Tykerb (lapatinib) has potential interactions with other medications and some supplements. These interactions could affect how well the drug works or cause harmful effects.
Tykerb is used in adults to treat HER-2 positive breast cancer that’s advanced or metastatic (has spread to other parts of the body).
An interaction can occur because one substance causes another substance to have a different effect than expected. Interactions can also occur if you have certain health conditions. Keep reading to learn about Tykerb’s possible interactions.
Boxed warning: Risk of liver damage
Tykerb has a boxed warning about the risk of liver damage. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). It alerts doctors and patients about drug effects that may be dangerous.
Tykerb may rarely cause severe liver damage. In some people, this damage may be life threatening. Your doctor will regularly check your liver function while you are taking Tykerb. If you develop severe liver problems, your doctor will likely stop your Tykerb treatment.
For more information on this warning, talk with your doctor or pharmacist.
Before you start taking Tykerb, tell your doctor and pharmacist about any prescription, over-the-counter, or other drugs you take. Sharing this information with them may help prevent possible interactions.
To learn whether Tykerb interacts with herbs, vitamins, or supplements, see the “Are there other interactions with Tykerb?” section.
If you have questions about drug interactions that may affect you, talk with your doctor or pharmacist.
The following table lists drugs that may interact with Tykerb. Keep in mind this table does not include all drugs that may interact with Tykerb. For more information about some of these interactions, see the “Drug interactions explained” section.
| Drug group or drug name | Drug examples | What can happen |
| certain antifungals | • itraconazole (Sporanox, Tolsura) • ketoconazole • voriconazole (Vfend) | can increase the risk of side effects from Tykerb |
| certain antibiotics | • ciprofloxacin (Cipro) • clarithromycin • rifampin (Rifadin, Rimactane) | can increase the risk of side effects from Tykerb or make Tykerb less effective |
| certain HIV medications | • atazanavir (Reyataz) • nelfinavir (Viracept) • ritonavir (Norvir) | can increase the risk of side effects from Tykerb |
| certain seizure medications | • carbamazepine (Tegretol, others) • phenobarbital (Sezaby) • phenytoin (Dilantin, Phenytek) | can make Tykerb less effective |
| certain antidepressants | • citalopram (Celexa) • escitalopram (Lexapro) • nefazodone | can increase the risk of side effects from Tykerb |
| certain antipsychotics | • aripiprazole (Abilify, Opipza) • haloperidol (Haldol) • risperidone (Risperdal) | can increase the risk of side effects from Tykerb and certain antipsychotics |
| certain heart medications | • amiodarone (Pacerone) • digoxin (Lanoxin) • verapamil (Verelan) | can increase the risk of side effects from Tykerb and certain heart medications |
| dexamethasone | — | can make Tykerb less effective |
Certain health conditions or other factors could increase your risk of harm if you take Tykerb. These are known as contraindications. In such cases, your doctor may not prescribe this medication for you. Tykerb has one contraindication, which is a previous allergic reaction.
If you’ve had an allergic reaction to Tykerb or any of its ingredients, your doctor likely won’t prescribe this medication for you. Ask them about other treatments that may be better options.
Tykerb is not known to interact with alcohol. But Tykerb and alcohol can cause some similar side effects, such as nausea, diarrhea, and headache. So you may be more likely to experience these side effects if you drink alcohol during your Tykerb treatment.
Drinking large amounts of alcohol can also damage your liver. Tykerb has a boxed warning about the risk of liver damage. For more information about this, see the boxed warning at the start of this article. You may have a raised risk of liver damage if you drink alcohol with Tykerb.
If you have questions about consuming alcohol while taking Tykerb, talk with your doctor or pharmacist.
Learn more about certain drug interactions that can occur with Tykerb.
Interaction with certain antibiotics
Tykerb can interact with certain antibiotics, which are used to treat bacterial infections.
Taking Tykerb with some antibiotics can make Tykerb build up in your body. This can raise your risk of side effects from Tykerb, such as abnormal heart rhythms. Some antibiotics can also cause abnormal heart rhythms. Taking Tykerb with these antibiotics can raise your risk of this side effect.
Here are some antibiotics that can increase your risk of side effects from Tykerb:
- ciprofloxacin (Cipro)
- clarithromycin
- levofloxacin
Taking Tykerb with some other antibiotics can make your body break down Tykerb faster than usual. This can make Tykerb less effective.
