American Medical Association (AMA) Guides Newsletter [this excerpt summarizing the scientific research on the harmful effects of opioids and lack of effectiveness as a treatment for pain. There are 57 references. The full report is available from the AMA Bookstore.]

Scientific Findings Indicate That Narcotics Can Cause Pain To Worsen
Scientific findings have indicated that narcotics reliably cause an abnormally severe sensitivity to pain, termed hyperalgesia. For example, in what was claimed to be the only prospective study of the effect of narcotic medications on pain sensitivity among chronic low back pain patients, all of the participants demonstrated increased vulnerability to pain after just one month of utilizing prescription narcotics. The participants’ pain thresholds reportedly dropped by an average of 16%, and their pain tolerance reportedly dropped by an average of 24%.
In subsequent literature, the same researchers warned that the hyperalgesic effects of narcotic medications might be manifested in ways that include some of the common perplexing complaints from chronic pain patients, including unexplained pain reports (which is the essential nature of chronic benign pain), pain complaints that are discrepant from previous complaints, diffuse pain complaints, and allodynia. In a separately published “qualitative systematic” review, members of the same research team warned of the obvious risk that the hyperalgesic effects of narcotics will cause a worsening of the specific pain for which the narcotics were originally prescribed as a treatment.
This harmful effect of prescription narcotics does not appear to be permanent. For example, a more recent review has emphasized findings that indicate that pain presentations demonstrate improvement subsequent to the discontinuation of narcotics. The benefit that comes from eliminating narcotic prescriptions appears to be very reliable.

Narcotics Expand the Nature of the Patient’s Impairment Beyond Pain.
An additional concern is created by scientific findings that indicate that prescription narcotics cause other significant problems beyond the worsening of the pain. As is the case with the findings in regard to pain, these findings of other effects indicate that the patient’s general presentation of impairment could be temporarily.

Endocrine Disruption
One of the most prominently raised concerns in this regard involves endocrine disruption.
Hypogonadism (central suppression of hypothalamic secretion of gonadotropin-releasing hormone is one of the most well-documented examples of such endocrine disruption. A review of relevant scientific findings specified that symptoms of narcotic-induced hypogonadism include loss of libido, infertility, fatigue, depression, anxiety, loss of muscle strength and mass, osteoporosis, compression fractures, erectile dysfunction in men, and menstrual irregularities and lactation irregularities in women.
Fortunately, the effects appear to be reversible through the elimination of the consumption of narcotics.

Immune System Compromise
Another harmful effect of narcotics, specifically compromise of the immune system, has reportedly been recognized scientifically for 100 years and has reportedly been demonstrated for most forms of narcotic medication.

Cognitive Impairment
Research has also indicated that narcotics are a risk factor for cognitive impairment, even when the narcotic consumer does not perceive him- or herself to be sedated.

Substance Abuse
Readers might note that this discussion has not emphasized an issue that is usually mentioned early in discussions of prescription narcotics: substance abuse. This issue was not mentioned yet because several of the adverse effects reported above actually appear to be more pervasive. But substance abuse is indeed yet another area in which prescription narcotics appear to be playing a harmful role. For example, one review reported that substance abuse is common among patients with such prescriptions, with findings of the association between such prescriptions and substance abuse running as high as 56%.

Generalized Ill Health and Disability
The negative effects of prescription narcotics appear to extend even beyond pain, endocrine problems, sleep abnormalities, immune deficiency, cognitive impairment, and substance abuse. For example, in a large-scale study involving almost 2000 participants reporting pain, those who were utilizing narcotic medications were indeed more likely to have a current experience of severe pain and were also more likely to perceive their health as being poor in general, to be unemployed, to be utilizing the health care system more extensively, and to report a worse quality of life in all areas. Similarly, other research projects have repeatedly produced results indicating that the prescription of narcotics leads to dramatically higher rates of disability.

Narcotics Generally Lack Credibility as a Treatment For Chronic Benign Pain
An evaluator might wonder about a possibility that the adverse effects described above could be considered a burden of treatment compliance for any patient for whom a narcotic prescription is necessary and justified. But such wondering can be quickly put to rest by a review of the scientific literature, which creates significant generic obstacles to claiming that narcotics could be necessary or justifiable in any individual case of chronic benign pain. The professional literature provides a wealth of discussions of the lack of justification for narcotics as a treatment for chronic benign pain (examples provided below). This lack of justification takes several forms.

Lack Of Reliably Demonstrated Benefit for Chronic Benign Pain
One example of the lack of support for narcotics as a treatment for chronic pain is the published reports regarding the lack of treatment success. For example, one systematic review utilized meta-analysis of the most well-designed studies in order to analyze the effects of narcotics for chronic back pain and found that narcotics did not demonstrate an advantage in the reduction of pain compared to placebo or non-narcotic medication. That project also involved a review of the most well-designed studies that provided data on reduction of pain following a narcotic prescription compared to baseline and again found that there was not a significant reduction in pain associated with narcotic use.

A similar project discovered that, even among the most well-designed studies, some published claims of a statistically significant advantage for narcotics had been misrepresented. Those reviewers also noted that they could not find any well-designed studies that demonstrated a clinically significant benefit from narcotics compared to placebo or other forms of treatment. The reviewers concluded that the available science as a whole failed to provide support for narcotics as a treatment for chronic back pain.

The Actual Nature of the Presentation of Chronic Benign Pain is Being Ignored
Scientific findings have repeatedly and reliably indicated that the primary risk factors for chronic benign pain are of a psychological nature or a social nature. Given such indications that chronic benign pain is a psychological and social phenomenon, it is difficult to imagine any justification for narcotics as a treatment option.
Some of the most robustly established risk factors can be used as examples of this problem. For example, in the only relevant prospective research ever conducted, the only participants who developed persistent benign pain complaints were those who were eligible for compensation. Hopefully, it is obvious that there is no justification for narcotics as a “treatment” response to compensation eligibility. As another example, preexisting personality disorders appear to be the most prominent health care finding among chronic pain patients, including a greater than 70% rate of such preexisting disorders among workers’ compensation claimants with chronic disabling back pain complaints. Hopefully, it is also obvious that there is no justification for narcotics as a treatment for personality disorders.[1] 
  1. Barth R. Prescription Narcotics: An Obstacle to Maximum Medical Improvement, AMA Guides Newsletter March/April 2011