Managing nausea and vomiting (anti-sickness therapy)

Some cancers and cancer treatments can cause nausea and vomiting. Feeling anxious can also make you feel or be sick.

There is an area in the brain called the vomiting centre and this controls nausea and vomiting. Different things can stimulate the vomiting centre and cause you to feel sick.

There are different types of drugs that can help treat nausea and vomiting. These are called anti-sickness (anti-emetic) drugs. These drugs can be given as:

  • tablets
  • injections
  • suppositories
  • skin patches.

If you are having a cancer treatment which is known to cause nausea and vomiting, you may start taking anti-sickness drugs before your treatment begins.

Anti-sickness drugs can cause side effects which vary depending on which drugs you are taking. Side effects may include:

  • constipation
  • headaches
  • tiredness.

Other things that can help you to manage nausea and vomiting include eating small, frequent meals and avoiding foods with a strong smell or taste.

Causes of nausea and vomiting

An area of the brain called the vomiting centre controls nausea and vomiting. Nausea or vomiting happens when the vomiting centre is stimulated. It may be stimulated by:

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

There are several reasons why someone with cancer may have nausea and vomiting. These include cancer treatments, physical changes in the body and emotional reasons. Some of the reasons why someone with cancer may experience nausea and vomiting are listed below.

Treatments that can cause nausea and vomiting

Cancer treatments that may cause nausea and vomiting include:

  • chemotherapy
  • radiotherapy, if given to the brain, stomach, bowel or close to the liver
  • hormonal therapies
  • targeted therapies
  • morphine-based medicines, which are used as painkillers.

Physical causes of nausea and vomiting

Sometimes, nausea and vomiting can be caused by the following reasons:

  • Changes in the body chemistry. High levels of calcium in the blood can cause nausea and vomiting.
  • Pressure in the brain. If the pressure in the brain is raised, it can affect the vomiting centre and cause you to be sick.
  • Damage to the liver. If the liver is not working properly, waste products can build up in the blood, leading to nausea and vomiting.
  • Constipation. This can sometimes cause nausea and vomiting.
  • Bowel obstruction. Some cancers, especially cancers that affect the pelvis or abdomen, can cause the bowel to become blocked (bowel obstruction), making you vomit.

Emotional causes of nausea and vomiting

In other cases, there are emotional reasons for nausea and vomiting, such as the following:

  • Anxiety. Feeling anxious about the cancer or your treatment may cause nausea and vomiting.
  • Feelings of nausea and vomiting before treatment (anticipatory nausea). Sometimes, feelings of nausea and vomiting can be triggered by a situation that reminds you of when you were feeling or being sick in the past. This is called anticipatory nausea. It can occur with chemotherapy and other cancer treatments.

Anti-sickness (anti-emetic) drugs

There are many different types of drugs that help treat nausea and vomiting. These are called anti-sickness (anti-emetic) drugs. They can be given as:

  • tablets
  • injections
  • suppositories
  • skin patches.

If you are having a cancer treatment which is known to cause nausea and vomiting, you may start taking anti-sickness drugs before your treatment begins.

How anti-sickness drugs work

The type of anti-sickness treatment you have will depend on the cause of your sickness. The most effective way of managing nausea and vomiting is by treating the cause. 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 the most effective treatment.

There are many types of drugs that can be 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. This helps to move food through the intestines more quickly.

If the first anti-sickness drug you try does not work, your doctor may recommend trying a different one.

How anti-sickness drugs are given

Anti-sickness drugs can be given in different ways. If you are unable to swallow a tablet, there are other ways you can have the drug:

By mouth

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

Into a vein

Some anti-sickness drugs can be diluted in fluid and given as an injection straight into the vein or by a drip into the vein (intravenous infusion). The drugs can 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 bend above your elbow (PICC line).

Into the muscle

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

Under the skin (subcutaneously)

You may have the drugs as an injection into the fatty tissue under the skin, using a small needle and syringe. They can also be given over several hours through 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-sickness 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.

When anti-sickness drugs are given

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-sickness drugs before the treatment starts. It may also be given for a few days after the treatment has finished.

If you feel sick or are being sick because of the cancer itself, it may take a while to relieve this symptom. You will be given anti-sickness drugs and, if possible, the cause of the sickness will be treated.

It is often easier to control and prevent nausea if you take anti-sickness drugs regularly, rather than treating the nausea after it has started. If you have any new nausea or vomiting, or your nausea and vomiting becomes worse or lasts for more than a few days, let your doctor or nurse know.

