COFFEE.

On the down side are coffee's well-documented side effects: anxiety, insomnia, tremor and irregular heartbeat. It can also irritate the digestive system, bladder and prostate. If you experience any of these effects, you're better off avoiding coffee (and decaf, which contains substances that may contribute to the symptoms) no matter what potential health benefits it may have. The way coffee affects you is your surest guide to whether or not you should be drinking it at all and, if so, how much.


...from Dr. Weil website