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Emend is available as capsules you can swallow. The capsules come in multiple strengths. It may also be given intravenously.

How It Works

Aprepitant prevents and controls nausea and vomiting by blocking the effects of a chemical in the brain. That chemical is called P/neurokinin 1 (NK1) receptor antagonist.

Why It Is Used

Aprepitant is used to prevent and control nausea and vomiting caused by chemotherapy. It is always used in combination with serotonin antagonists (such as ondansetron) and dexamethasone.

Aprepitant is most often used when the other drugs used to treat nausea and vomiting have not worked well enough.

How Well It Works

Aprepitant, when combined with ondansetron and dexamethasone as part of a 3-day regimen, prevents both acute and delayed nausea and vomiting caused by chemotherapy.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.

Call your doctor if you have:

  • Hives.

Common side effects of this medicine include:

  • Constipation or diarrhea.
  • Hair loss.
  • Headaches.
  • Hiccups.
  • Loss of appetite.
  • Weakness and fatigue.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Aprepitant interacts with many other drugs. Be sure that your doctor knows all the prescription and over-the-counter drugs you are taking.

Blood-thinning drugs, such as warfarin, may not work as well when you take aprepitant. If you are taking a blood thinner, you will need frequent blood tests to make sure that your dose is high enough.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

Aprepitant decreases the effectiveness of birth control pills. If you are taking birth control pills, your doctor will help you choose another method of birth control.

If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.


ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerBrian Leber, MDCM, FRCPC - Hematology
Last RevisedDecember 14, 2012

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