An anti-sickness medicine for chemotherapy

Aprepitant

An anti-sickness medicine used with others to prevent nausea and vomiting from chemotherapy.

What is Aprepitant?

Aprepitant is an anti-sickness (antiemetic) medicine used to help prevent the nausea and vomiting that some chemotherapy treatments cause. It is given together with other anti-sickness medicines rather than on its own, and it is especially good at preventing sickness in the days after chemotherapy. It blocks a chemical signal in the brain involved in vomiting. It interacts with many other medicines and can make hormonal contraception less reliable, so extra precautions are needed.

Education and reference only. This is a plain-language guide to Aprepitant — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.

Written by Meds Global Health Clinical Team · Clinically reviewed by Dr Muhammad Suffyan, MB BS, Founder & Clinical Director · Last reviewed · How we review
Class: Anti-sickness medicines (antiemetics) → Brands: Emend
Aprepitant (Anti-sickness medicines (antiemetics)) — Meds Global Health reference card with 2D molecular structure
Aprepitant — Anti-sickness medicines (antiemetics). The image shows the active ingredient's 2D molecular structure.

What it is

Aprepitant is an antiemetic used to prevent nausea and vomiting caused by chemotherapy, particularly the more strongly sickness-inducing treatments. It is used as part of a combination of anti-sickness medicines rather than alone, and is taken around the time of chemotherapy. It is taken by mouth, usually starting on the day of treatment and continuing for a couple of days afterwards.

How it works

Aprepitant blocks a receptor in the brain (the NK1 receptor) that responds to a signal called substance P, which is involved in triggering vomiting. By blocking this pathway it helps prevent both the early and the delayed sickness that chemotherapy can cause. Working alongside other anti-sickness medicines that act in different ways gives more complete protection.

Company & origin

Originated / developed by: Merck (originator).

An antiemetic used in the UK to prevent nausea and vomiting caused by chemotherapy.

Practical use

How to take Aprepitant

General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.

  • Take it on the schedule your team gives you around chemotherapy, usually starting on the treatment day and continuing for a couple of days after.
  • Keep taking it as planned even if you do not feel sick, as it is mainly there to prevent nausea rather than treat it once started.
  • Use it together with the other anti-sickness medicines your team prescribes, not instead of them.
  • If you use hormonal contraception, use additional non-hormonal precautions during treatment and for a while afterwards, as advised.
  • If you miss a dose, contact your team for advice rather than guessing, as timing around chemotherapy matters.

Weighing it up

Advantages & disadvantages of Aprepitant

Advantages

  • Adds extra protection against chemotherapy nausea when used with other anti-sickness medicines.
  • Particularly good at preventing delayed sickness in the days after treatment.
  • Taken as a short oral course, which is convenient around chemotherapy.

Disadvantages

  • Interacts with many other medicines because of how it affects drug processing.
  • Can make hormonal contraception less reliable, needing extra precautions.
  • Used only alongside other anti-sickness medicines, not as a standalone treatment.

Practical use

Good to know

Aprepitant is given with other anti-sickness medicines, such as a 5HT3 blocker and a steroid, because the combination works better than any one alone for chemotherapy sickness. It is particularly valued for preventing delayed nausea in the days after treatment, so it is usually taken on a set schedule around chemotherapy even if you do not yet feel sick. Importantly, it interacts with many medicines because it affects how the body processes them, and it can make hormonal contraception (such as the pill, patch or implant) less reliable — so additional non-hormonal precautions are advised during and for a while after treatment. Always give your team a full list of your medicines, including anything bought over the counter.

Who should not take it / use with caution

  • Anyone who has had an allergic reaction to aprepitant should avoid it.
  • It is used with caution in significant liver disease and should be reviewed there.
  • People taking certain medicines that strongly interact with it may need alternatives.

