I think, the answer depends on several factors like intensity of your headache, your weight and blood pressure. But the first thing I recommend to do is to read the detailed info about the pills. You can do this on Canadian Pharmacy Online site as it has the descriptions of all meds it offers. Hopefully, this info will be useful for you!
Extra strength excedrin is one kind of headache treatment product, which contains 65 mg caffeine in it. You can take one or two pills per day to relieve your headache. Hope this helps.