This may have been a rumor started by the tea industry, and one that is eminently de-bunkable: drinking coffee will NOT give you an ulcer. The thinking, until recently, was that excess stomach acid caused ulcers and that coffee contributed to excess stomach acid. While some people may experience heartburn after drinking coffee, there's NO conclusive evidence that coffee makes the stomach produce excess acid. An ulcer is an open sore in the digestive tract. Most ulcers are found in the stomach and top of the small intestine. When stomach acid comes in contact with an ulcer, it can become quite painful. Recent studies have shown that ulcers are actually caused by a certain bacteria, Heliobacter pylori, and that these ulcers can actually be easily cured with antibiotics. An important distinction to make, however, is that while coffee or spicy foods don't CAUSE ulcers, they may serve to aggravate existing ones.