@irontoenail - Even caffeine is supposed to be bad with beta blockers so I guess that would be even more of an issue. Most people know not to mix alcohol with medication after all, no matter how harmless the medication is.
This is generally to protect the liver, since most medicines are difficult to process, and alcohol is too, so both together can damage the liver.
But I wouldn't even think of caffeine as being an issue if I was taking medication.
It makes sense when you think about it, since caffeine is supposed to affect the heart, and I know it can cause palpitations in people if they have too much.
But I'll bet most people don't know that.