Hi Adriana - my only serious side effect from my Tykerb/Herceptin combo has been alternating bad diarrhea and loose stool. I tried using my bentonite clay, but it still doesn't seem strong enough, so I am relying on immodium about every 2-3 days. And I am trying my BRAT diet, too. I have been told by others that this side effect subsides over time, so I am counting on it. This is much much worse for me than anything I ever had with Tykerb/Xeloda. But I am only 2 weeks out from my first treatment on the T/H combo, so I will need to give it some time and see if it corrects...