Herceptin Side Effects and Warnings

After its approval by the FDA, then Health and Human Services Secretary Donna E. Shalala summarized Herceptin's promise, "For certain women with advanced disease, this new product can mean new hope."

But Herceptin is not without side effects. Up to 28% of all women taking the drug with chemotherapy agents experienced heart problems, including cardiomyopathy. This is a potentially life-threatening heart muscle weakness that can lead to congestive heart failure. This side effect is particularly common in women receiving chemotherapy with drugs known as anthracyclines (including a common breast cancer therapy called doxorubicin) and cyclophosphamide.

For this reason, the FDA recommends that every woman considering Herceptin have a thorough cardiac assessment before taking the drug and during Herceptin treatment. Recent data suggests, however, that the risk of permanent heart damage is fairly low and likely does not exceed 4% of women receiving the drug. In most cases, the benefits of Herceptin—when indicated—greatly outweigh the risks.

When first administered, Herceptin can also produce mild chills, fever, pain, weakness, nausea, vomiting, and headache in up to half of all women. But these side effects are much less likely to recur with each new dose, a significant improvement over most cancer-fighting treatments. Also, the side effects commonly seen with standard chemotherapy—including hair loss, mouth sores, and bone marrow suppression—are rare with Herceptin. However, the treatment can exacerbate some other side effects of chemotherapy, including anemia, diarrhea, abdominal pain, and infection.