If hydrocodone is in the same class, it's part of what I take for migraines, and I do not having breathing issues with it (except for once, when I mis-timed a dose, which I will NEVER do again ... yikes ... but the warning is because it slows your breathing when you do that, and yep, it did as advertised). With a patch, it's pretty hard to mis-time it the way you can a pill, so if that's the breathing concern, that shouldn't be too bad ... but again, that's the sort of thing you ask a doctor and/or a pharmacist, to be sure. (My pharmacists are angels, always checking for allergies and interactions that even my doctors might have missed.) And I don't *think* I had any of that stuff before my cancer treatments, but my memory is so hazy, I can't be sure ... I wasn't taking it during treatments, for sure, because of the whole tube thing. Just went straight to the patch.

Can you call a pharmacist this weekend with some of your questions? They're busy, but way less busy than an ER. Depends on how well you know yours and trust them. And it can be nice to get some questions answered sooner, so you have the meds before your treatment. Or maybe fill the prescription just in case, but don't start it till you talk to your doctor? I just hate to think of you suffering more treatments while waiting for answers and THEN going to get it filled, when you could have it on hand and ready to go... but again, I'm a sympathetic fellow patient and NOT a doctor.