Controlling nausea and vomiting (anti-emetic therapy)
There are ways to help prevent or reduce nausea (feelings of sickness) and vomiting (being sick), which can sometimes be caused by cancer or its treatment.
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
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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 recieves 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 may occasionally cause nausea.
Some targeted therapies may also occasionally cause nausea.
These are used as painkillers. Some of these drugs can affect the vomiting centre.
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.
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.
Feeling anxious about the cancer or your treatment may cause nausea and vomiting.
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
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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
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Anti-emetic drugs can be given in different ways.
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.
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.
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:
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.
Cyclizine (Valoid®) is an anti-histamine drug that is often used to control sickness.
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.
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.
Possible side effects of anti-emetic drugs
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Anti-emetic drugs can cause side effects. Different drugs will have different side effects and each person may react differently. Some of the more common side effects are listed here, alongside the drugs that may cause them.
If you notice any side effects that are not listed, please discuss them with your doctor, nurse or pharmacist.
Aprepitant, fosaprepitant, granisetron, ondansetron, palonosetron, and tropisetron can all cause constipation. This can usually be relieved by drinking plenty of fluids, eating a high-fibre diet and taking gentle exercise. Sometimes you may need to take laxatives to stimulate your bowel. Your doctor can prescribe these.
Aprepitant, fosaprepitant, granisetron, ondansetron, palonosetron, and tropisetron can all cause headaches. Let your doctor know if you get headaches while having one of these drugs as part of your anti-emetic 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
Cyclizine, chlorpromazine, haloperidol, levomepromazine, palonosetron and lorazepam may cause drowsiness . Let your doctor know if this is a problem.
Indigestion can be caused by dexamethasone. It may help to make sure that you always take the tablets with or after food. Tell your doctor if indigestion is a problem for you as they can prescribe medicines to help.
Dexamethasone may make it difficult for you to get to sleep. This problem can be reduced by ensuring that you take your last dose of the day in the early afternoon, rather than in the evening or before you go to bed.
Metoclopramide may cause muscle twitching which affects 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 effect, stop taking the tablets and tell your doctor, as other medicines may suit you better.
Things you can do for yourself
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Avoid eating or preparing food when you feel sick.
Avoid fried foods, or foods with a strong smell.
Preparing small meals and eating little and often can be helpful.
Eat cold or warm food if the smell of hot food makes you feel sick.
Eat several small snacks and meals each day and chew the food well.
Peppermints or peppermint tea may help some people.
Sip drinks slowly.
Ginger biscuits or ginger beer can help some people.
Don't drink a lot just before you eat.
This can be help you cope with nausea. Using relaxation tapes or taking part in activities that you find relaxing may be useful.
This 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.
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. 63rd edition. 2012. British Medical Association and Royal Pharmaceutical Society of Great Britain.
Hanks, et al. Oxford Textbook of Palliative Medicine. 4th edition. 2009. Oxford University Press.
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.