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Generic Name: Ado-Trastuzumab Emtansine (a do tras TU zoo mab em TAN seen)
Brand Name: Kadcyla

Medically reviewed by Last updated on Nov 8, 2020.


  • Very bad and sometimes deadly liver problems have happened with Kadcyla (ado-trastuzumab emtansine). Call your doctor right away if you have signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • This medicine may cause heart failure. You will need to have your heart function checked while taking Kadcyla (ado-trastuzumab emtansine). Call your doctor right away if you have signs of heart problems like a cough or shortness of breath that is new or worse, swelling of the ankles or legs, a heartbeat that does not feel normal, weight gain of more than 5 pounds in 24 hours, dizziness, or passing out.
  • This medicine may cause harm to the unborn baby or loss of the unborn baby if you take it while you are pregnant or if you get pregnant within 7 months after your last dose.
  • Use birth control that you can trust to prevent pregnancy while taking Kadcyla (ado-trastuzumab emtansine) and for at least 7 months after stopping Kadcyla (ado-trastuzumab emtansine).
  • If you get pregnant while taking Kadcyla (ado-trastuzumab emtansine) or within 7 months after your last dose, call your doctor right away.

Uses of Kadcyla:

What do I need to tell my doctor BEFORE I take Kadcyla?

  • If you have an allergy to ado-trastuzumab emtansine or any other part of Kadcyla (ado-trastuzumab emtansine).
  • If you are allergic to Kadcyla (ado-trastuzumab emtansine); any part of Kadcyla (ado-trastuzumab emtansine); or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
  • If you are taking any of these drugs: Atazanavir, clarithromycin, indinavir, itraconazole, ketoconazole, nefazodone, nelfinavir, ritonavir, saquinavir, or telithromycin.
  • If you are taking voriconazole.
  • If you are breast-feeding. Do not breast-feed while you take Kadcyla (ado-trastuzumab emtansine) or within 7 months after you stop taking it.

This is not a list of all drugs or health problems that interact with Kadcyla (ado-trastuzumab emtansine).

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take Kadcyla (ado-trastuzumab emtansine) with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take Kadcyla?

  • Tell all of your health care providers that you take Kadcyla (ado-trastuzumab emtansine). This includes your doctors, nurses, pharmacists, and dentists.
  • You may bleed more easily. Be careful and avoid injury. Use a soft toothbrush and an electric razor. Rarely, some bleeding problems have been deadly.
  • Some people have side effects during the infusion. These include chills, fast heartbeat, fever, flushing, shortness of breath, very bad dizziness or passing out, and wheezing. You will be watched closely during the infusion and for some time after. Tell your doctor if you have any of these side effects or any other effects during the infusion.
  • Low white blood cell counts have happened with Kadcyla (ado-trastuzumab emtansine). This may lead to a higher chance of getting an infection. Call your doctor right away if you have signs of infection like fever, chills, or sore throat.
  • If you are able to get pregnant, a pregnancy test will be done to show that you are NOT pregnant before starting Kadcyla (ado-trastuzumab emtansine). Talk with your doctor.
  • This medicine may affect fertility. Fertility problems may lead to not being able to get pregnant or father a child.
  • Men with a partner who may get pregnant must use birth control while taking Kadcyla (ado-trastuzumab emtansine) and for some time after the last dose. Ask your doctor how long to use birth control. If your partner gets pregnant, call the doctor right away.

How is this medicine (Kadcyla) best taken?

Use Kadcyla (ado-trastuzumab emtansine) as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • It is given as an infusion into a vein over a period of time.

What do I do if I miss a dose?

  • Call your doctor to find out what to do.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of bleeding like throwing up or coughing up blood; vomit that looks like coffee grounds; blood in the urine; black, red, or tarry stools; bleeding from the gums; abnormal vaginal bleeding; bruises without a cause or that get bigger; or bleeding you cannot stop.
  • Signs of a urinary tract infection (UTI) like blood in the urine, burning or pain when passing urine, feeling the need to pass urine often or right away, fever, lower stomach pain, or pelvic pain.
  • Signs of low potassium levels like muscle pain or weakness, muscle cramps, or a heartbeat that does not feel normal.
  • Weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight.
  • A burning, numbness, or tingling feeling that is not normal.
  • Feeling very tired or weak.
  • Some people have had lung problems with Kadcyla (ado-trastuzumab emtansine). Sometimes, this has been deadly. Call your doctor right away if you have signs of lung problems like shortness of breath or other trouble breathing, cough that is new or worse, or fever.
  • This medicine may irritate the vein. If the drug leaks from the vein, it may also cause irritation around that area. Tell your nurse if you have any redness, burning, pain, swelling, or leaking of fluid where the drug is going into your body.

What are some other side effects of Kadcyla?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Dry mouth.
  • Stomach pain or heartburn.
  • Feeling dizzy, tired, or weak.
  • Muscle or joint pain.
  • Headache.
  • Nosebleed.
  • Trouble sleeping.
  • Rash.
  • Mouth irritation or mouth sores.
  • Constipation, diarrhea, throwing up, and upset stomach are common with Kadcyla (ado-trastuzumab emtansine). If these happen, talk with your doctor about ways to lower these side effects. Call your doctor right away if any of these effects bother you, do not go away, or get very bad.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

If OVERDOSE is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out Kadcyla?

  • If you need to store Kadcyla (ado-trastuzumab emtansine) at home, talk with your doctor, nurse, or pharmacist about how to store it.

Consumer information use

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else's drugs.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.
  • Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about Kadcyla (ado-trastuzumab emtansine), please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.