Keytruda (pembrolizumab) is a prescription drug used to treat certain types of cancer in adults and some children. Keytruda is not known to interact with alcohol, other medications, or supplements.

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.

Keytruda hasn’t been reported to interact with other drugs. However, that doesn’t mean interactions can’t happen. For example, other drugs could be developed in the future that may interact with Keytruda.

Because of this, before you start treatment with Keytruda, 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 Keytruda interacts with herbs or vitamins and supplements, see the “Are there other interactions with Keytruda?” section below.)

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

Keytruda is not known to interact with alcohol. If you have questions about consuming alcohol during Keytruda treatment, talk with your doctor or pharmacist.

Keytruda may have other interactions. They could occur with supplements, foods, vaccines, or even lab tests. See below for details. Note that the information below does not include all other possible interactions with Keytruda.

Does Keytruda interact with supplements?

Before starting Keytruda treatment, talk with your doctor and pharmacist about any herbs or vitamins and 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.

Keytruda and herbs

There are currently no reports of Keytruda interacting with herbs. But this doesn’t mean that interactions with herbs won’t be recognized in the future.

For this reason, it’s still important to check with your doctor or pharmacist before taking any of these products while using Keytruda.

Keytruda and vitamins

There are currently no reports of Keytruda interacting with vitamins. But this doesn’t mean that vitamin interactions won’t be recognized in the future.

For this reason, it’s still important to check with your doctor or pharmacist before taking any of these products while receiving Keytruda.

Does Keytruda interact with food?

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

Does Keytruda interact with vaccines or lab tests?

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

Does Keytruda interact with cannabis or CBD?

There are currently no reports of Keytruda 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 Keytruda.

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

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

Stem cell transplant: Receiving Keytruda before or after an allogeneic stem cell transplant can cause serious or life threatening complications. (With an allogeneic stem cell transplant, you receive donor stem cells from another person.) If you’ve had or plan to have this type of transplant, talk with your doctor about whether Keytruda is right for you.

Multiple myeloma: If you have multiple myeloma (bone marrow cancer) and you’re receiving treatment with dexamethasone and a thalidomide-type drug, your doctor likely won’t prescribe Keytruda for you. Receiving Keytruda with these drugs can raise your risk of death.

Pregnancy: Keytruda is not safe to receive during pregnancy. The drug can cause fetal harm. If you’re pregnant or planning a pregnancy, talk with your doctor about your treatment options. If you’re able to become pregnant, you should use birth control during Keytruda treatment and for 4 months after your last dose.

Breastfeeding: It’s not known whether it’s safe to receive Keytruda while breastfeeding. But due to the possible risk of serious side effects in a child who’s breastfed, you should not breastfeed during Keytruda treatment or for 4 months 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 Keytruda or any of its ingredients, your doctor will likely not prescribe Keytruda. 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 Keytruda. 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 (they can also help you fill out a medication list)
  • what to do if you start taking a new drug during your Keytruda treatment

It’s also important to understand Keytruda’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 Keytruda, ask your pharmacist to print a copy for you.)

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

Receiving Keytruda 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.