Here are some antibiotics that can make Tykerb less effective:
- rifabutin (Mycobutin)
- rifampin (Rifadin, Rimactane)
- rifapentine (Priftin)
What you can do
Your doctor will usually avoid prescribing antibiotics that can interact with Tykerb during your Tykerb treatment.
If your doctor prescribes an antibiotic that can raise your risk of Tykerb side effects, your doctor may lower your dosage of Tykerb, or they may monitor you more closely. You should not take a higher dose of either medication than your doctor prescribes.
If you take Tykerb with one of these antibiotics, tell your doctor right away if you have symptoms of abnormal heart rhythms. These may include heart palpitations, dizziness, and fainting.
If you take Tykerb with an antibiotic that can make Tykerb less effective, your doctor may prescribe a dosage of Tykerb that’s higher than usual. You should not take a higher dose of either medication than your doctor prescribes.
If you have questions about taking Tykerb with antibiotics, talk with your doctor or pharmacist.
Interaction with certain antidepressants
Taking Tykerb with certain antidepressants can make Tykerb build up in your body. This can raise your risk of side effects from Tykerb, such as abnormal heart rhythms. Some antidepressants can also cause abnormal heart rhythms. Taking Tykerb with these antidepressants can raise your risk of this side effect.
Here are some antidepressants that may interact with Tykerb:
- citalopram (Celexa)
- clomipramine (Anafranil)
- escitalopram (Lexapro)
- nefazodone
If you take Tykerb with one of these antidepressants, you may have a higher risk of abnormal heart rhythms if you have an electrolyte imbalance, such as a low potassium or magnesium level.
What you can do
If you take Tykerb with certain antidepressants, your doctor may prescribe a dosage of Tykerb that’s lower than usual. You should not take a higher dose of either medication than your doctor prescribes.
If you take Tykerb and one of these antidepressants together, your doctor may monitor you more closely. For example, they may order blood tests to check your electrolyte levels and electrocardiograms (ECGs) to check your heart rhythm.
Tell your doctor right away if you have symptoms of abnormal heart rhythms. These may include heart palpitations, dizziness, and fainting.
If you have questions about taking Tykerb with antidepressants, talk with your doctor or pharmacist.
Interaction with certain heart medications
Tykerb can interact with certain heart medications, which are used to treat conditions such as irregular heartbeats and heart failure.
Here are some heart medications that may interact with Tykerb:
- antiarrhythmic drugs, such as amiodarone (Pacerone), dronedarone (Multaq), or flecainide
- digoxin (Lanoxin)
- verapamil (Verelan)
Taking Tykerb with antiarrhythmic drugs such as amiodarone can raise your risk of abnormal heart rhythms. This is a side effect of both Tykerb and antiarrhythmics. You may have a higher risk of abnormal heart rhythms if you have an electrolyte imbalance, such as a low potassium or magnesium level.
Taking Tykerb with digoxin can make digoxin build up in your body. This can raise your risk of side effects from digoxin.
Taking Tykerb with verapamil can make Tykerb or verapamil build up in your body. This can raise your risk of side effects from either medication.
What you can do
If you take Tykerb and an antiarrhythmic drug together, your doctor may monitor you more closely. For example, they may order blood tests to check your electrolyte levels and ECGs to check your heart rhythm. Tell your doctor right away if you have symptoms of abnormal heart rhythms. These may include heart palpitations, dizziness, and fainting.
If you take Tykerb with digoxin, your doctor may prescribe a dosage of digoxin that’s lower than usual. You should not take a higher dose of either medication than your doctor prescribes. Your doctor will monitor you closely if you take these medications together.
If you take Tykerb with verapamil, your doctor may prescribe a dosage of Tykerb or verapamil that’s lower than usual. You should not take a higher dose of either medication than your doctor prescribes. Your doctor will monitor you closely if you take these medications together.
If you have questions about taking Tykerb with heart medications, talk with your doctor or pharmacist.
Tykerb may have other interactions. They could occur with supplements, foods, vaccines, or even lab tests.
Here are additional interactions that may occur with Tykerb. Note that this is not a full list of all other possible interactions with Tykerb.
Does Tykerb interact with supplements?
Before you start taking Tykerb, talk with your doctor and pharmacist about any herbs, vitamins, or supplements you take. Sharing this information with them may help you avoid possible interactions.
If you have questions about interactions that may affect you, talk with your doctor or pharmacist.
