Controlling nausea and vomiting (anti-emetic therapy)

Causes Back to top

The mechanisms by which a person feels sick or vomits are complicated. 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 by nerves within the gut (stomach) or by other parts of the brain. Psychological and emotional factors can also influence whether a person feels sick.

Some of the reasons why someone with cancer may experience nausea and vomiting are listed below.

Treatments

• Chemotherapy Some types of chemotherapy can affect the part of the brain known as the vomiting centre and cause nausea and vomiting.
• Radiotherapy 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.
• 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, or raised pressure within the brain, can affect the vomiting centre.
• Damage to the liver If the liver is not working properly, waste products can build up in the blood, leading to nausea and vomiting.
• Blockage of the bowel This can be caused by some types of cancer, especially cancers that affect the pelvis or abdomen.

Emotional reasons

• Anxiety 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.

How anti-emetic medicines work Back to top

The type of anti-sickness treatment you receive will depend on the cause. Sometimes there is more than one cause of nausea and vomiting and more than one type of treatment may be needed. The drugs also work in different ways and are often used together to best effect.

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 help 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 the drugs are given Back to top

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 by drip Some anti-emetics can be diluted in a fluid and given through a small tube (cannula) inserted into the vein (intravenously).

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

• Into the fatty tissue under the skin (subcutaneously) The drugs are either injected using a syringe or given slowly over several hours, using a pump attached to a small needle that is placed just under the skin.

• Suppositories 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 changed every three days. 

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

When someone feels sick or nauseated due to 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.

Whatever the cause of the sickness, the anti-emetics should be taken regularly so that the sickness does not have a chance to come back. If you have any nausea or vomiting which is new, becomes worse, or lasts more than a few days, let your doctor or nurse know.

Common anti-emetics Back to top

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 are often given along with steroids. They work by blocking a chemical called serotonin (5HT) which acts on receptors called 5HT3 and causes sickness. They include granisetron (Kytril®), ondansetron (Zofran®), and tropisetron (Navotan®).

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

Steroids 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 (Decadron®, Hexadrol®, Dexasone®) is the most commonly used steroid.

Drugs that help stomach emptying and so relieve feelings of sickness Metoclopramide (Maxolon®) and domperidone (Motilium®) both work in this way and are commonly used. Domperidone can be given as suppositories.

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 which dissolves in the mouth (Buccastem®). Chlorporamazine is another drug that acts in the same way, but it's usually only used in advanced cancer when other anti-emetics 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 which 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 (used when someone is having difficulty swallowing).

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

Neurokin inhibitor Aprepritant (Emend) is a new drug which is given along with steroids and a 5HT3 inhibitor to control sickness caused by chemotherapy (particularly with a drug called cisplatin). Aprepritant works by blocking a chemical which acts on receptors called neurokins and causes sickness.

Possible side effects Back to top

Sometimes anti-sickness drugs may cause side effects. Different drugs will have different side effects and each person may react differently. Some of the more common effects are listed below, alongside the drugs that may cause them.

Constipation Aprepritant, 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. These can be prescribed by your doctor.

Headaches Aprepritant, 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 Ondansetron, tropisetron (and dexamethasone when injected) 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 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 medicines can be prescribed to help.

Wakefulness (insomnia) 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.

Twitching Metoclopramide may cause muscle twitching which affects different parts of the body, including the face, neck and shoulders. This side effect 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 might like to do for yourself Back to top

Avoid eating or preparing food when you feel sick.

• 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 beer) can help some people.
• Don't drink a lot just before you eat.

Relaxation This can be helpful in coping with nausea. Using relaxation| tapes or taking part in activities that you find relaxing may be useful.

Acupuncture This involves the placing of thin, sterile needles into the skin to affect energy points. It is part of traditional Chinese medicine. Seabands (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.

References Back to top

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

• Martindale: The Complete Drug Reference (35th edition). Sweetman et al. Pharmaceutical Press, 2006.
• British National Formulary (57th edition). British Medical Association and Royal Pharmaceutical, Society of Great Britain, September 2008.
• Oxford Textbook of Palliative Medicine (3rd edition). Doyle et al. Oxford University Press, 2004.

For further references, please see the general bibliography|.