An antisickness antihistamine

Cyclizine

An antihistamine anti-sickness medicine used to prevent and treat nausea, vomiting and vertigo; it commonly causes drowsiness and is generally used short-term.

What is Cyclizine?

Cyclizine is an antihistamine-type anti-sickness (antiemetic) medicine used in the UK to prevent and treat nausea, vomiting and vertigo, including motion sickness and sickness after surgery. It works on the part of the brain and inner ear that trigger sickness. It commonly causes drowsiness, is usually used short-term, and is occasionally misused because of its sedating effects.

Education and reference only. This is a plain-language guide to Cyclizine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.

Written by Meds Global Health Clinical Team · Clinically reviewed by Dr Muhammad Suffyan, MB BS, Founder & Clinical Director · Last reviewed · How we review
Class: Antiemetics → Brands: Valoid
Cyclizine (Antiemetics) — Meds Global Health reference card with 2D molecular structure
Cyclizine — Antiemetics. The image shows the active ingredient's 2D molecular structure.

What it is

Cyclizine is an older antihistamine that is used not for allergies but as an anti-sickness (antiemetic) medicine. It helps prevent and treat nausea, vomiting and the spinning sensation of vertigo, and is used for things like motion sickness, sickness after an operation, and nausea from inner-ear or balance problems. It comes as a tablet or an injection and works fairly quickly. Like other older antihistamines it tends to cause drowsiness, so it is generally used for short periods rather than continuously.

How it works

Feeling sick is triggered by signals reaching the brain's vomiting centre, including from the balance organs of the inner ear and the brain's chemical 'trigger zone'. Cyclizine blocks histamine and related (muscarinic) signalling on this pathway, which calms the messages that bring on nausea and vomiting. The same blocking action on the brain explains its main side effect of drowsiness.

Company & origin

Originated / developed by: A long-established antihistamine antiemetic, available in the UK as generic cyclizine and under the brand Valoid..

Cyclizine is an older antihistamine-type anti-sickness medicine long used in the UK to prevent and treat nausea, vomiting and vertigo.

Practical use

How to take Cyclizine

General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.

  • Take or use it as directed to prevent or settle nausea, vomiting or vertigo; for motion sickness, take it before travelling.
  • Expect drowsiness, and do not drive or operate machinery until you know how it affects you.
  • Avoid alcohol while taking it, as this adds to the drowsiness.
  • Sip water or use sugar-free gum if your mouth feels dry.
  • Use it short-term as advised rather than continuously, and tell your prescriber if the sickness is not settling.
  • Do not take more than directed or share it with others.

Weighing it up

Advantages & disadvantages of Cyclizine

Advantages

  • It is an effective, fast-acting anti-sickness medicine for nausea, vomiting and vertigo.
  • It is useful for motion sickness, inner-ear problems and sickness after surgery.
  • It comes as both a tablet and an injection for when swallowing is difficult or vomiting is severe.

Disadvantages

  • It commonly causes drowsiness, which can affect driving and daily activities.
  • It can cause a dry mouth and is used cautiously in older people and in glaucoma, prostate and heart conditions.
  • Because it is sedating, it is occasionally misused, so it is meant for short-term use.

Practical use

Good to know

Cyclizine commonly causes drowsiness, so do not drive or operate machinery until you know how it affects you, and avoid alcohol, which adds to the sedation. It also tends to cause a dry mouth and, like other antihistamines and antimuscarinics, is used cautiously in older people and in conditions such as glaucoma, prostate enlargement and heart problems. It is generally a short-term medicine for sickness rather than something to take indefinitely. Because it is sedating and can be pleasant for some people, it is occasionally misused, so it is used as directed and not shared.

Who should not take it / use with caution

  • People with severe heart failure, in whom it is generally avoided.
  • People with untreated narrow-angle glaucoma, significant prostate enlargement or urinary retention.
  • Used with caution in older people, and in epilepsy and liver problems.
  • Care in pregnancy and breastfeeding — used only on advice.

Monitoring

  • Review of whether the nausea, vomiting or vertigo is settling
  • Watching for excessive drowsiness, especially in older people
  • Checking it is still needed rather than being used long-term

Side effects

  • Drowsiness and a dry mouth are the most common.
  • Blurred vision, constipation and difficulty passing urine.
  • Restlessness or a faster heartbeat; confusion can occur, especially in older people.

Key interactions

  • Alcohol and other sedating medicines, such as sleeping tablets, strong painkillers and some antidepressants, add to the drowsiness.
  • Other antimuscarinic (anticholinergic) medicines add to dry mouth, constipation and confusion.
  • Tell your pharmacist about all your medicines, including ones bought over the counter for sleep or colds.

Available as: Tablets, and an injection.

Answers

Cyclizine: frequently asked questions

What is cyclizine used for?

It is an anti-sickness medicine used to prevent and treat nausea, vomiting and vertigo — for example motion sickness, sickness after an operation, and nausea from inner-ear or balance problems.

Will cyclizine make me drowsy?

Yes, drowsiness is common because cyclizine is an older, sedating antihistamine. Do not drive or operate machinery until you know how it affects you, and avoid alcohol, which makes it worse.

Can I take cyclizine for travel sickness?

Yes, it can be used for motion sickness and works best if taken before you travel. Bear in mind it can make you drowsy.

Is cyclizine addictive?

It is not addictive in the usual sense, but because it is sedating some people misuse it, so it is meant for short-term use as directed and should not be taken in larger amounts or shared with others.

What is the difference between cyclizine and Valoid?

They are the same medicine — cyclizine is the active-ingredient name and Valoid is a brand name. Generic cyclizine contains the identical active ingredient.

The wider class

About Antiemetics

Cyclizine belongs to the antiemetics class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.

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Authoritative sources

  • BNF: Cyclizine.
  • NICE CKS: Nausea and vomiting.
  • electronic Medicines Compendium (SmPC): Cyclizine.

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