Nausea is the unpleasant feeling that you need to be sick (vomit). There are many causes of nausea. Various medicines are available to treat nausea. They work in different ways to one another. Medicines to treat nausea are not usually started until your doctor is sure what has caused your nausea. This is because knowing the cause helps your doctor to choose the right medicine for you. Medicines for nausea are usually only needed for a few days. Most people are able to take these medicines.
What is nausea and what causes it?
Nausea is the feeling that you need to be sick (vomit). There is an area of the brain called the vomiting centre that controls the feeling of nausea and the need to vomit. It receives signals from other parts of the body such as the gut and the part of the ear that controls balance (the vestibular system). It also receives signals from other parts of the brain such as an area called the chemoreceptor trigger zone (CTZ). These signals have an effect on the vomiting centre in the brain and this is why you feel nausea and a need to vomit.
There are many conditions that can cause nausea. Some of the more common ones include:
- Tummy bugs (gastroenteritis).
- Ear problems.
- Motion sickness (travel sickness - feeling sick in a car, bus, boat, train or plane).
Other rare causes of nausea include:
- Growths (tumours) in the brain or gut.
- Infections of the brain (for example, meningitis).
Medicines can cause nausea as a side-effect:
- Some medicines, when taken in normal doses, may cause nausea - for example:
- Strong painkillers such as codeine and morphine.
- Some antidepressants.
- Medicines used to treat cancer (chemotherapy).
- Some medicines can cause nausea if the dose is too much for you - for example, digoxin (a medicine for the heart) or medicines that treat epilepsy.
- Nausea can also occur in some people after they have had surgery. This may be caused by the surgery itself or by the anaesthetic.
What are medicines for nausea and how do they work?
Medicines to treat nausea are used to prevent the feeling of sickness (nausea) and to stop you from being sick (vomiting). They are sometimes called antiemetics. Some of these medicines work on the gut and speed up how quickly food moves through it. Other medicines work on the brain and block signals to the vomiting centre. Listed below are some of the more commonly prescribed medicines for nausea:
- Cinnarizine, cyclizine, promethazine - these medicines belong to a group of medicines called antihistamines. The exact way that they work is not fully understood. It is thought that antihistamines block histamine 1 (H1) receptors in the area of the brain which creates nausea in response to chemicals in the body. They are thought to work well for nausea caused by a number of conditions including ear problems and motion (travel) sickness.
- Hyoscine - this medicine works by blocking a chemical in the brain called acetylcholine. It is a type of medicine called an antimuscarinic (or anticholinergic). It works well for nausea caused by ear problems and motion sickness.
- Chlorpromazine, haloperidol, perphenazine, prochlorperazine, levomepromazine - these medicines work by blocking a chemical in the brain called dopamine. They are useful for nausea that is caused by some cancers, radiation, and opiate medicines such as morphine and codeine. Prochlorperazine (or brand name Stemetil®) is one of the most used medicines for nausea. It works for many causes of nausea, including vertigo, ear problems and sickness in pregnancy.
- Metoclopramide - this medicine works directly on your gut. It eases the feelings of sickness by helping to empty the stomach and speed up how quickly food moves through the gut. It is often used for people with sickness due to gut problems or migraine. It is not usually used for more than a few days.
- Domperidone - this medicine works on the CTZ. It also speeds up the emptying of the gut. It is not usually used for more than a few days.
- Dexamethasone - this is a steroid medicine. It is a man-made version of a natural hormone produced by your own body. Dexamethasone has a wide range of actions on many parts of the body. The reason why it reduces nausea isn't clear.
- Granisetron, ondansetron, and palonosetron - these medicines work by blocking a chemical called serotonin (5-HT) in the gut, and the brain. Serotonin (5-HT) has an action in the gut and the brain to cause nausea. These medicines are useful for controlling nausea and vomiting caused by chemotherapy.
- Aprepitant and fosaprepitant - these are newer medicines and work by blocking a chemical that acts on neurokinin receptors in the body to cause nausea. They are sometimes called neurokinin-1 receptor antagonists. They are usually given to people on a certain type of chemotherapy.
- Nabilone - it is still not clear how this medicine works to control nausea. It is normally prescribed for people who are having chemotherapy.
Medicines for nausea are available as tablets capsules, liquids, suppositories and skin patches. Some are given as injections into the muscle or directly into the vein. Some of these medicines are also available as tablets that dissolve in the mouth against the gum. They are called buccal tablets. These medicines come in various different brand names.
When are medicines for nausea and vomiting prescribed?
