Lapatinib (Tykerb®)

About This Drug

Lapatinib is used to treat cancer. It is given orally (by mouth).

Possible Side Effects

  • Tiredness
  • Nausea and throwing up (vomiting)
  • Loose bowel movements (diarrhea)
  • Rash
  • Hand-and-foot syndrome. The palms of your hands or soles of your feet may tingle, become numb, painful, swollen, or red.
  • Decrease in red blood cells ( you may feel more tired)
  • Decrease in the number of white blood cells. This may raise your risk of infection.
  • Changes in your liver function

Note: Each of the side effects above was reported in 20% or greater of patients treated with lapatinib. Not all possible side effects are included above.

Warnings and Precautions

  • Severe diarrhea which can be life-threatening
  • Abnormal heart beat and changes in your heart function
  • Inflammation (swelling) of the lungs. You may have a dry cough or trouble breathing.
  • Severe allergic skin reaction which can be life-threatening. You may develop blisters on your skin that are filled with fluid or a severe red rash all over your body that may be painful.
  • Severe changes in your liver function, which can cause liver failure and be life-threatening

Note: Some of the side effects above are very rare. If you have concerns and/or questions, please discuss them with your medical team.

Important Information

  • It is important that you notify your doctor and/or nurse at the first sign of loose bowel movements (diarrhea) so they can provide you with anti-diarrhea medication and give you further instructions. Notify your doctor and/or nurse if you are taking anti-diarrhea medication and your symptoms have not improved, or are worsening.

How to Take Your Medication

  • Take this drug by mouth without food, at least 1 hour before you eat or 1 hour after you eat.
  • Missed dose: If you vomit or miss a dose, take your next dose at the regular time, and contact your physician. Do not take 2 doses at the same time and do not double up on the next dose.
  • Handling: Wash your hands after handling your medicine; your caretakers should not handle your medicine with bare hands and should wear latex gloves.
  • Storage: Store this medicine in the original container at room temperature. Discuss with your nurse or your doctor how to dispose of unused medicine.

Treating Side Effects

  • Drink plenty of fluids (a minimum of eight glasses per day is recommended).
  • If you throw up or have loose bowel movements, you should drink more fluids so that you do not become dehydrated (lack water in the body from losing too much fluid).
  • If you get diarrhea, eat low-fiber foods that are high in protein and calories and avoid foods that can irritate your digestive tracts or lead to cramping.
  • Ask your nurse or doctor about medicine that can lessen or stop your diarrhea.
  • To help with nausea and vomiting, eat small, frequent meals instead of three large meals a day. Choose foods and drinks that are at room temperature. Ask your nurse or doctor about other helpful tips and medicine that is available to help or stop lessen these symptoms.
  • If you get a rash do not put anything on it unless your doctor or nurse says you may. Keep the area around the rash clean and dry. Ask your doctor for medicine if your rash bothers you.
  • Avoid sun exposure and apply sunscreen routinely when outdoors.
  • Manage tiredness by pacing your activities for the day.
  • Be sure to include periods of rest between energy-draining activities.
  • To decrease infection, wash your hands regularly.
  • Avoid close contact with people who have a cold, the flu, or other infections.
  • Take your temperature as your doctor or nurse tells you, and whenever you feel like you may have a fever.

Food and Drug Interactions

  • Do not eat grapefruit or drink grapefruit juice while taking this medicine.Grapefruit and grapefruit juice may raise the levels of lapatinib in your body. This could make side effects worse.
  • Check with your doctor or pharmacist about all other prescription medicines and over-the-counter medicines and dietary supplements (vitamins, minerals, herbs and others) you are taking before starting this medicine as there are known drug interactions with lapatinib . Also, check with your doctor or pharmacist before starting any new prescription or over-the-counter medicines, or dietary supplement to make sure that there are no interactions.
  • Avoid the use of St. John’s Wort while taking lapatinib as this may lower the levels of the drug in your body, which can make it less effective.

When to Call the Doctor

Call your doctor or nurse if you have any of these symptoms and/or any new or unusual symptoms:

  • Fever of 100.5 F (38 C) or higher
  • Chills
  • Fatigue that interferes with your daily activities.
  • Feeling dizzy or lightheaded
  • Feeling that your heart is beating in a fast or not normal way (palpitations)
  • Pain in your chest
  • Trouble breathing
  • Dry cough
  • Flu-like symptoms: fever, headache, muscle and joint aches, and fatigue (low energy, feeling weak)
  • Loose bowel movements (diarrhea) 4 times a day or loose bowel movements with lack of strength or a feeling of being dizzy
  • Nausea that stops you from eating or drinking and/or is not relieved by prescribed medicines
  • Throwing up more than 3 times a day
  • Swelling of legs, ankles, or feet
  • Weight gain of 5 pounds in one week (fluid retention)
  • Signs of possible liver problems: dark urine, pale bowel movements, bad stomach pain, feeling very tired and weak, unusual itching, or yellowing of the eyes or skin
  • New rash and/or itching
  • Rash that is not relieved by prescribed medicines
  • Painful, red, or swollen areas on your hands or feet.
  • Numbness and/or tingling of your hands and/or feet
  • If you think you may be pregnant

Reproduction Warnings

  • Pregnancy warning: This drug can have harmful effects on the unborn baby. Women of childbearing potential should use effective methods of birth control during your cancer treatment. Let your doctor know right away if you think you may be pregnant.
  • Breastfeeding warning: It is not known if this drug passes into breast milk. For this reason, women should talk to their doctor about the risks and benefits of breastfeeding during treatment with this drug because this drug may enter the breast milk and cause harm to a breastfeeding baby.
  • Fertility warning: Human fertility studies have not been done with this drug. Talk with your doctor or nurse if you plan to have children.Ask for information on sperm or egg banking.

Revised February 2018

This information is intended to provide helpful health information to the general public and is not to be used in place of any medical, health, psychological, or any other kind of personal professional services. The information herein does not cover all possible uses, actions, precautions, side effects, or interactions of the medicines mentioned, nor is the information intended as medical advice for individual problems or for making an evaluation as to the risks and benefits of taking a particular medication. The dose, method of administration and contraindications for any administered medication should be confirmed before use. UPMC specifically disclaims all responsibility for any liability, loss or risk, personal or otherwise, which is incurred as a consequence, directly or indirectly, of the use and application of any medication mentioned herein.