Targeted Therapy Side Effects

Targeted therapy drugs are designed to stop or slow the growth or spread of cancer. This happens on a cellular level. Cancer cells need specific molecules (often proteins) to survive, multiply and spread. These molecules are usually made by the genes that cause cancer and the cells themselves. Targeted therapies are designed to interfere with, or target, these molecules or the cancer-causing genes that create them.

What are the side effects of targeted therapy?

There are many different types of targeted therapy drugs, and their side effects depend on the type of drug a patient is taking and what it targets. Some targeted therapy drugs have side effects because the proteins they are meant to attack are also found in normal cells. The side effects of targeted therapy may include:

• Skin problems, such as rash, itching, or dry skin
• Constipation
• Nausea and vomiting
• Cough
• Low red blood cell count, leading to fatigue
• Low white blood cell count, which may increase the risk of infection
• Poor blood clotting and wound healing
• High blood pressure
• Diarrhea
• Mouth sores
• Sores around the fingernails or toenails
• A loss of hair color
• Swelling in the face, feet, legs and hands
• Shortness of breath or trouble breathing
• Damage to organs such as the thyroid gland, liver, or kidneys
• Allergic reactions (while getting an intravenous (IV) drug)

Your doctor may prescribe medicines to prevent targeted therapy side effects from happening or treat them once they occur. While most targeted therapy side effects go away after treatment ends, it’s important to inform your care team about any symptoms you experience or changes in your overall health.

When to call your cancer care team about side effects

While many side effects are temporary, others may indicate serious problems. Contact your care team if you have any of the following symptoms during targeted therapy treatment:

• A fever higher than what your care team told you to expect
• An allergic reaction
• Intense chills
• Pain at your injection site or catheter site
• Long-lasting diarrhea or vomiting
• Blood in your stool or urine

Learn more about targeted therapy.