Most people I know regularly consume coffee. I never liked coffee because it would make my IBS worse, but I did take low dose caffeine pills in the past. Recently, I suffered serious effects of caffeine withdrawal. For about four months straight, I consumed about 100-250 mg of caffeine per day. That is about 1-2.5 cups of coffee, and less than one strong Starbucks coffee. When I suddenly stopped taking the caffeine pills I noticed a few adverse effects.