Side Effects of Targeted Therapy

Side Effects from taking Drugs for Targeted Therapies

Targeted therapy drugs used to treat breast cancer do not all fall into a single class of drugs. What they have in common is that they all have a specific target. This is different from systemic forms of cancer treatment, such as chemotherapy that affects organs throughout the entire body.

Each type of targeted therapy has its own associated side effects secondary to how they function. The following is a comprehensive list addressing the side effects for each drug specifically.


Anastrozole is classified as an aromatase inhibitor (AI).[1] The most common side effects from taking this drug for breast cancer are the following:

  • Nausea
  • Vomiting
  • Constipation
  • Diarrhea
  • Stomach or abdominal pain
  • Hot flashes
  • Sore throat
  • Back pain
  • Headache
  • Lymphedema
  • Bone pain/osteoporosis
  • High Blood Pressure
  • Sleeping difficulties/Insomnia
  • Dry skin
  • Sweating
  • Blood clots
  • Stroke


Lapatinib is a tyrosine kinase inhibitor, which blocks growth factors necessary for cancer cells to grow. The following are the most common side effects of this drug:[2]

  • Diarrhea, severe
  • Hand-foot syndrome, severe
  • Anemia
  • Nausea
  • Interstitial lung diseased
  • Cardiac arrhythmia
  • Low platelet count
  • Hepatotoxity- severe liver dysfunction


Tamoxifen is a hormonal therapy but since it has a specific target for selective estrogen receptors, it is also a targeted therapy. The most common side effects consist of:

  • Dry skin
  • Fatigue
  • Hot flashes
  • Night sweats

The more serious potential risks from taking this particular drug include the following:

  • Abnormal vaginal bleeding or discharge
  • Blood clots
  • Bone or joint pain
  • Depression
  • Endometrial cancer
  • Infertility and sexual dysfunction


Trastuzumab is a type of a monoclonal antibody. Side effects are typically less severe than hormonal therapy since the drug mimics an antibody that is naturally produced in your body. The following side effects are most commonly associated with this drug:

  • Nausea
  • Diarrhea
  • Vomiting
  • Fever
  • Chills
  • Generalized pain – particularly in the bones, joints and legs
  • Weakness or Fatigue
  • Headaches
  • Rashes
  • Cardiotoxicity
  • Pulmonary toxicity

Managing the Side Effects of Targeted Therapy Drugs

You cannot avoid all of the symptoms associated with targeted therapy drugs. Some of the side effects are a result of the function of the drug, and actually show that it is working. Be sure to tell your doctor if you think you are experiencing side effects of the medication. Below are some conventional and alternative methods of managing side effects associated specific targeted therapy drugs.

Targeted Therapy Drug Category Specific Side Effects Conventional Management of Side Effects Alternative Management of Side Effects
Trastuzumab (Herceptin) Monoclonal antibody NauseaDiarrhea

Weakness or Fatigue






Anti-nausea medicationCertain OTC drugs


Antibiotic gels

Institute a stop/start regimen, rely on pharmacotherapy for cardiac dysfunction[3]

Ginger or peppermint as tea or in dietary supplement formDigestive enzymes or probiotics, yogurtRest, improve your dietary intake
Lapatinib (Tykerb) Tyrosine kinase inhibitor Hand-foot syndromeAnemia

Diarrhea, mild






Mild rash




Reduce the dosage






antibiotic gel

Monitor regularly

Increase intake of iron-rich foods or take iron supplements, restAvoid all lactose-containing products, stay well-hydrated and eat small meals, try ginger or peppermint teas to ease the stomach



 Tamoxifen Selective estrogen receptor modifier (SERM) Dry skinFatigue

Blood clot formation


Monitoring and awareness

Moisturizing soaps and lotionsEat well-balanced meals, exercise, rest.
Anastrozole Aromatase Inhibitor (AI) NauseaVomitingConstipationDiarrheaStomach or abdominal pain

Back pain Headache


Dry skin


Dizziness or drowsiness


Loss of appetite


Anti-nausea medications are available

Acetaminophen or ibuprofen


Peppermint or ginger tea, lozengesDrink plenty of fluidsEat small meals


Moisturizers, moisturizing soap

Avoid driving or operating machinery


Try to eat small meals or take an appetite stimulant


Educate yourself on the side effects of each drug you are taking and be aware of those that may be more severe than others. Communicate with your doctor about your side effects and discuss potential options to relieve them. This may even mean trying a different drug. Open communication will help you and your doctor determine the best treatment strategy for your cancer.


1 Bonner, D (2008). The 10 Best Questions For Surviving Breast Cancer. New York: Fireside.

2 Moy, B; and Goss, PE (2007). Lapatinib-Associated Toxicity and Practical Management Recommendations. The Oncologist, 12 (7): 756-765.

3 Mackey, JR; Clemons, M; Côté, MA; Delgado, D; Dent, S; Paterson, A; Provencher, L; Sawyer, MB; and Verma, S (2008). Cardiac Management during Adjuvant Trastuzumab Therapy: Recommendations of the Canadian Trastuzumab Working Group. Current Oncology, 15(1): 24–35.

This article was originally published on July 27,2012 and last revision and update of it was 9/2/2015.