Tykerb interactions with herbs
Tykerb can interact with St. John’s wort, which is used to treat depression and other conditions.
Taking St. John’s wort with Tykerb can make your body break down Tykerb faster than usual. This can make Tykerb less effective. Because of this, your doctor will likely recommend that you avoid taking St. John’s wort with Tykerb.
Tykerb interactions with vitamins
There are currently no reports of Tykerb interacting with vitamins. But this doesn’t mean that vitamin interactions won’t be recognized in the future.
For this reason, it’s important to check with your doctor or pharmacist before taking any of these products while taking Tykerb.
Does Tykerb interact with food?
Consuming grapefruit or grapefruit juice while taking Tykerb can make Tykerb build up in your body. This can raise your risk of side effects from Tykerb. You should avoid consuming grapefruit and grapefruit juice while taking Tykerb.
It’s important to note that you should not eat food at least 1 hour before and 1 hour after taking Tykerb. If you take Tykerb with food, the interaction could decrease the level of the drug in your body. This may make Tykerb less effective.
Does Tykerb interact with vaccines?
There are currently no reports of Tykerb interacting with vaccines. If you have questions about getting certain vaccines during your Tykerb treatment, talk with your doctor.
Does Tykerb interact with lab tests?
There are currently no reports of Tykerb interacting with lab tests. If you have questions about having certain lab tests during your treatment with Tykerb, talk with the healthcare professional ordering the test.
Does Tykerb interact with cannabis or CBD?Cannabis (commonly called marijuana) and cannabis products, such as cannabidiol (CBD), have been specifically reported to interact with Tykerb. Using cannabis while taking Tykerb can make Tykerb build up in your body. This can raise your risk of side effects from Tykerb.
Before you start treatment with Tykerb, tell your doctor and pharmacist if you use cannabis. By sharing this information with them, you may help prevent possible interactions.
Note: Cannabis is illegal at a federal level but is legal in many states to varying degrees.
Certain medical conditions or other health factors may raise the risk of interactions with Tykerb. Before taking Tykerb, talk with your doctor about your health history. They’ll determine whether Tykerb is right for you.
Health conditions or other factors that might interact with Tykerb include:
Liver problems: Tykerb is broken down by your liver. If you have a liver problem, Tykerb can build up in your body. This can raise your risk of side effects from Tykerb, including liver damage. (Tykerb has a boxed warning about the risk of liver damage. For more information, see the boxed warning at the start of this article.) If you have a liver problem, your doctor may prescribe a dosage of Tykerb that’s lower than usual. And they’ll likely monitor your liver function closely.
Heart problems: Tykerb can sometimes cause side effects on your heart. For example, it can affect your heart rhythm or reduce your heart’s ability to pump blood around your body. If you have a heart problem such as heart failure, a slow heart rate, or an abnormal heart rhythm, talk with your doctor about whether Tykerb is safe for you.
Electrolyte imbalance: Tykerb can affect your heart rhythm. If you have an electrolyte imbalance, such as a low potassium or magnesium level, you may have a higher risk of this side effect. If you have an electrolyte imbalance, your doctor will likely correct this before you start Tykerb. Your doctor will likely monitor your electrolytes during your treatment.
Pregnancy: Tykerb is not safe to take during pregnancy. If you’re pregnant or may become pregnant, talk with your doctor before taking Tykerb. If you’re able to become pregnant, you should use birth control while taking Tykerb and for 1 week after your last dose.
Breastfeeding: You should not breastfeed while taking Tykerb and for 1 week after your last dose. If you’re breastfeeding or planning to breastfeed, talk with your doctor about your options.
Allergic reaction: If you’ve had an allergic reaction to Tykerb or any of its ingredients, your doctor will likely not prescribe Tykerb. This is because taking the drug could cause another allergic reaction. You can ask your doctor about other treatments that may be better for you.
Taking certain steps can help you avoid interactions with Tykerb. Before starting treatment, talk with your doctor and pharmacist. Things to discuss with them include:
- whether you drink alcohol or use cannabis
- the
list of medications you take, as well as any vitamins, supplements, and herbs - what to do if you start taking a new drug during your Tykerb treatment
It’s also important to understand Tykerb’s
If you did not get paperwork with Tykerb, ask your pharmacist to print a copy for you. If you have trouble reading or understanding this information, your doctor or pharmacist can help.
Taking Tykerb exactly as prescribed can also help prevent interactions.
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 another 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.