The docs can't give you a definite answer because they themselves have no idea whether or not it's harmful to combine with meds. There hasn't been any testing, sadly, because it's not considered an important enough substance to do real scientific testing on--and because the pharmaceutical industry doesn't want it even considered. Besides, with as many differences as there are among various strains, it'd be silly to provide a "yes, completely safe" or "no, completely unsafe" answer anyway since the strains have such different characteristics.

My own hesitation about smoking with those meds isn't because I think it's unsafe. It's because you're trying to make sure your prescription meds do their job correctly. And how can you accurately assess that when you're adding another psychoactive substance into the mix and you can't tell whether the effects you're experiencing are from the meds or the weed? You can't. Goodness knows it's lots safer than alcohol, generally, unless you have other underlying health problems that might be aggravated from smoking (and here I mean from smoking of anything, from cigarettes to weed).