Lapatinib | Side Effects, Dosage, Uses & More
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Generic Name:

lapatinib, Oral tablet

All Brands

  • Tykerb
SECTION 1 of 5

Highlights for lapatinib

Oral tablet
1

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

2

Lapatinib comes as a tablet that you take by mouth.

3

Lapatinib is available as the brand-name drug Tykerb. It’s not available as a generic drug.

IMPORTANT INFORMATION

Food and Drink Administration 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. This drug may cause severe liver damage. This can be fatal (cause death). 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 urine
  • pain in the upper part of your abdomen
  • unusual bleeding or bruising
  • pale or dark-colored stools

Heart problems

This drug can cause heart issues. Your doctor should check your heart function before  and during your treatment with this drug. These heart issues can include:

  • Decreased pumping of blood
  • Abnormal heart rate or long QT syndrome, which can be fatal (cause death). Symptoms can include:
    • pounding heartbeat
    • fast heart rate
    • 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

Severe diarrhea

This drug may cause diarrhea. Severe diarrhea can cause you to lose too much body water. This can be fatal (cause death). Call your doctor right away if you have severe diarrhea.

What is lapatinib?

This drug is a prescription drug. It comes as a tablet you take by mouth.

This drug is available as the brand-name drug Tykerb. It is not available as a generic drug.

This drug may be used as part of a combination therapy. That means you may need to take it with other drugs to treat your condition. This drug may be prescribed with capecitabine or letrozole.

Why it's used

This drug is used to treat breast cancer. It’s used with a drug called capecitabine to treat advanced or metastatic breast cancer that is HER2-positive (has a protein in your body). It’s used when certain other breast cancer treatments have not worked. It’s also used with a drug called letrozole to treat hormone receptor-positive, HER2-positive metastatic breast cancer in postmenopausal women who need hormonal therapy.

How it works

This drug belongs to a drug class called kinase inhibitors. A class of drugs refers to medications that work in a similar way. These drugs are often used to treat similar conditions.

This drug works by blocking the action of certain proteins called kinases that tell cancer cells in your body to multiply. This action helps slow or stop 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

Call your doctor right away if you have serious side effects. Call 9-1-1 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • 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
Clinical Associate Professor, University of Illinois at Chicago College of Pharmacy

This drug 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, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

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.
Drug warnings
liver problem warning
People with liver problems

This drug may cause severe liver damage that may be fatal (cause death). If you already have decreased liver function, your doctor may start you on a reduced dosage.

heart problem warning
People with heart problems

This drug can cause heart problems and worsen existing heart conditions such as heart failure or congenital long QT syndrome.

pregnancy warning
Pregnant women

This drug 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 only be used if the potential risk to the fetus is acceptable given the drug’s potential benefit.

breast feeding warning
Women who are breast-feeding

It isn’t known if this drug passes into breast milk. If it does, it may cause serious effects in a child who is breastfed.

Talk to your doctor about breastfeeding your child. You may need to decide whether to stop breastfeeding or stop taking this medication.

senior warning
For seniors

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects. Your doctor may monitor you more closely while taking this drug.

childrens warning
For children

This drug hasn’t been established as safe and effective for use in people younger than 18 years.

call the doctor
When to call the doctor

Call your doctor if you become pregnant while taking this drug.

allergy warning
Allergies

This drug can cause a severe allergic reaction. Symptoms can include:

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

If you have an allergic reaction, call your doctor or local poison control center right away. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room.

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

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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
Strength: 250 mg
Adult dosage (ages 18–64 years)
  • For treating HER2-positive metastatic breast cancer:
    • The typical dosage is 1,250 mg (five tablets) taken once per day in combination with capecitabine. This continues until the condition stops improving or if you can’t tolerate the side effects. Then your doctor will likely prescribe a different medication.
  • For treating hormone receptor-positive, HER2-positive metastatic breast cancer:
    • The typical dosage is 1,500 mg (6 tablets) once per day in combination with letrozole
Child dosage (ages 0–17 years)

This drug should not be used in people younger than 18 years.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

Your doctor may start you on a lowered dose or a different dosing schedule. This can help keep levels of this drug from building up too much in your body.

Special considerations

People with severe liver problems: Your doctor may start you on a lower dosage.

  • For HER2-positive metastatic breast cancer: 750 mg taken once per day
  • For 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
Clinical Associate Professor, University of Illinois at Chicago College of Pharmacy

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

If you stop taking the drug suddenly or 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 miss doses or don’t take the drug on schedule

Your medication may not work as well or may stop working completely. For this drug to work well, a certain amount needs to be in your body at all times.

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’ve taken too much of this drug, call your doctor or local poison control center. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room right away.

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. Doing so could result in harmful side effects.

How to tell if the drug is working

The symptoms of your breast cancer may get better. You may not be able to feel that the drug is working, though. Your doctor will do tests to check if this drug is working for you.

This drug is used for long-term treatment.

Important considerations for taking this drug
take with food
Take this medication with food. Your body will absorb this drug better when you take it with food
timing considerations
Take this drug at least one hour before or after eating
storage considerations
Store this drug carefully
See Details
 medication is refillable
A prescription for this medication is refillable
See Details
travel considerations
Travel
See Details
clinical monitoring considerations
Clinical monitoring
See Details
not usually stocked
Not every pharmacy stocks this drug. When filling your prescription, be sure to call ahead
prior authorization needed
Insurance
See Details

Store this drug carefully

  • Store this drug at 77°F (25°C). This medication can be stored at temperatures between 59°F  and 86°F (15°C and 30°C) for a short time.
  • Keep this drug away from light.
  • Don’t store this medication in moist or damp areas, such as bathrooms.

A prescription for this medication is refillable

You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled box with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.
  • Make sure that you have enough medication before you travel. This drug may not be available at every pharmacy.

Clinical monitoring

Your doctor should monitor certain health issues before and during your treatment. This can help make sure you stay safe while you take this drug. These issues include your:

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

Insurance

Many insurance companies require a prior authorization for this drug. This means your doctor may need to get approval from your insurance company before your insurance company will pay for the prescription.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

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How Much Does lapatinib Cost?

Oral tablet

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Lowest price for lapatinib

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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

  • GlaxoSmithKline. (2014, December). Tykerb (lapatinib) tablets, for oral use [package insert]. Research Triangle Park, NC.

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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