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Side effects of

Like any medication, targeted therapies can have side effects. Although some effects are more common with certain medications, each person experiences targeted therapies differently. Not everyone experiences all side effects. It's important to talk with your doctor about possible treatment side effects and how they can be managed. 

Most side effects of targeted therapies are temporary. The effects of targeted therapies may vary depending on your general health, the type of agent and dose you are on, other medications you are taking, the site of your cancer and other factors. It's important that you report any symptoms or changes in your health status to your doctor. 

Some of the common side effects of  may include:

Some of these effects may improve with medication or other medical interventions. For a list of specific side effects for different types of targeted therapies, see the table below

Allergic reactions

Any therapy can cause an allergic reaction in someone who is sensitive to the medication. Allergic reactions may range from mild to severe. Rarely these reactions can be fatal. Your oncologist may prescribe medication to decrease your risk for severe allergic reactions caused by

Anemia, bleeding and low white blood cell counts

Some targeted therapies damage bone marrow, where blood cells are made. This can result in too few red blood cells (anemia), too few platelets (thrombocytopenia) and a low white blood cell count (neutropenia).These bone marrow effects can lead to symptoms like fatigue, rapid heart rate, bleeding and increased risk for infection. Most of the time, these changes are mild. Your oncologist may test your blood, to make sure that your blood counts do not drop too low, which could delay treatment. 

Birth defects

Many targeted therapies can cause birth defects. Women are cautioned not to become pregnant while on . It's important to speak with your doctor about your plans for pregnancy before starting treatment. 


You should report fatigue to your doctors so they can check you and treat you for underlying causes, including depression, sleep disturbances and medication side effects. You may also be able to improve your energy level with these suggestions: 

  • making sure that your diet is balanced and provides you with adequate nutrition. Ask your doctor for a referral to a nutritionist if you need help figuring out your nutritional needs.
  • making sure that you get adequate sleep. 
  • trying to stay physically active, which can help improve your energy level. 

Heart damage

Certain targeted therapiesespecially anti-Her2 therapiescan cause heart damage. Your oncologist may run tests to make sure that your heart function is normal before, during and after treatment. Some drugs may help protect the heart from damage caused by targeted. Heart damage caused by treatment can also be minimized by lowering the dose, changing how it is given or switching to different drug.  

Joint or muscle pain

Certain targeted therapies may cause joint or muscle pain. Exercise, yoga and acupuncture may also help relieve joint pain. Ask your doctor about whether you can take nonsteroidal anti-inflammatories or other medication to improve joint pain caused by these therapies.

Mouth and tongue sores

Some targeted therapies can cause painful sores of the mouth and lips (called stomatitis), which can make eating painful. Certain medications and mouthwashes can help to repair mouth cells, coat the sores or block the pain caused by the sores. Rinsing your mouth with salt or baking soda can also improve mouth sores. 

Nausea, vomiting and appetite changes

Several medications help to reduce nausea during treatment. This can improve appetite, reduce weight loss and support a balanced diet—referral to a nutritionist can help assure that you maintain a balanced diet during treatment. Certain foods may be more or less likely to trigger nausea, vomiting or upset stomach. 

Nerve damage, tingling and pain

Some  drugs can damage nerves, leading to symptoms of pain, numbness, tingling or weakness in the arms, legs, hands and feet. These symptoms are known as peripheral neuropathy. Medications may help improve this condition. Physical therapy, acupuncture and certain types of exercise may also help to reduce symptoms and improve strength and balance. 


Rashes are a common side effect of some targeted therapies. They may range from mild to severe, depending on the agent.  

Risk for additional cancers

Increased risk for certain cancers may occur after treatment. The risk is usually small. Cancers that may be increased include skin cancers (reported with BRAF and MEK inhibitor combinations) and acute myeloid leukemia (reported with PARP inhibitors). 

Table of side effects

The table below lists some of the most common and the most serious side effects associated with different types of treatment. This is not a complete list. Report all symptoms or changes in your health to your doctor. You may also report any suspected side effects directly to the online or by calling: 1-800-FDA-1088.

Type of agent Names of agents Common side effects Serious side effects
Anti-Her2 kinase inhibitor Tukysa (tucatinib) Diarrhea; nausea; fatigue; fertility problems; abnormal liver values in the blood; vomiting; mouth sores; decreased appetite; stomach pain; headache; anemia; rash Severe diarrhea, severe liver problems
Anti-Her2 therapy

Herceptin (trastuzumab)
&  biosimilars (e.g.,Trazimera)

Kadcyla (trastuzumab emtansine)
Perjeta (pertuzumab)
Phesgo (pertuzumab, trastuzumab, and hyaluronidase-zzxf)

Allergic reactions, constipation, diarrhea, fatigue or weakness, fever and chills, hairloss, joint and muscle pain, low blood counts, mouth sores, nausea, neuropathy, rash, vomiting, Heart disease, severe allergic reaction
BRAF and MEK inhibitor Braftovi (encorafenib)
Mektovi (binimetinib)

When used in combination with Mektovi (binimetinib): fatigue, nausea, vomiting, abdominal pain, and joint pain. 

