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Generic name: lapatinibla-PA-tin-ib ]
Drug classes: EGFR inhibitors, HER2 inhibitors

Medically reviewed by Last updated on May 2, 2022.

What is Tykerb?

Tykerb is a cancer medicine that interferes with the growth and spread of cancer cells in the body.

Tykerb is used to treat a certain type of hormone-related breast cancer that has progressed or spread after treatment with other cancer medicines.

In postmenopausal women, Tykerb is given in combination with a hormonal medicine called Femara (letrozole). In others, Tykerb is given together with a cancer medicine called Xeloda (capecitabine).


Do not use Tykerb if you are pregnant. It could harm the unborn baby.

Tykerb can cause severe or fatal liver problems.

Call your doctor at once if you have signs of liver problems: upper stomach pain, itching, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

Before you take lapatinib, tell your doctor if you have heart disease, liver disease, an electrolyte imbalance (low potassium or magnesium), or a personal or family history of Long QT syndrome.

Take Tykerb on an empty stomach. Take this medication for the entire length of time prescribed by your doctor.

Before taking this medicine

You should not use Tykerb if you are allergic to lapatinib.

To make sure Tykerb is safe for you, tell your doctor if you have:

  • heart disease;

  • liver disease (lapatinib can cause severe or fatal liver problems);

  • an electrolyte imbalance (such as low levels of potassium or magnesium in your blood); or

  • a personal or family history of long QT syndrome.

Do not use Tykerb if you are pregnant. It could harm the unborn baby or cause birth defects. Use effective birth control to prevent pregnancy while you are using this medicine. Tell your doctor right away if you become pregnant.

It is not known whether lapatinib passes into breast milk or if it could harm a nursing baby. You should not breast-feed while you are taking this medicine.

How should I take Tykerb?

Take Tykerb exactly as prescribed by your doctor. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Read all patient information, medication guides, and instruction sheets provided to you. Ask your doctor or pharmacist if you have any questions. Be sure to also read the medication guides for Xeloda or Femara.

When used with Femara, the usual dose of Tykerb is 6 tablets taken once daily every day. Femara is also taken every day.

When used with Xeloda, Tykerb is usually taken in a 21-day cycle. You will take Tykerb in a dose of 5 tablets once daily for all 21 days in a row. You will take Xeloda twice daily for only the first 14 days of the cycle. This 21-day cycle is then repeated.

Your doctor will tell you how much Xeloda or Femara to take. Follow your doctor's dosing instructions very carefully.

Take Tykerb on an empty stomach, at least 1 hour before or 1 hour after a meal.

You may swallow each tablet one at a time, but take the entire dose (all 5 or 6 tablets) at the same time each day.

Xeloda must be taken with food or within 30 minutes of eating.

You will need blood tests every 4 to 6 weeks to check your liver function. Your heart function may also need to be checked using an electrocardiograph or ECG (sometimes called an EKG).

Store at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.

Your doctor will determine how long to treat you with Tykerb and Xeloda or Femara. Take your medications for the full prescribed length of time. Combination chemotherapy is usually continued unless your condition gets worse or you have serious side effects.

Dosing information

Usual Adult Dose for Breast Cancer:

-HER2-POSITIVE METASTATIC BREAST CANCER (in combination with Xeloda): 1250 mg orally once a day on Days 1 to 21 continuously in repeating 21-day cycles until disease progression or unacceptable toxicity.

-HORMONE RECEPTOR-POSITIVE, HER2-POSITIVE METASTATIC BREAST CANCER (in combination with Femara): 1500 mg orally once a day continuously.

-Consult the manufacturer product information for Xeloda and Femara dosing recommendations.
-HER2-positive metastatic breast cancer patients should have disease progression on trastuzumab prior to initiation of treatment with this drug in combination with Xeloda.

-In combination with Xeloda for treatment of patients with advanced or metastatic breast cancer whose tumors overexpress HER2 and who have received prior therapy including an anthracycline, a taxane, and trastuzumab.
-In combination with Femara for treatment of postmenopausal women with hormone receptor-positive metastatic breast cancer that overexpresses the HER2 receptor for whom hormonal therapy is indicated.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What to avoid

Grapefruit and grapefruit juice may interact with lapatinib and lead to unwanted side effects. Avoid the use of grapefruit products while taking Tykerb.

Tykerb side effects

Get emergency medical help if you have signs of an allergic reaction to Tykerb: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Tykerb can cause severe or fatal liver problems. Call your doctor right away if you have: upper stomach pain, itching, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

Also call your doctor at once if you have:

  • a headache with chest pain and severe dizziness, fainting, fast or pounding heartbeats;

  • severe or ongoing diarrhea;

  • new or worsening cough, wheezing, chest pain, feeling short of breath; or

  • severe skin reaction - fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common Tykerb side effects may include:

  • indigestion, loss of appetite;

  • nausea, vomiting, diarrhea;

  • rash, itching, dry skin;

  • pain or redness on the palms of your hands or the soles of your feet;

  • problems with your fingernails or toenails;

  • feeling weak or tired;

  • nosebleeds, mouth sores;

  • thinning hair; or

  • headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Tykerb?

Tell your doctor about all your current medicines and any you start or stop using, especially:

  • an antacid or stomach acid reducer such as Prilosec or Nexium;

  • an antibiotic or antifungal medicine;

  • an antidepressant;

  • heart or blood pressure medication;

  • medicine to treat HIV or AIDS;

  • seizure medication; or

  • St. John's wort.

This list is not complete. Other drugs may interact with lapatinib, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Where can I get more information?

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Tykerb only for the indication prescribed.

Popular FAQ

Tykerb (lapatinib) is a dual tyrosine kinase inhibitor and works by blocking both Epidermal Growth Factor Receptor (EGFR) and human epidermal growth factor receptor 2 (HER-2). This helps stop or slow the spread of breast cancer cells. Continue reading

Further information

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