Painkilling opioids like morphine could actually prolong pain rather than reduce it, according to new research on mice.
Scientists found that just a few days of treatment with an opioid led to chronic pain that went on for months.
In the long-term, the opioid increased the pain signals sent from immune cells in the spinal cord.
Some of the most common opioids are:
- meperidine (Demerol),
- hydrocodone (Hysingla ER, Zohydro ER),
- fentanyl (Actiq, Duragesic, Fentora),
- hydrocodone/acetaminophen (Lorcet, Lortab, Norco, Vicodin),
- hydromorphone (Dilaudid, Exalgo),
- and methadone (Dolophine, Methadose).
Professor Peter Grace, who led the study, said:
“We are showing for the first time that even a brief exposure to opioids can have long-term negative effects on pain.
We found the treatment was contributing to the problem.”
The study on mice treated an injury with opioids.
The scientists found that the long-term consequences of taking the drugs were serious.
The injury plus the opioid delivered a kind of ‘one-two punch’ to cells in the spinal cord called microglia.
Professor Linda Watkins, one of the study’s authors, said:
“The implications for people taking opioids like morphine, oxycodone and methadone are great, since we show the short-term decision to take such opioids can have devastating consequences of making pain worse and longer lasting.
This is a very ugly side to opioids that had not been recognized before.”
Around 20,000 people in the US died of prescriptions opioid overdoses in 2015.
Increased pain is not the only risk from opioids, they are also addictive.
People given opioid pain medication are 25% more likely to use the drugs chronically, a recent study found.
Study author Dr Susan Calcaterra said:
“These drugs are highly effective for pain control, but also cause feelings of euphoria.
For these reasons, patients may ask their physicians for additional opioid medication even after their acute issue is resolved.”
Dr Calcaterra continued:
“…patients [given opioid painkillers] were more likely to become chronic opioid users and had an increased number of opioid refills one year post-discharge, compared to patients without opioid receipt.
They were five times more likely to be chronic users after one year.”
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