas in the brain, including suppressing the action of the nerve pathways that control breathing, heart rate and blood pressure. This is why an overdose of morphine is so dangerous, because it can trigger a person to stop breathing, which is called a respiratory arrest.

Morphine receptors are also found on nerves all over the body. To cite on example, the nerves that supply the muscles in the gut are slowed down by morphine; this can cause severe constipation, which patients taking opioid drugs need to be made aware of.


Wounded as a corpsman in Vietnam in Nov of 67, I would years later be found to have suffered a TBI with loss of consciousness - a term not know to the military nor the VA and related medical communities. After suffering a minor R) occipital stroke in 2005 while at the work place - the VAMC - an MRI showed the damage done to the brain including an absence of White matter on my L) side and the damage that had brought on my inability to remember names or to enunciate words/medications unless seen or spoken frequently. So for over 25 years I was put on various narcotic pain meds that were largely ineffective although this writer practiced relaxation therapy, yoga, self hypnosis for pain relief and while employed received whole body acupuncture which did control the pain for 4-5 days.
So earlier this year, I discussed with my neurologist reducing my daily morphine dose from 180 mg including one or two more 30 mg tablets if needed. The med was never abused nor was any illegal drugs ever used - none. Several months ago I at age 72 decided again in consult with the neurologist of my completely stopping the use of the morphine which he and others agreed with; he also felt as I did that the morphine was having a diminishing effect on my pain control - neck and mid or thoracic back fracture histories from the wound. So
the morphine was stopped totally and it was soon obvious that the morphine was still providing some pain relief to the above areas in particular - but I have been off the med for nearly a month. Still have sig sinus pressure in my forehead, some runny noise, dry non productive cough, and sneezing. Am on an anti biotic med for the above. So, in realizing that my various receptors in my brain and CNS likely still have morphine stock piled within so to speak - a clean catch urine sample was done to validate any presence of morphine still in my body...thoughts or experiences. Thank you, David

So you are predisposed to expect morphine, within your pain receptors?

What do you mean?

Add a comment