Emend: An Effective Tool in the Prevention of Nausea and Vomiting

Woman suffering from nausea after chemotherapy

Chemotherapy and some surgeries can trigger the release of a substance called substance P, which binds to NK1 receptors in the brain and can cause nausea and vomiting. By blocking these receptors, Emend helps to prevent or reduce the severity of these side effects.

Emend is available in different forms, including capsules, injections, and oral suspension, and is typically used in combination with other medications that prevent nausea and vomiting.

What Is Emend (Aprepitant)?

Emend, also known by its generic name aprepitant, is a medication used to prevent nausea and vomiting caused by chemotherapy, radiation therapy, and surgery. It belongs to a class of drugs called neurokinin-1 receptor antagonists, which blocks the action of a neurotransmitter called substance P in the brain.

Chemotherapy and radiation therapy often cause nausea and vomiting as side effects, which can be severe enough to affect a patient’s quality of life and ability to continue with treatment. Emend is combined with other anti-nausea medications to prevent these side effects.

This medication is typically taken orally as a capsule or tablet. The dose and duration of treatment may vary depending on the individual patient’s needs and the type of chemotherapy or radiation therapy received. 

Follow the instructions of your healthcare provider and report any side effects or concerns.

What Is Emend Used For?

Emend was approved by the Food and Drug Administration (FDA) to be used with other anti-nausea or antiemetic drugs to prevent acute or delayed chemotherapy-induced nausea.

Certain chemotherapy medicines might cause extreme nausea. This can happen shortly after treatment or a few days later. Some anti-nausea drugs can help reduce nausea once it has occurred, while Emend helps prevent nausea from occurring in the first place.

Adults can also use this medication to avoid nausea and vomiting following surgery.

Emend oral suspension is approved for usage in people 6 months and older, and the capsules are approved for people 12 years and older.

How Does Emend Work?

Substance P is a neurotransmitter that plays a key role in regulating nausea and vomiting. When chemotherapy drugs are given, they can cause the release of substance P, which can stimulate the vomiting center in the brain, leading to nausea and vomiting.

Emend works by blocking the receptors in the brain that substance P normally binds to, thereby preventing its action and reducing the likelihood of nausea and vomiting. 

In addition to blocking substance P, Emend also inhibits other neurotransmitters involved in the vomiting reflex, further reducing the risk of nausea and vomiting.

Emend is available as a pill or injection and is typically given before chemotherapy treatment starts to provide the best protection against chemotherapy-induced nausea and vomiting.

Drug Dosage and Administration

The dosage and administration of Emend may vary depending on several factors, including the patient’s age, weight, medical condition, and the type of chemotherapy or surgery being performed.

However, here are some general guidelines for the dosing and administration of Emend:

For chemotherapy-induced nausea and vomiting: For those 12 years of age and older, the recommended dose is 125 mg taken orally 1 hour before chemotherapy, followed by 80 mg once daily for the next 2 days. Depending on the chemotherapy regimen, you can take it with or without food.  The dosing is weight-based for those less than 12 years old.

For surgery-induced nausea and vomiting: The recommended dose is 40 mg taken orally 3 hours before surgery.

Emend can be taken without regard to food. You should take Emend as prescribed by your healthcare provider. Do not take more or less than the prescribed dose, and do not stop taking the medication without consulting your healthcare provider.

If you miss a dose of Emend, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. 

If you have questions or concerns about the dosing and administration of Emend, talk to your doctors. They can provide more information specific to your situation.

Side Effects

Woman with headache as a side effect of Emend

Like all medications, Emend can cause side effects in some people. Here are some common side effects of Emend:

  • Fatigue
  • Asthenia (fatigue without or before effort)
  • Dizziness
  • Headache
  • Diarrhea
  • Loss of appetite
  • Dehydration
  • Abdominal pain
  • Hiccups
  • Taste changes
  • Decreased white blood cell count

Less common side effects of Emend may include:

  • Allergic reactions such as skin rash, itching, and difficulty breathing
  • Liver problems such as yellowing of the skin and eyes, dark urine, and abdominal pain
  • Low blood pressure
  • Heart palpitations
  • Shortness of breath
  • Dizziness
  • Nausea

You should contact your doctor immediately if you experience any of these symptoms. Sometimes, these side effects can be serious and require immediate medical attention. 

It’s also important to let your doctor know about any other medications or supplements you are taking, as they may interact with Emend and increase the risk of side effects.


Taking precautions when using Emend is essential to ensure it is used safely and effectively. Here are some precautions to keep in mind:

  • Emend is not recommended during pregnancy because there is insufficient data regarding its use. If you are pregnant or planning on becoming pregnant, talk to your doctor before using Emend.
  • Emend can cause dizziness and drowsiness, so it is important to avoid driving or operating heavy machinery until you know how the drug affects you.
  • Emend can cause liver damage, so it is important to have regular liver function tests while taking the medication.
  • If you experience any allergic reactions, such as difficulty breathing, swelling of the face or throat, or a rash, stop taking Emend and seek medical attention immediately.
  • Emend can interact with certain foods and drinks, such as grapefruit juice, so avoiding these foods while taking the medication is important.


The cost of Emend can vary depending on factors such as the dosage, the location, and the pharmacy where it is purchased. That said, you can find a supply of two capsules of Emend 80 mg for about $470.

This information is not a substitute for medical advice or treatment. Talk to your doctor or healthcare provider about your medical condition prior to starting any new treatment. AmeriPharma™ Specialty Care assumes no liability whatsoever for the information provided or for any diagnosis or treatment made as a result, nor is it responsible for the reliability of the content. AmeriPharma™ Specialty Care does not operate all the websites/organizations listed here, nor is it responsible for the availability or reliability of their content. These listings do not imply or constitute an endorsement, sponsorship, or recommendation by AmeriPharma™ Specialty Care. This webpage may contain references to brand-name prescription drugs that are trademarks or registered trademarks of pharmaceutical manufacturers not affiliated with AmeriPharma™ Specialty Care.

Dr. Mark Alfonso, PharmD was born and raised in Pueblo, CO. He received his pharmacy degree from the University of Colorado School of Pharmacy at the Anschutz Medical Campus in 2010. He was board certified in medication therapy management in 2022. The most rewarding part of his job is helping to answer patient questions and concerns. His areas of expertise are community pharmacy and medication therapy management.  In his free time, he enjoys reading and running.