Lapatinib | Side Effects, Dosage, Uses & More

Generic Name:

lapatinib, Oral tablet

All Brands

  • Tykerb
SECTION 1 of 5

Highlights for lapatinib

Oral tablet
1

Lapatinib is an oral drug that’s used to treat breast cancer. It’s used in combination with capecitabine or letrozole.

2

The standard dose is 1,250–1,500 mg taken once per day at least one hour before or after eating a meal. Your dose depends on the type of breast cancer that you have. Your doctor will tell you the dose that’s right for you.

3

Lapatinib may cause severe or life-threatening liver damage. Tell your doctor if you have a history of liver disease.

4

Lapatinib can decrease how much blood is pumped by your heart. It can also cause an irregular heartbeat that can be life-threatening. Your doctor should check your heart function before starting and during treatment with lapatinib.

5

Common side effects include stomach problems, skin and nail problems, mouth sores, headache, and nosebleeds.

IMPORTANT INFORMATION

FDA warning

This drug has a Black Box Warning. This is the most serious warning from the Food and Drug Administration (FDA). A black box warning alerts doctors and patients to potentially dangerous effects.

Liver damage warning. Lapatinib may cause severe or life-threatening liver damage. Tell your doctor if you have or have ever had liver disease. Call your doctor right away if you have any symptoms of liver problems, such as:

  • itching
  • yellowing of your skin or the whites of your eyes
  • dark-colored urine
  • pain in the upper part of the stomach
  • unusual bleeding or bruising
  • pale or dark-colored stools

Heart problems

Lapatinib can cause the following heart issues. Your doctor should check your heart function before starting and during treatment with lapatinib:

  • decreased pumping of blood from your heart
  • abnormal heart rate. This drug can cause long QT syndrome, which is a dangerous, life-threatening condition. Symptoms include:
    • feeling like your heart is pounding or racing
    • dizziness
    • tiredness
    • lightheadedness
    • shortness of breath
  • changes in the electrical activity of your heart. Your risk may be higher if:
    • your magnesium and potassium levels are too low
    • you’re taking certain medications to treat an abnormal heart rhythm
    • you’re taking high doses of anthracycline therapy, a type of medication used to treat cancer

Diarrhea

This drug may cause diarrhea. Severe diarrhea can cause you to lose too much body fluid and can be life threatening. Call your doctor right away if you have a change in your bowel habits or if you have severe diarrhea.

Drug features

Lapatinib is a prescription drug. It’s available as an oral tablet. It is not available as a generic drug.

Lapatinib may be used as part of a combination therapy with capecitabine or letrozole. That means you need to take it with other drugs.

Why it's used

Lapatinib is used to treat breast cancer. Specifically, it’s used in combination with:

  • capecitabine to treat advanced or metastatic breast cancer that is HER2-positive (a protein in your body). It’s used in people who’ve had certain other breast cancer treatments.
  • letrozole to treat hormone receptor-positive, HER2-positive metastatic breast cancer in postmenopausal women who need hormonal therapy.

How it works

Lapatinib belongs to a drug class called kinase inhibitors. A class of drugs refers to medications that work similarly. They have a similar chemical structure and are often used to treat similar conditions.

Lapatinib works by blocking the action of the abnormal protein kinase that tells cancer cells in your body to multiply. This helps stop or slow the spread of cancer cells in your body.

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SECTION 2 of 5

lapatinib Side Effects

Oral tablet

Most Common Side Effects

The most common side effects that occur with lapatinib include:

  • stomach problems, such as:

    • diarrhea
    • nausea
    • vomiting
    • loss of appetite
    • heartburn
  • skin and nail problems, such as:

    • dry skin
    • red, painful palms and soles
    • itching
    • painful, red, and swollen area around your nails
    • nail pain
    • infection and swelling of your cuticles
    • unusual hair loss or thinning
  • mouth sores

  • tiredness or weakness

  • nosebleeds

  • headache

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious Side Effects

If you experience any of these serious side effects, call your doctor right away. If your symptoms are potentially life threatening, or if you think you’re experiencing a medical emergency, call 9-1-1.

