Nausea and vomiting

Nausea (feeling sick) and vomiting (being sick) can sometimes be caused by cancer or its treatments.

Chemotherapy, radiotherapy, and hormonal and targeted therapies can all cause nausea and vomiting. Physical changes can cause these side effects too. This might be because of damage to the liver or pressure on the brain. And if you’re feeling anxious about cancer and your treatment, this can also make you feel or be sick.

There are many different types of drugs that help treat nausea and vomiting. These are called anti-emetics. They can be given as a tablet, an injection, a suppository or a skin patch. If you’re having a cancer treatment which is known to cause nausea and vomiting, you may start taking anti-emetics before your treatment begins.

Anti-emetics can cause a number of side effects but vary depending on which drugs you are taking. Side effects may include constipation, headaches and tiredness.

There are some things you can do to help control nausea and vomiting. These include eating small, frequent meals and avoiding foods with a strong smell or taste.

Coping with nausea and vomiting

This information covers the medicines that are commonly used, which are known as anti-sickness drugs (or anti-emetics), as well as other ideas to help you cope.

If you are having chemotherapy or radiotherapy treatment, this information should ideally be read with our general information about these treatments.

Causes of nausea and vomiting

Within the body, nausea and vomiting are controlled by an area of the brain known as the vomiting centre. This area may be stimulated to cause nausea or vomiting if it receives signals from:

  • nerves within the gut (stomach)
  • another part of the brain called the chemoreceptor trigger zone (CTZ)
  • the inner ear – caused by body motion
  • our senses – taste, smell and pain, for example
  • our emotions – if we’re scared or nervous, for example.

Some of the reasons why someone with cancer may experience nausea and vomiting are listed here:



Some types of chemotherapy can affect the vomiting centre and cause nausea and vomiting.


If radiotherapy is given to the brain, stomach, bowel, or close to the liver, it may lead to nausea and vomiting.

Hormonal therapies

Hormonal therapies may occasionally cause nausea.

Targeted therapies

Some targeted therapies may also occasionally cause nausea.

Morphine-based medicines

These are used as painkillers. Some of these drugs can affect the vomiting centre.

Physical reasons

Changes in the body chemistry

High levels of calcium in the blood can cause nausea and vomiting.

Pressure within the brain

If the pressure within the brain is raised it can affect the vomiting centre and cause vomiting.

Damage to the liver

If the liver isn't working properly, waste products can build up in the blood, leading to nausea and vomiting.


This can sometimes cause nausea and vomiting.

Bowel obstruction

If the bowel becomes blocked (obstructed) it can cause vomiting. Bowel obstruction can be caused by some types of cancer, especially cancers that affect the pelvis or abdomen.

Emotional reasons


Feeling anxious about the cancer or your treatment may cause nausea and vomiting.

Anticipatory nausea

Feelings of nausea, and sometimes vomiting, can occasionally be triggered by circumstances that remind you of previous episodes of nausea and vomiting. This can sometimes occur with chemotherapy and other cancer treatments.

How anti-emetic drugs work

The type of anti-sickness treatment you receive will depend on the cause of your sickness. Sometimes there is more than one cause of nausea and vomiting and more than one type of treatment may be needed. A combination of drugs may be used as the most effective treatment.

Many different types of drugs are used to control nausea and vomiting. Some of these work on the brain by preventing the stimulation of the vomiting centre.

Others work on the gut by speeding up the rate at which the stomach empties, and so helping to move food through the intestines more quickly.

The most effective way of controlling nausea and vomiting is by treating the cause, if possible.

How anti-emetic drugs are given

Anti-emetic drugs can be given in different ways.

By mouth

Some tablets can be swallowed with plenty of water, while others can be placed under the tongue (sublingually) to dissolve.

Into a vein

Some anti-emetics can be diluted in a fluid and given as an injection into the vein or by a drip into the vein (intravenous infusion). The drugs will be given through either a small tube (cannula) in your hand or arm, or a larger tube into a vein in the chest (central line) or the crook of your arm (PICC line).

Into the muscle

The drugs are given by injection into a muscle (intramuscular injection).

