The first time you get a Herceptin infusion (usually delivered by IV during a weekly hospital visit), you may feel like you're coming down with the flu. About 40% of women get chills, fever, nausea, vomiting, headache, and dizziness. But these side effects usually get better after the first treatment and become quite tolerable during the standard year-long therapy.
Julie R. Gralow, MD, director of breast medical oncology at the University of Washington and Fred Hutchinson Cancer Research Center in Seattle, cautions that heart trouble can be a side effect of taking Herceptin, especially if you take it along with certain chemotherapy drugs such as Adriamycin. Your doctor may want to test your heart before putting you on Herceptin and possibly also during the period that you remain on treatment.