  • Abnormal heart rate. Symptoms include:

    • feeling like your heart is pounding or racing
    • dizziness
    • tiredness
    • lightheadedness
    • shortness of breath
  • Liver problems. Symptoms include:

    • itching
    • yellowing of your skin or the whites of your eyes
    • dark-colored urine
    • pain in the upper part of your stomach
    • unusual bleeding or bruising
    • pale or dark-colored stools
  • Severe diarrhea

  • Lung problems. Symptoms include:

    • cough that won’t go away
    • shortness of breath
  • Severe skin reactions. Symptoms include:

    • skin rash
    • blisters
    • peeling of your skin
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Lapatinib doesn’t cause drowsiness.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
SECTION 3 of 5

lapatinib May Interact with Other Medications

Oral tablet

Lapatinib can interact with other medications, herbs, or vitamins you might be taking. That’s why your doctor should manage all of your medications carefully. If you’re curious about how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Note: You can reduce your chances of drug interactions by having all of your prescriptions filled at the same pharmacy. That way, a pharmacist can check for possible drug interactions.

Medications that might interact with this drug

Drugs that cause sedation
  • midazolam

This drug when taken with lapatinib will increase your risk of side effects. Your doctor may lower your dose of midazolam if you’re using it with lapatinib.

Cancer drugs
  • paclitaxel

This drug when taken with lapatinib will increase your risk of side effects. Your doctor may lower your dose of the medication if you’re using it with lapatinib.

Heart drugs
  • digoxin

This drug when taken with lapatinib will increase your risk of side effects. Your doctor may lower your dose of the medication if you’re using it with lapatinib.

Drugs to treat fungal infections
  • ketoconazole

This drug when taken with lapatinib will increase your risk of side effects. Your doctor may lower your dose of the medication if you’re using it with lapatinib.

Drug to treat seizures
  • carbamazepine

Using these drugs together will decrease the effect of lapatinib. Your doctor may increase your dose of lapatinib.

Drugs that change drug transporting systems

Examples are:

  • propranolol
  • pravastatin
  • quinidine
  • ranitidine
  • risperidone

These drugs, when taken with lapatinib, will increase your risk of side effects. Your doctor may lower your dose of the medication if you’re using it with lapatinib.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

People with liver problems

Lapatinib may cause severe or life-threatening liver damage. If you have decreased liver function, your doctor may start you on a lower dose than normal.

People with heart problems

Lapatinib can cause heart problems and make existing heart conditions worse, such as heart failure or congenital long QT syndrome.

Pregnant women

Lapatinib is a category D pregnancy drug. That means two things:

  1. Research in humans has shown adverse effects to the fetus when the mother takes the drug.
  2. This drug should only be used during pregnancy in serious cases where it's needed to treat a dangerous condition in the mother.

Talk to your doctor if you’re pregnant or planning to become pregnant. Ask your doctor to tell you about the specific harm that may be done to the fetus. This drug should be only used if the potential risk to the fetus is acceptable given the drug’s potential benefit.

Women who are breast-feeding

It isn’t known if lapatinib goes into breast milk. If it does, it may cause serious effects in a breastfeeding child.

You and your doctor may need to decide if you’ll take lapatinib or breastfeed.

For seniors

Older adults may process this medication more slowly. Because of this, your doctor may monitor you more closely while taking lapatinib.

For children

The safety and effectiveness of lapatinib haven’t been established in people under the age of 18 years.

Allergies

Lapatinib can cause a severe allergic reaction. Symptoms may include:

  • trouble breathing
  • swelling of your throat or tongue
  • hives

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal.