Under the skin (subcutaneously)

The drugs can either be injected into the fatty tissue under the skin, using a small needle and syringe, or given slowly over several hours, using a pump attached to a small needle that is placed just under the skin.


These are put into the back passage (rectum), where they dissolve and are absorbed into the bloodstream through the lining of the gut.

Skin patches

Some anti-emetic drugs can be absorbed through the skin (transdermally) from a small patch that is stuck onto the skin like a plaster. The patch is usually changed every couple of days.

Some cancer treatments, including certain chemotherapy drugs, are known to cause nausea and vomiting. If you are taking these drugs, you will be given anti-emetic therapy before the treatment starts. It may also be continued for a few days after the treatment has finished.

When someone feels sick or nauseated because of the cancer itself, it can take a while to control this distressing symptom. You will be given anti-emetics and, if possible, the cause of the sickness will be treated.

It's often easier to control nausea and prevent vomiting if you take the anti-emetics regularly, rather than once the nausea has built up. If you have any nausea or vomiting that is new, becomes worse or lasts for more than a few days, let your doctor or nurse know.

Common anti-emetics

It's not unusual to be given a combination of different drugs to control nausea and vomiting. Some of the types of drugs used are:

5HT3 inhibitors

These drugs are used to control sickness caused by chemotherapy and radiotherapy. They work best when given with steroids. They work by blocking a chemical called serotonin (5HT), which acts on receptors in the gut and brain called 5HT3 receptors. 5HT3 blockers include granisetron (Kytril®), ondansetron (Zofran®) and tropisetron (Navoban®).

Palonosetron (Aloxi®) is a new 5HT3 blocker that acts over a longer time and is given by weekly injection.


These are often given along with other anti-emetic drugs to treat sickness caused by chemotherapy. They can also be used to control sickness when someone has advanced cancer. Dexamethasone is the most commonly used steroid.

Drugs that help empty the stomach to relieve feelings of sickness

Metoclopramide (Maxolon®) and domperidone (Motilium®) both work in this way and are commonly used.

Drugs that act on the vomiting centre in the brain

Prochlorperazine (Stemetil®) is often used to control sickness. One of the ways in which it can be given is as a tablet that dissolves in the mouth (Buccastem®). Chlorporamazine is another drug that acts in the same way. It's occasionally used in advanced cancer when other anti-emetic drugs haven't worked. 

Anti-histamine drugs

Cyclizine (Valoid®) is an anti-histamine drug that is often used to control sickness.

Sedative drugs

Haloperidol (Serenace®) is a sedative drug that can be used in low doses to help control sickness caused by drugs like morphine. Levomepromazine (Nozinan®) is another sedative drug that may be used in advanced cancer when other anti-sickness drugs haven't worked. They can be taken as tablets or given through a small pump called a syringe driver, which is used when someone is having difficulty swallowing.

Anti-anxiety drug

Lorazepam (Ativan®)This is an anti-anxiety drug that is usually used along with another anti-emetic to control sickness caused by chemotherapy.

Neurokin 1 (NK1) inhibitor

NK1 inhibitors are newer drugs that work by blocking a chemical that acts on neurokinin receptors in the body to cause nausea. They are usually given along with steroids and a 5HT3 inhibitor to control sickness caused by chemotherapy, particularly with a drug called cisplatin. Aprepitant (Emend®) is a tablet and a fosaprepitant (Ivemend®) is given as an injection into a vein.

References and thanks

This section has been compiled using information from a number of reliable sources including:

  • Sweetman, et al. Martindale: The Complete Drug Reference. 37th edition. 2011. Pharmaceutical Press.
  • British National Formulary. 67th edition. 2014. British Medical Association and Royal Pharmaceutical Society of Great Britain.
  • Hanks, et al. Oxford Textbook of Palliative Medicine. 4th edition. 2009. Oxford University Press.

If you’d like further information on the sources we use, please feel free to contact us.


Thank you to Ms Jackie Chipps, Clinical Nurse Specialist in Community Palliative Care, and all of the people affected by cancer who reviewed this edition. Reviewing information is just one of the ways you could help when you join our Cancer Voices Network.

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