Quote from davidpt40:

Coffee CERTAINLY causes acne. It causes an adrenal response in the body, which causes increased oil secretion and skin temperature.

One study showed skin temperature on the face rises .5 degrees after drinking a cup of coffee. May not sound like much, but it is.

Your right David...I just looked it up, and caffeine, theophylline (what's found in tea) and *****romine (which is in chocolate) all inhibit cAMP Phosphodiesterase, prolonging the effects of the hormones responsible for generating cAMP (cyclic adenosine mono phosphate) cAMP is responsible in 2nd messenger systems which are regulated by several different hormones, and activate different processes.