Morphine is in a class of medications called opiates. This class of medication ranges from weak opiates such as tramadol and codeine to much stronger opiates such as hydrocodone, oxycodone, oxymorphone, and fentanyl. A recent study from Ghent Belgium found no significant difference between placebo and 10mg of oral morphine a day in patients with rheumatoid arthritis. The only differences detected was in pain pressure thresholds in patients with Chronic Fatigue Syndrome, Fibromyalgia, and/or Rheumatoid Arthritis. The study was published in the July 19, 2017 issue of Pain Practice.
"Naloxone did not significantly affect nociceptive modulation in the healthy participants. These results suggest that temporal summation and conditioned pain modulation are not primarily mediated by opioid mechanisms," said Linda Hermans, P.T., from Ghent University in Belgium
These findings are similar to the results of a Cochrane review entitled Opioid therapy for treating rheumatoid arthritis pain. In that study the authors found only an 18% improvement over placebo but a much larger number of side effects associated with morphine.
Although 57 people out of 100 in the morphine treatment group reported a 'good' or 'very good' improvement in symptoms, 40 people in the placebo group reported similar improvement. The study was short term and only lasted 4 weeks. Since the effects of opiate pain relief tend to reduce over time, the small difference in these two groups is likely to reduce over time.
51 people of 100 people in the Cochrane review had at least one side effect when taking morphine compared to 20 in the placebo group. Common side effects with morphine include nausea, drowsiness, and constipation. More serious side effects are common including falls, confusion, increased risk of car wrecks, worsening of sleep apnea, respiratory depression, unintentional overdose, and death.
Essentially, the placebo group achieved 70% of the benefit of the opiate group with 1/2 the side effects.
The authors concluded:
There is limited evidence that weak oral opioids may be effective analgesics for some patients with RA, but adverse effects are common and may offset the benefits of this class of medications. There is insufficient evidence to draw conclusions regarding the use of weak opioids for longer than six weeks, or the role of strong opioids.