Each person's reaction to a cancer drug is different. Some people have very few side effects, while others may experience more. We have outlined the most common side effects. We have not included those that are rare, however, and which are therefore extremely unlikely to affect you. If you notice any effects that you think may be due to the drug, but which are not listed below, please discuss them with your doctor or nurse.
Effects on the heart Herceptin may lead to some people having heart problems. For that reason it is recommended that Herceptin is not given to people with a history of heart disease or high blood pressure.
In order to check your normal heart function, you will have tests (usually an echocardiogram) before starting treatment with Herceptin.
Flu-like symptoms This includes a high temperature (fever) and chills, shortly after the drug is given. These symptoms can be controlled or reduced with medicines, which your doctor can prescribe for you.
Tumour pain Some people may experience mild pain in parts of the body to which the breast cancer has spread. Painkillers can be given to relieve this.
Diarrhoea This can usually be controlled with medicine, but let your doctor know if it is severe or if it continues. It is important to drink plenty of fluids if you have diarrhoea.
Headaches Let your doctor know if you have headaches while having treatment with Herceptin.
Allergic reactions This is a rare side effect of Herceptin. Signs of this include skin rashes and itching, wheezing, difficulty breathing, and breathlessness. You will be closely monitored during your treatment, but let your nurse or doctor know if you have any of these symptoms. To reduce the chance of developing an allergic reaction, antihistamines can be given before the infusion. The infusion can also be slowed down or stopped until the reaction is over.
If you have any questions about these or any other side effects, talk to your doctor or nurse.
If Herceptin is given in combination with chemotherapy you will also experience the side effects of the chemotherapy drug.