Are there any negative side effects of the pain killer Fioricet(Butalbital APAP Caffeine)? My doctor prescribed Fioricet(Butalbital APAP Caffeine) to me for my migraines. My Rx says that I can take 2 pills - 4 times a day. Are there any known long term side effects from using this drug? I take them pretty regularly. Best answer: Answer by Comrade Demitri Dingleberry Plague and genital rats. Give your answer to this question below!