Nausea medicine

Types of nausea medicine

The medicines for nausea used 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:

• 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 common 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. (CTZ stands for chemoreceptor trigger zone.) It also speeds up the emptying of the gut. It is not usually used for more than a few days. The use of domperidone is strictly regulated following a 2014 warning about the risk of cardiac (to do with the heart) side-effects. It is no longer available over the counter and should only be used at the lowest effective dose for the shortest possible time.

• 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 is not 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.

When is nausea medicine 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 for nausea?

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 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 the separate leaflet called Motion Sickness (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 the separate leaflet called Morning Sickness in Pregnancy for more detail.

• Migraine: both metoclopramide and domperidone work well for nausea caused by a migraine. See the separate leaflet called Migraine Medication, Treatment and Prevention 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 the separate leaflet called Chemotherapy for more detail.

Side-effects of nausea medicine

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:

• Constipation.

• Headaches.

• Drowsiness or tiredness.

• Trouble with sleeping (insomnia).

• Indigestion.

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.