Excedrin Migraine contains (per tablet):250 mg acetominophen250 mg aspirin 65 mg caffeineCoffee contains in the ballpark of 60-135 mg of caffeine per cup, and a 12 oz. Coke contains 35 mg.I personally think it's a bit bogus to put caffeine in a headache medicine, because a fair portion of the people suffering from headaches are in that situation in the first place due to overconsumption of caffeine followed by withdrawal symptoms.Given that IBS is characterized by spasms of the GI tract, and given that spasms are at their root caused by nervous system malfunction or overreaction, it seems a very poor idea for IBS sufferers to consume caffeine, because it is a nervous system stimulant.My IBS symptoms improved dramatically after eliminating modest levels of caffeine from my diet. A certain percentage of IBS folks might get the same benefit, who knows.