Meds + caffeine = ? Dangerous? Side effects? Cam?

Been trying to ask my pdoc this but been having a hard time getting through, maybe you know?
I'm on Welbutrin, Effexor, Lithium and Abilify, and they've said to limit caffeine. Why is this? Is excess caffeine dangerous, or does it simply produce aggravated side effects? Something, I think the Effexor, is making me really sleepy, which makes getting schoolwork accomplished very difficult. So caffeine would be very helpful in counteracting that, and I don't care about irritating side effects, just about getting the work done. But if it's actually dangerous to have much caffeine with these medicines then I wouldn't try it.
Any help?

Taonuviel - I wouldn't say that it is dangerous to consume caffeine with these medications, but the caffeine has been known to interfere with the action of lithium, Wellbutrin™ (bupropion) and Abilify™ (apiprazole).

The range of plasma concentrations between effective and toxic levels in lithium is narrow. A slight change in plasma concentration can increase the risk of toxic side effects (eg. diarrhea, increased tremor, fatigue, etc.).

Caffeine inhibits ADH (antidiuretic hormone) which results in water not being reabsorbed as efficiently by the kidneys and the excess water is peed off. In other words, caffeine is a diuretic; too much can significantly reduce the amount of water in the body thus increasing the concentration of lithium in the bloodstream, perhaps to toxic levels.

As for the Wellbutrin, it has some stimulant action, and so does caffeine, and there is an additive effect. This can bring about nervousness and anxiety.

The stimulant effects of the caffeine counteract the sedative effects of the Abilify, decreasing Abilify's effectiveness.

It is not an absolute no-no to stop caffeine, but it would simplify any further changes to your drug profile. - Cam