This post was originally published on the Medical Care Blog in February 2017.

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High-quality evidence supports the use of medical marijuana for chronic pain, neuropathic pain, and other conditions. Yet, patients who live in some states can’t legally use it — and are threatened with loss of access to their prescribed pain medications if they do.

I know this because a close family member of mine has chronic pain. She has fibromyalgia, migraines, neuropathic pain, rheumatoid arthritis, and numerous other health issues, resulting in 21 surgeries. She has been taking prescription opioids for 15 years.

She wishes she could use marijuana for her pain, because she knows from experience that it works — and with minimal side effects, unlike opioids. Marijuana reduces migraine frequency, reduces pain, and improves her functionality and quality of life. But she can’t use medical marijuana legally, because she lives in North Carolina. North Carolina does not allow medical usage for any of her conditions – only epilepsy.

Even worse, her pain clinic tests her urine twice a year, and marijuana is one of the drugs they test for. Her pain clinic will cut her off if she tests positive. In this threat, they are consistent with North Carolina’s Medical Board guidelines to doctors who prescribe opiates [PDF]. If a patient smells like marijuana or has a positive urine screen, the guidelines suggest this “should raise the physician’s awareness about the possibility that a patient is seeking opioid medications for reasons other than legitimate pain relief.”

My relative is, in her own words, a “disabled senior citizen,” hardly a candidate to be selling her medications. She is trying to cope with the burden of multiple painful conditions, with little respite. In her own words:

One of my issues is the tolerance that has developed for my pain medication and the limitation put on the strength. I have been on 30mg of extended release MSIR [morphine] for 3 years … and I would have to say on a scale of 1-10 [my pain is still a] 6 every day. This in turn reduces my motivation to exercise and move because I know it will increase my pain…

Her daily pain medication regimen is associated with side effects ranging from chronic constipation to sleep apnea and respiratory depression, not to mention opioid-induced hyperalgesia. And still her pain is insufficiently managed.

In March, 2016, the CDC published guidelines for opioid prescribers: stop testing for marijuana:

Clinicians should not test for substances for which results would not affect patient management or for which implications for patient management are unclear. For example, experts noted that there might be uncertainty about the clinical implications of a positive urine drug test for tetrahyrdocannabinol (THC).

This is just one battle in the ongoing civil war in the medical community over pain. And there remain many questions about how cannabis should be used in practice. But in my view, it is time for prescribers to change their drug-testing policies. There is little evidence that testing for marijuana prevents opioid diversion. However, testing for THC — and dumping patients that test positive — presents plenty of risks for patients: barriers to access to care, lack of adequate pain management, and disruption in care continuity, for starters.

Time will tell whether the ongoing global marijuana legalization experiment will ultimately be a boon, a bane, or both. There are encouraging signs; for example, states that have medical marijuana dispensaries have seen a relative decrease in opioid addictions and opioid overdose deaths [PDF]. Regardless, there is little continued justification for drug-testing for marijuana in pain clinics. Instead, doctors should consider the evidence for marijuana as a potential therapeutic partner in treating pain.

Lisa M. Lines, PhD, MPH is a health services researcher at RTI International, an independent, non-profit research institute. She is also an Instructor in Quantitative Health Sciences at the University of Massachusetts Medical School. Her research focuses on quality of care, care experiences, and health outcomes among people with chronic illnesses; emergency department utilization; and person-centered care and patient-centered medical homes, among other topics. She is co-editor of TheMedicalCareBlog.com and serves on the Medical Care Editorial Board.