What sort of pain? Is this from inflammation? I don't use pain killers per se of any kind, and prefer topical analgesics if anything or heat / cold application to the affected area. If this is more cerebral (Headache) or nerve based, rather than muscular, I'd differ to someone else. I usually have a headache due to dehydration or lack of carbs. I'm beginning to just poke at possibilities for your post. What specifics are you experiencing?
My wife is on a number of medications, and that's got me additionally leery of such devices.