Fioricet is a combination of Acetaminophen, Butalbital, and Caffeine. Acetaminophen is a pain reliever and fever reducer. Butalbital is in a class of drugs called barbiturates that slow down your central nervous system (brain and nerve impulses) causing relaxation. Caffeine is believed to constrict dilated blood vessels that may contribute to tension headaches. Together, acetaminophen, butalbital, and caffeine are used to relieve complex tension (muscle contraction) headaches although precisely how Fioricet works is unknown

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