When used in combination with Erbitux (cetuximab): fatigue, nausea, diarrhea, rash, abdominal pain, decreased appetite and joint pain 

Risk for development of new skin cancers, bleeding problems, eye problems, heart rhythm problems
BRAF inhibitor and MEK inhibitor

Tafinlar (dabrafenib)
Mekinist (trametinib)

Tafinlar (dabrafenib) when used in combination with Mekinist (trametinib):  fatigue, fever, chills, nausea, vomiting, diarrhea, rash, decreased appetite, headache, cough, joint pain, pain in the hands and feet, high blood pressure

May cause new skin cancers, bleeding problems, intestinal tears, eye problems, heart rhythm problems

CDK 4/6 inhibitor Ibrance  (palbociclib)
Kisqali (ribociclib)
Verzenio (abemaciclib)
Anemia, infections, fatigue, nausea, vomiting, loss of appetite, sore mouth, thinning hair, abnormal liver values in the blood, rash Low white blood counts, severe lung inflammation, liver damage, heart rhythm abnormalities (Kisqali),
EGFR inhibitor Erbitux (cetuximab) Headache, nausea, diarrhea, rash and itching, fingernail and toenail changes, low blood counts, mouth sores, weakness   Severe or fatal allergic reactions, heart attacks, lung disease
EGFR inhibitor Vectibix (panitumumab)

Most common side effects when used alone include: skin rash, infections at the side of the fingernails or toenails, fatigue, nausea, and diarrhea

Most common side effects when combined with chemotherapy include: abnormal levels of magnesium, calcium and potassium; weakness; nausea; loss of appetite; diarrhea; skin rash; mouth sores

Severe skin reactions, serious allergic reaction
MTOR inhibitor Afinitor (everolimus)       Mouth sores, nausea, vomiting, diarrhea, infections, rash, fatigue, swelling of hands and feet, abdominal pain, fever, cough, headache, respiratory tract infections, low blood counts, delayed wound healing, abnormal blood sugar or fat levels Severe allergic reactions, kidney damage, inflammation of the lungs
Multi-target kinase inhibitor Stivarga (regorafenib) Skin rash, high blood pressure, delayed wound healing, weakness, fatigue, diarrhea, decreased appetite, infection, voice change or hoarseness, abnormal liver values in the blood, fever; swelling, pain, mouth sores, irritation of throat, stomach, and bowel, weight loss Serious bleeding, severe liver damage, infections, stomach tear, heart attack, brain swelling
Multi-target kinase inhibitor Sutent (sunitinib malate) Fatigue, joint and muscle pain, weakness, fever, diarrhea, nausea, loss of appetite, altered taste, vomiting, stomach pain, indigestion, constipation, high blood pressure, rash, swelling of hands and feet, skin discoloration, dry skin, hair color changes, headache, cough, shortness of breath, bleeding, low blood sugar, low thyroid levels Serious bleeding, severe liver damage, infections, stomach tear, heart attack, severe bone loss of lower jaw
Lynparza ()
Rubraca ()
Talzenna ()
Zejula ()
Nausea, vomiting, diarrhea, change in how food tastes, decreased appetite, weight loss, fatigue or weakness, headache, cough, shortness of breath, dizziness, fever, low blood counts, abdominal pain, urinary tract infections (Lynparza), joint or muscle pain (), fertility problems in men ( Bone marrow damage (myelodysplastic syndrome), acute myeloid leukemia, inflammation of the lungs (Lynparza), blood clots in the lungs (Lynparza), high blood pressure which can become serious ()
PIK3 inhibitor Piqray (alpelisib) Changes in blood tests, decreased appetite, diarrhea, nausea, vomiting, rash, low blood counts,  fatigue, mouth sores, weight loss, hair loss Severe allergic reaction, severe skin reactions, very high blood sugar, severe lung inflammation, severe diarrhea
Targeted chemotherapy Trodelvy (sacituzumab govitecan-hziy) Nausea, low white blood count, constipation, diarrhea, fatigue, anemia, decreased appetite, stomache pain, vomiting, hair loss, rash Severe low white blood counts, severe diarrhea, severe allergic reaction
Tropomysin receptor kinase inhibitor Vitrakvi (larotrectinib) Dizziness, fatigue, constipation, diarrhea, nausea, vomiting, cough, abnormal liver values in the blood Severe nervous system problems, severe liver damage
VEGF inhibitor and VEGF receptor inhibitor

Avastin (bevacizumab)  Zirabev (bevacizumab) 
Cyramza (ramucirumab)

Nose bleeds, headache, high blood pressure, nasal symptoms, too much protein in the urine, taste changes, dry skin, back pain, watery eyes, skin rashes

Very high blood pressure, heart problems, stomach or intestinal tears, fistula (abnormal connection between organs), nonhealing wounds, swelling of the brain
VEGF inhibitor Zaltrap (ziv-aflibercept) 

Nose bleeds, headache, fatigue, weakness, high blood pressure, low blood counts, too much protein in the urine, mouth sores, decreased appetite, diarrhea, back pain, stomach pain, change in voice, changes in kidney function, abnormal liver values in the blood


Very high blood pressure, stomach or intestinal tears, fistula (abnormal connection between organs), nonhealing wounds, swelling of the brain, severe bleeding
VEGF receptor inhibitor Lenvima (lenvatinib) Lenvima when combined with Keytruda (pembrolizumab): fatigue, headache, high blood pressure, joint and muscle pain, constipation, abdominal pain, diarrhea, decreased appetite, nausea and vomiting, low thyroid levels, urinary tract infection, voice changes, bleeding, low magnesemium levels, swelling in hands and feet, cough, trouble breathing, rashes Very high blood pressure, heart problems, stomach or intestinal tears, fistula (abnormal connection between organs), nonhealing wounds, swelling of the brain