Hello, Butrans skin patches have one of the very strong pain killers that are required for continuous use in patients with such condition. It has a lot of side effects but the most dangerous is respiratory depression, in which your breathing starts decreasing causing you to have difficulty in breathing. If this happens then you have to immediately see a doctor who will prescribe a medication named as Naloxone. But this medication needs to be given under the supervision of a doctor. Regarding Fibromyalgia, Tramadol has commonly used medication, but many patients opt for much simpler pain killers as pain with fibromyalgia usually persists for the long term due to which taking strong pain killers such as Zamadol should be avoided. But if cant is avoided then I would suggest Zamadol rather than Butrans skin patches. Regarding the side effects of Zamadol stomach pain and diarrhea is possible in a small number of people. Usually, constipation is noted. But for such problem, you just have to stop the medication for a while and take some other pain killer like Panadol or paracetamol for time being. Then after your problems have settled then you can start again. Just remember that both of these medications may cause respiratory problems for which same medication will be used by the doctor to treat the side effects as I mentioned above. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr Talal Hussain, General & Family Physician