Monitoring

  • Your team checks how well nausea and vomiting are controlled across the chemotherapy cycle.
  • Medicines are reviewed for interactions before and during treatment.
  • Contraception advice is given because effectiveness can be reduced.

Side effects

  • Tiredness, hiccups, headache and constipation or diarrhoea can occur.
  • Loss of appetite and indigestion are sometimes reported.
  • Less commonly, dizziness or, rarely, an allergic reaction — report severe or unusual symptoms.

Key interactions

  • It affects the CYP3A4 enzyme system, so it interacts with many medicines — give your team a full list.
  • It can reduce the effectiveness of hormonal contraception, so use extra non-hormonal precautions.
  • Doses of some medicines, such as certain steroids and blood thinners, may need adjusting.

Available as: Capsules taken by mouth (a related injectable form is also available).

Answers

Aprepitant: frequently asked questions

Is aprepitant used on its own?

No, it is used together with other anti-sickness medicines, because the combination prevents chemotherapy nausea better than any single medicine.

Why take it before I feel sick?

It mainly prevents nausea rather than treating it once it starts, so it is taken on a set schedule around chemotherapy, including the days afterwards.

Does it affect my contraception?

It can make hormonal contraception less reliable, so additional non-hormonal precautions are advised during and for a while after treatment.

Why does my team need my full medicine list?

Aprepitant interacts with many medicines through the body's drug-processing system, so doses may need adjusting and some combinations avoided.

What is it especially good at?

It is particularly effective at preventing delayed nausea and vomiting in the days following chemotherapy.

The wider class

About Anti-sickness medicines (antiemetics)

Aprepitant belongs to the anti-sickness medicines (antiemetics) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.

AntiemeticsDrugs that prevent and treat nausea and vomiting — the right choice depends on the cause. OndansetronA powerful anti-sickness medicine for nausea from chemotherapy, surgery or severe pregnanc…MetoclopramideA short-term anti-sickness medicine that also speeds stomach emptying; used only briefly b…ProchlorperazineAn antisickness and anti-vertigo medicine used short term for nausea, vomiting and dizzine…CyclizineAn antihistamine anti-sickness medicine used to prevent and treat nausea, vomiting and ver…CinnarizineAn antihistamine-type medicine used for travel sickness and for inner-ear balance problems…GranisetronA powerful anti-sickness medicine used to prevent nausea and vomiting from chemotherapy, r…BetahistineA histamine-like medicine used to reduce the dizziness, vertigo, ringing in the ears and h…NabiloneA man-made cannabis-related medicine for chemotherapy sickness when standard anti-sickness…FosaprepitantAn injection given with chemotherapy to help prevent sickness, especially the delayed kind…RolapitantA long-acting tablet taken with chemotherapy to help prevent delayed nausea and vomiting.…AlizaprideA dopamine-blocking antiemetic used to prevent and treat nausea and vomiting, such as with…DolasetronAn anti-sickness medicine used to prevent and treat nausea and vomiting, working by blocki…LevosulpirideA dopamine-blocking medicine used as an anti-sickness treatment and to ease the symptoms o…MetopimazineA dopamine-blocking anti-sickness medicine used to prevent and ease nausea and vomiting.…NetupitantAn anti-sickness medicine that helps prevent chemotherapy nausea and vomiting, usually com…PalonosetronA long-acting anti-sickness medicine that helps prevent nausea and vomiting from chemother…TropisetronA 5HT3-blocking antiemetic used to prevent nausea and vomiting from chemotherapy, with con…TrimethobenzamideAn anti-sickness medicine used to relieve nausea and vomiting, used mainly outside the UK.…BromoprideAn anti-sickness medicine that blocks dopamine to relieve nausea and vomiting and help the…CleboprideAn older medicine that blocks dopamine to relieve nausea and help the stomach empty.…DomperidoneA medicine for nausea and vomiting that also helps the stomach empty — used short-term and…

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Authoritative sources

  • BNF
  • NICE CKS

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