Cyclizine is a type of medicine called an antihistamine. It is used to prevent and treat nausea and vomiting associated with middle ear disorders, motion (travel sickness) and following surgery or radiotherapy.
Vomiting is controlled by an area of the brain called the vomiting centre. The vomiting centre is responsible for causing feelings of sickness (nausea) and for the vomiting reflex. It is activated when it receives nerve messages from the vestibular apparatus in the middle ear.
The vestibular apparatus provides continual feedback to the brain about our body position. When something disturbs the vestibular apparatus, such as head movement following surgery or motion when travelling by boat or car, nerve signals are sent from the vestibular apparatus to the vomiting centre. This can cause sensations such as nausea, dizziness or spinning sensations (vertigo) and the reflex of vomiting.
Cyclizine works by blocking histamine and muscarinic receptors in the vomiting centre, which prevents the vomiting centre from receiving nerve messages from the vestibular apparatus. This prevents disturbances in the middle ear from activating the vomiting centre and causing nausea, vertigo and vomiting.
Cyclizine may also prevent the vomiting centre from receiving messages from an area of the brain called the chemoreceptor trigger zone (CTZ). The CTZ is stimulated by agents circulating in the blood, for example anaesthetics and opioid painkillers such as morphine. Cyclizine helps prevent these agents from activating the vomiting centre and causing sickness.
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.
For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start taking this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to make sure that the combination is safe.
There may be an increased risk of drowsiness if this medicine is taken with any of the following (which can also cause drowsiness):
If this medicine is taken with other medicines that have antimuscarinic effects there may be an increased risk of side effects such as blurred vision, dry mouth and constipation. Other medicines with antimuscarinic effects include the following:
Cyclizine tablets used to be marketed under the brand name Valoid tablets. However, these are no longer available and the tablets are currently only available generically (ie without a brand name).