SECTION 4 of 5

How to Take lapatinib (Dosage)

Oral tablet

All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Breast cancer

Brand: Tykerb

Form: Oral tablet
Strengths: 250 mg
Adult dosage (ages 18–64 years)
  • HER2-positive metastatic breast cancer:
    • This medication will be taken in 21-day cycles in combination with capecitabine.
    • The standard dose is 1,250 mg (5 tablets) taken once per day on days 1–21 in combination with capecitabine. The next cycle starts after the first. This continues until the condition stops improving and instead progresses, or if you can’t tolerate the side effects. Then your doctor will find a different medication.
    • Lapatinib should be taken at least one hour before or one hour after eating a meal.
    • Your dose of lapatinib should be taken all at once (5 tablets).
  • Hormone receptor-positive, HER2-positive metastatic breast cancer:
    • This medication will be taken in combination with letrozole.
    • The standard dose is 1,500 mg (6 tablets) once per day continuously in combination with letrozole
    • Lapatinib should be taken at least one hour before or one hour after eating a meal.
    • Your dose of lapatinib should be taken all at once (6 tablets).
Child dosage (ages 0–17 years)

This medicine hasn’t been studied in children and shouldn’t be used in people younger than 18 years.

Senior dosage (ages 65 years and older)

Older adults may process drugs more slowly. A normal adult dose may cause levels of this drug to be higher than normal in your body. Your doctor may lower your dose or have you take this drug on a different schedule.

Special considerations

Liver problems: If you have severe liver problems (Child-Pugh class C), you may start on a lower dose:

  • HER2-positive metastatic breast cancer: 750 mg taken once per day
  • Hormone receptor-positive, HER2-positive metastatic breast cancer: 1,000 mg taken once per day

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Lapatinib comes with serious risks if you don’t take it as prescribed.

If you don’t take it at all

Your cancer may get worse and spread to other parts of your body. This can be fatal.

If you skip or miss doses

You may not get the full benefit of this medication to treat your breast cancer.

If you take too much

You may have more side effects, such as abnormal heart rate, liver problems, severe diarrhea, lung problems, or severe skin reactions. If you think you’re having a medical emergency, call your doctor or go to the emergency room.

What to do if you miss a dose

If you forget to take your dose, take it as soon as you remember. If it’s just a few hours before the time for your next dose, take only one dose at that time.

Never try to catch up by taking two doses at once. This could result in toxic side effects.

How to tell if the drug is working

You may be able to tell if this drug is working if your symptoms caused by breast cancer get better. Your doctor will also do tests to check if this drug is working.

Lapatinib is a long-term drug.

You should take this medication with food

Your body will absorb lapatinib better when taken with food.

Take this drug at the right time for best effects

Lapatinib should be taken at least one hour before or one hour after eating a meal.

Store lapatinib at 77°F (25°C)

This medication can be stored from 59–86°F (15–30°C) for a short time.

Keep this drug away from light and high temperature.

Keep your drugs away from areas where they could get wet, such as bathrooms. Store this drug away from moisture and damp locations.

Travel

Always carry your medication with you. Don’t worry about airport x-ray machines. They can’t hurt this medication. You may need to show your pharmacy’s label to clearly identify the medication. Keep the original prescription label with you when traveling with your medication. Don’t leave this medicine in the car, especially when the temperature is hot or freezing. Make sure that you have enough medication before you travel. This drug may not be available at every pharmacy.

Clinical monitoring

Your doctor may do tests. Before starting and during treatment with lapatinib, your doctor may check your:

  • liver function
  • electrolyte levels
  • heart function
  • lung function

Insurance

Many insurance companies will require a prior authorization before they approve the prescription and pay for lapatinib.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be more suitable for you than others. Talk to your doctor about possible alternatives.

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How Much Does lapatinib Cost?

Oral tablet

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Lowest price for lapatinib

Kroger Pharmacy $1,196.34
Target (CVS) $1,225.24
Walgreens $1,230.39
These prices represent the lowest priced national pharmacies for lapatinib on GoodRx. They may be lower than your insurance.

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These prices represent the lowest priced national pharmacies for lapatinib on GoodRx. They may be lower than your insurance.

Show Sources

Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on August 18, 2015

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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