When I was diagnosed with rheumatoid arthritis in 1981 a couple of weeks after turning 30, all of the effective Rx's were tough on the stomach and 40 years later dietary discretion is necessary. The only way coffee is on the menu is heavily dosed with buffers like non-dairy creamer. After my second hip replacement in 2002 I developed fibromyalgia (auto-immune conditions run in the family) and caffeine in high concentrations became necessary to any kind of semi-normal functions. Low or no sugar Rockstar energy drink became my best friend and my Rheumatologist gave it a thumbs up. These days my morning starts with the lemonade flavor hydration formula, 140 mg of caffeine and 25 calories per 16 oz. can with a minuscule bit of sugar, lots of B vitamins and other things that support liver function like milk thistle root. It actually tastes like lemonade and mixed 50/50 with iced tea is quite tasty on hot summer afternoons. When the barometer drops like a rock as it did around noon today, causing my fibro to flare, chugging one of their Pure Zero flavors with 240 mg of caffeine and no carbs whatever helps me get moving again. In the days before fibromyalgia, that much caffeine would have kept me climbing the walls for hours, now it just allows me to get off my behind and focus on a project. I tried a Red Bull once and poured the balance down the sink.