Fiorinal is a drug that is used to relieve mild to moderate tension headaches. Fiorinal is a combination medication that is made up of caffeine, aspirin and butalbital. Aspirin works as a pain reliever, an anti-inflammatory agent and also reduces fever. Caffeine is a stimulant of the central nervous system (CNS) and it also improves the flow of blood by relaxing muscle contraction. Butalbital is a barbiturate. It works by relaxing the muscle contractions that are involved in any tension headache.