Are there any negative side effects of the pain killer Fioricet? the doctor prescribed Fioricet to me with regard to my migraines. My Rx says that I can take two tablets – 4 times a day. Are there any known long term side effects from using this drug? I take them pretty regularly. Nausea, vomiting,… Continue reading question and answer: Are there any negative side effects of the pain killer Fioricet?