Enhertu (fam-trastuzumab deruxtecan-nxki) is a prescription drug used to treat certain types of cancer. This drug isn’t known to interact with other medications, alcohol, or supplements. But Enhertu should not be used in certain situations, such as during pregnancy.

Enhertu is used in adults to treat the following types of cancer in certain situations:

Enhertu contains the active ingredient fam-trastuzumab deruxtecan-nxki.† (An active ingredient is what makes a drug work.) The drug comes as a powder that’s mixed into a liquid solution by a healthcare professional. You’ll receive Enhertu as an intravenous (IV) infusion (an injection into a vein given over a period of time).

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 Enhertu’s possible interactions. And for more information about Enhertu, including details about its uses, see this article.

* HER2 stands for “human epidermal growth factor receptor 2.” A high level of the HER2 protein helps cancer cells grow and spread.
† The reason “-nxki” appears at the end of the drug’s name is to show that the drug is distinct from similar medications that may be created in the future.

Certain health conditions or other factors could raise your risk of harm if you receive Enhertu. In such cases, your doctor may not prescribe the drug for you. These are known as contraindications. Enhertu’s contraindications are described below.

If you’ve had a severe infusion reaction. If you’ve had a severe infusion reaction to Enhertu or any of its ingredients, your doctor likely won’t prescribe Enhertu. This is because receiving the drug could cause another reaction. You can ask your doctor about other treatments that may be better options for you.

If you’re pregnant. It’s not safe to receive Enhertu infusions during pregnancy. In fact, the drug has a boxed warning for the risk of fetal harm. To learn more, see the “Boxed warnings” section above.

Enhertu is not known to interact with alcohol. However, Enhertu and alcohol can cause some similar side effects, such as nausea and headache. You may be more likely to experience these side effects if you drink alcohol during your Enhertu treatment.

If you have questions about consuming alcohol with Enhertu, talk with your doctor or pharmacist.

There are no drugs known to interact with Enhertu. However, new interactions could be recognized in the future.

For this reason, before you start Enhertu treatment, 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 with Enhertu that may be discovered later. (To learn whether Enhertu interacts with supplements, herbs, and vitamins, see the “Are there other interactions with Enhertu?” section below.)

If you have questions about drug interactions that may affect you, talk with your doctor or pharmacist.

Enhertu is not known to interact with supplements, foods, vaccines, or lab tests. See below for details.

Does Enhertu interact with supplements?

Before you start Enhertu treatment, talk with your doctor and pharmacist about any supplements, herbs, and vitamins 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.

Does Enhertu interact with food?

There are currently no reports of Enhertu interacting with food. If you have questions about eating certain foods during your treatment with Enhertu, talk with your doctor.

Does Enhertu interact with vaccines or lab tests?

There are currently no reports of Enhertu interacting with vaccines or lab tests. If you have questions about receiving specific vaccines or having lab tests done during your Enhertu treatment, talk with your doctor.

Does Enhertu interact with cannabis or CBD?

There are currently no reports of Enhertu interacting with cannabis (commonly called marijuana) or cannabis products such as cannabidiol (CBD). But as with any drug or supplement, talk with your doctor before using cannabis with Enhertu.

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 Enhertu. Before starting Enhertu treatment, talk with your doctor about your health history. They’ll determine whether Enhertu is right for you.

Health conditions or other factors that might interact with Enhertu include:

Heart condition. In rare cases, Enhertu may weaken the left side of the heart. This makes it harder for your heart to pump blood. Having an existing heart condition, such as heart failure, may raise your risk of this side effect. Or it could worsen your current heart condition.

Your doctor may monitor your heart health closely during treatment if they prescribe Enhertu for you. Or in some cases, they may recommend other treatment options that may be safer for you.

Lung condition. Enhertu has a boxed warning about the risk of serious lung conditions. If you already have a lung or breathing problem, talk with your doctor about whether Enhertu is right for you. To learn more, see the “Boxed warnings” section above.

Pregnancy. Enhertu is not safe to receive while pregnant. In fact, the drug has a boxed warning about the risks of fetal harm if received during pregnancy. To learn more, see the “Boxed warnings” section above.

Breastfeeding. It’s not known whether Enhertu passes into breast milk or causes side effects in a child who is breastfed. But due to the risk of serious side effects, it’s recommended that you do not breastfeed during your Enhertu treatment or for at least 7 months after your last dose.

Allergic reaction. If you’ve had an allergic reaction to Enhertu or any of its ingredients, your doctor will likely not prescribe Enhertu. This is because receiving the drug could cause another allergic reaction. You can ask your doctor about other treatments that may be better choices for you.

Taking certain steps can help you avoid interactions with Enhertu. Before starting treatment, talk with your doctor and pharmacist. Things to discuss with them include:

  • Whether you drink alcohol or use cannabis.
  • Other medications you take, as well as any vitamins, supplements, and herbs. Your doctor or pharmacist can help you fill out a medication list.
  • What to do if you start taking a new drug during your Enhertu treatment.

It’s also important to understand Enhertu’s label and other paperwork that may come with the drug. Colored stickers that describe interactions may be on the label. And the paperwork (sometimes called the patient package insert or medication guide) may have other details about interactions. (If you did not get paperwork with Enhertu, ask your pharmacist to print a copy for you.)

If you have trouble reading or understanding this information, your doctor or pharmacist can help.

If you still have questions about Enhertu and its possible interactions, talk with your doctor.

Questions you may want to ask your doctor include:

  • If I receive Enhertu and have certain health conditions, will I be monitored more closely during treatment?
  • How do Enhertu’s interactions compare with those of other drugs that can treat my condition?
  • Should I let you know if I make lifestyle changes during my Enhertu treatment, such as to my diet or exercise routine?
  • Could I still receive Enhertu even if it interacts with a health condition I have?

To learn more about Enhertu, see these articles:

To get information on different conditions and tips for improving your health, subscribe to any of Healthline’s newsletters. You may also want to check out the online communities at Bezzy. It’s a place where people with certain conditions can find support and connect with others.

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.