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What is aprepitant?

Aprepitant (also called Emend®) is used to prevent upset stomach and vomiting (throwing up) caused by chemotherapy and surgery. Aprepitant is available in 80mg and 125mg capsules and an oral liquid made by the pharmacy. Aprepitant is taken by mouth one (1) hour before chemotherapy or the morning of chemo. Then, it is given one (1) time a day for 3 days. Fosaprepitant is a liquid form of this same drug that is given by vein (IV). It is injected over at least 30 minutes before chemo is started.

Possible side effects of aprepitant

Most common

  • Heartburn
  • Urinary tract infection
  • Feeling tired or weak
  • Loose stools (diarrhea)
  • Not hungry
  • Belly pain
  • Hiccups
  • Feeling dizzy
  • Headache

If you have any of these side effects, tell the doctor right away:        

With aprepitant or fosaprepitant products

  • Allergic reaction: Itching or hives; swelling in your face or hands; swelling or tingling in your mouth or throat; chest tightness; trouble breathing
  • Blistering or peeling skin, red skin rash
  • Fever, chills, cough, sore throat, body aches
  • Feeling lightheaded, dizzy or faint

With fosaprepitant only

  • Irritated or swollen skin where the medicine is given by IV
  • Pain where the medicine was given by IV

These are the most common side effects, but there may be others. Please report all side effects to the doctor or nurse. In case of a severe side effect or reaction, call the doctor, nurse, or pharmacist at 901-595-3300. If you are outside the Memphis area, dial toll-free 1-866-2STJUDE (1-866-278-5833), and press 0 once the call is connected.

How to take aprepitant

Oral capsule

  • Swallow capsule whole. Do not open, crush, or chew the capsule.

Oral suspension

  • The oral liquid comes in a prefilled oral syringe that contains your prescribed dose.
  • Remove cap from oral syringe. Slowly give the liquid by mouth along the inner cheek.
  • Throw away the oral syringe and its cap after each use.

IV liquid

  • A nurse or other staff member will give you this medicine.

Special instructions for aprepitant

  • Tell your doctor if:
    • you are pregnant or breastfeeding
    • you have liver disease
  • While taking this drug, birth control pills and other hormone-based birth control might not work as well to prevent pregnancy. Use some other kind of birth control, like a condom, while taking this medicine and for one (1) month after therapy ends.
  • Some medicines can affect how aprepitant or fosaprepitant works. Tell your doctor if you are taking any of the following:
    • Cisapride or pimozide
    • Clarithromycin, itraconazole, ketoconazole, nefazodone, nelfinavir, ritonavir, or troleandomycin
    • Carbamazepine, diltiazem, phenytoin, or rifampin
  • If you are taking warfarin, talk with your doctor. You may need to have your blood work checked more closely while you are taking aprepitant or fosaprepitant.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).