The article discussed "CYP2D6 inhibitors like Wellbutrin and DXM" and I can offer one data point. An officemate came in with a bad cough one day. I had over-the-counter cough medicine with DXM handy and he took some. He had never taken DXM before; it is apparently not common in his country of origin.

He felt "shaky" and generally terrible after taking the DXM, and almost went to the hospital. I had never encountered anyone having that reaction before.

That particular colleague was also, it turns out, on a pretty hefty dose of Wellbutrin. I never knew there was a possible connection between the two until now.