"My new doctor told me that my use of cannabis for pain from fbromyalgia would cancel out the effects of Cymbalta for the condition and recommended that I stop using any cannabis products. I have been using them together for years and had found a pretty decent balance for control of my symptoms. I didn’t go with complaints, just a script refill check-up. Intead of asking me if I used weed he said that he wanted to test some levels of possible problems with a blood test. I was not aware of the drug test specific to cannabis until I got my bill in the mail. I have looked for the "many" studies that he says are out there on the subject and have not found much at all. "
I have not encountered any studies stating that CBD would interfere in pain relief provided by Cymbalta. Perhaps your doctor was talking about the fact that CBD and Cymbalta compete for the same enzymes involved in their breakdown—as described in the answer I provided (above yours).
However, that would not reduce the efficacy of Cymbalta. In fact, if very high doses of CBD are taken with Cymbalta, that may even lead to a higher serum concentration of Cymbalta to provide pain relief.
What’s worse, is the fact that your physician disregarded your assessment that the combo of CBD and Cymbalta provided superior analgesia when compared to Cymbalta alone…and, without any noticed adverse effects, I imagine.
Also, I’m not sure what blood test he used to measure for CBD, as I am unaware of any such test widely available. She could test for THC. However, that won’t say anything about CBD levels. And what’s the point anyways? "Your blood test is positive for CBD. So, now I know you actually do use CBD." Perhaps he was checking liver function? If so, tell him studies show CBD as beneficial to liver health.
I hope this helps!