Common types of anti-sickness drugs

You may be given a combination of different drugs to control nausea and vomiting. Some of the drugs used are listed below:

5HT3 inhibitors

These drugs are used to treat sickness caused by chemotherapy and radiotherapy. They work best when given with steroids.

5HT3 inhibitors work by blocking a chemical called serotonin (5HT). Serotonin affects the receptors in the gut and brain called 5HT3 receptors, causing you to feel sick.

5HT3 inhibitors include:

  • granisetron (Kytril®)
  • ondansetron (Zofran®)
  • tropisetron (Navoban®).

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


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

Metoclopramide (Maxolon®) and domperidone (Motilium®)

These commonly used drugs work by helping to empty the stomach to relieve feelings of sickness.

Prochlorperazine (Stemetil®) and chlorporamazine

These drugs work by acting on the vomiting centre in the brain to help control sickness. Prochlorperazine (Stemetil®) can be given as a tablet that dissolves in the mouth (Buccastem®). Chlorporamazine is sometimes used in advanced cancer, when other anti-sickness drugs have not worked.

Anti-histamine drugs

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

Sedative drugs

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

Anti-anxiety drug

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

Neurokin 1 (NK1) inhibitor

NK1 inhibitors are drugs that work by blocking a chemical that affects neurokinin receptors in the body that 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. Examples of NK1 inhibitors include:

  • aprepitant (Emend®), which is given as a tablet
  • fosaprepitant (Ivemend®), which is given as an injection into a vein.

Possible side effects of anti-sickness drugs

Sometimes, anti-sickness drugs can cause side effects. Different drugs will have different side effects and each person may react differently.

We have listed some of the more common side effects here. We also tell you which drugs may cause these side effects. If you notice any side effects that are not listed below, tell your doctor, nurse or pharmacist.


The drugs that can cause constipation are:

  • aprepitant
  • fosaprepitant
  • granisetron
  • ondansetron
  • palonosetron
  • tropisetron.

Constipation can usually be relieved by drinking plenty of fluids, eating a high-fibre diet, and doing some gentle exercise.

Sometimes, you may need to take laxatives to stimulate your bowels. Your doctor can prescribe these for you.


The drugs that can cause headaches are:

  • aprepitant
  • fosaprepitant
  • granisetron
  • ondansetron
  • palonosetron
  • tropisetron.

Let your doctor know if you get headaches while having any of these drugs as part of your anti-sickness therapy.

Flushing of the skin

When injected, ondansetron, tropisetron, and dexamethasone can cause flushing or a sensation of warmth. Although this is rare, tell your doctor if you have these side effects.

Tiredness (fatigue) and feelings of weakness

The drugs that can cause drowsiness are:

  • cyclizine
  • chlorpromazine
  • haloperidol
  • levomepromazine
  • palonosetron
  • lorazepam.

Tell your doctor if this is a problem.


Indigestion can be caused by dexamethasone. It may help to take these tablets with or after food. Tell your doctor if indigestion is a problem for you, as they can prescribe medicines to help.

Difficulty sleeping (insomnia)

Dexamethasone may make it difficult for you to get to sleep. This problem can be reduced by taking your last dose of the day early in the afternoon, rather than in the evening before you go to bed.


Metoclopramide may cause muscle twitching. This can affect different parts of the body, including the face, neck and shoulders. This is more commonly seen in children and young adults. If you notice this side effect, stop taking the tablets and tell your doctor, as other medicines may be better for you.

Managing nausea and vomiting

Eating problems caused by sickness

If feeling sick is putting you off your food, the following tips may help:

  • Avoid eating or preparing food when you feel sick.
  • Avoid fried foods or foods with a strong smell.
  • Prepare small meals and eat little and often.
  • Eat cold or warm food if the smell of hot food makes you feel sick.
  • Eat little and often and chew your food well.
  • Try eating peppermints or drinking peppermint tea.
  • Sip drinks slowly.
  • Try eating ginger biscuits or drinking ginger beer.
  • Try not to drink a lot just before you eat.


Using relaxation tapes or taking part in activities that you find relaxing may help you cope with nausea.


There is some evidence that acupuncture may help to control nausea, but more research is needed.

Acupuncture involves placing thin, sterile needles into the skin to affect energy points. It is part of traditional Chinese medicine. Sea-bands® (acubands) use the principle of acupressure, which is similar to acupuncture. They apply pressure to specific points on the body, usually the wrist, to control nausea. Some people find acubands helpful in reducing nausea. They are available from chemists and health food shops.

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