I had my first Herceptin three weekly injection last week. I had been having Herceptin intravenously with my chemo for past five months every three weeks. Chemo is now finished. I had a mastectomy yesterday afternoon. While waiting for my mastectomy yesterday morning my face and neck became very flushed. I also have had loose bowels.  Today has been the same with flushed face and neck, but without loose bowel. Could this be a delayed reaction to Herceptin injection? I never reacted like this when having intravenously.