Medicines for nausea are usually only prescribed once your doctor is sure what is causing your feeling of sickness (nausea). This is because, in a lot of cases, if you treat the condition causing your nausea, it will go away. For example, if your nausea is caused by taking too much of a particular medicine, your doctor will reduce the dose and your nausea will often go away. If the cause of your nausea is not known, your doctor can still prescribe a medicine for you but it is much better to know what the cause is so the right medicine can be chosen.
Which medicine is usually prescribed?
The choice of medicine depends on various factors, including:
- What is causing your feeling of sickness (nausea).
- Whether you have any other medical conditions.
- Whether you are pregnant.
- Possible side-effects of the medicines.
It is not possible to list all of the conditions that can cause nausea and which treatments are usually prescribed. However, some examples include:
- Motion (travel) sickness: hyoscine is the most effective medicine for motion sickness. Promethazine, cyclizine, or cinnarizine also work well. See separate article called Motion (Travel) Sickness for more detail.
- Pregnancy: if you are pregnant, your doctor will usually prefer not to treat nausea and being sick (vomiting) with medicines unless the symptoms are severe. However, if it is decided that you need treatment, generally promethazine, prochlorperazine, or metoclopramide may be prescribed. This is because they are not thought to harm the unborn baby. See separate leaflet called Sickness and Vomiting in Pregnancy for more detail.
- Migraine: both metoclopramide and domperidone work well for nausea caused by a migraine. See separate article called Medicines to Treat Migraine Attacks for more detail.
- Chemotherapy: it is not unusual to take a combination of different medicines to control nausea and vomiting if you have chemotherapy. Some chemotherapy medicines are more likely than others to cause nausea and vomiting. If you have chemotherapy that has a low risk of nausea, your doctor will usually prescribe metoclopramide or domperidone. If you have chemotherapy that has a high risk of nausea, three medicines that work in a different way to each other may be prescribed - for example, ondansetron, dexamethasone, and aprepitant. See separate article called Chemotherapy with Cytotoxic Medicines for more detail.
How should I take these medicines?
The way these medicines are taken depends on what is causing your feeling of sickness (nausea). For motion (travel) sickness it is best to take these medicines half an hour before you travel. This allows the medicine some time to work and prevent the feeling of nausea. For people who have chemotherapy, the doctor may advise you to take these medicines the day before you come to hospital for your treatment.
Sometimes, if you are very ill you may not be able to swallow tablets, capsules or liquids. In this case your doctor may decide to try another way of giving you these medicines. For example, you can have a skin patch, a medicine that is inserted into the back passage (suppository) or a tablet that dissolves in the mouth. If nausea and being sick (vomiting) are severe, your doctor may give you an injection.
For more information, see the leaflet that comes with your medicine.
What is the usual length of treatment?
Usually medicines to treat nausea are only taken for a short time, until the cause of the feeling of sickness (nausea) has been treated, or you get better. For example, if your nausea is caused by an ear infection, you will only need to take these medicines for a few days, until the symptoms have eased. For migraine, you may only need to take the medicine once or twice with each attack.
What about side-effects?
It is not possible to list all the possible side-effects of each of these medicines in this leaflet. However, as with all medicines, there are a number of side-effects that have been reported. To see the side-effects specific to your medicine, see the information leaflet that came with your medicine.
Common side-effects may include:
- Drowsiness or tiredness.
- Trouble with sleeping (insomnia).
However, the side-effects are different with each different medicine. Most side-effects are not serious and each person may react differently to these medicines. Usually most people do not get the side-effects listed; however, they can happen to some people.
Who cannot take medicines for nausea?
There are very few people who cannot take a medicine for nausea. If one medicine has caused a side-effect or there is a reason you cannot take one, your doctor can choose a different type of medicine that will suit you.
Can I buy medicines for nausea?
You can buy some medicines to treat nausea from your pharmacy. You can only buy them to treat motion (travel) sickness. Medicines that you can buy from your local pharmacy include hyoscine (Kwells® and Joy Rides®) and cinnarizine (Stugeron®).
How to use the Yellow Card Scheme
If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at the following web address: www.mhra.gov.uk/yellowcard.
The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that medicines or any other healthcare products may have caused. If you wish to report a side-effect, you will need to provide basic information about:
- The side-effect.
- The name of the medicine which you think caused it.
- Information about the person who had the side-effect.
- Your contact details as the reporter of the side-effect.
It is helpful if you have your medication - and/or the leaflet that came with it - with you while you fill out the report.
Dr Mary Harding
Dr Helen Huins