Antiemetic (Antihistamine H₁ Antagonist) Pregnancy: In the absence of definitive human data, use in pregnancy is not advised. Breast-feeding: cyclizine is excreted in human milk (amount not quantified).

Cyclizine

Brand names: Valoid

Cyclizine is a sedating antihistamine (H1-receptor antagonist) with antiemetic properties, used to prevent and treat nausea and vomiting, including that associated with vestibular disorders, opioids and palliative care.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 50 mg

Route: Oral

Frequency: May be repeated up to three times a day

To prevent motion sickness, cyclizine should be taken about one to two hours before departure. Elderly: normal adult dosage is appropriate (no specific studies in the elderly). Children 6-12 years: 25 mg orally, up to three times a day. Children over 12 years: 50 mg orally, up to three times a day. Not recommended for children under 6 years.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any excipient
Acute alcohol intoxication (the anti-emetic properties of cyclizine may increase the toxicity of alcohol)

Side effects

Somnolence / drowsiness
Dry mouth, nose and throat
Constipation
Blurred vision
Tachycardia / palpitations

Interactions

Alcohol and other CNS depressants (additive effects: hypnotics, tranquillisers, anaesthetics, antipsychotics, barbiturates)
Pethidine (cyclizine enhances its soporific effect)
Opioid analgesics (cyclizine may counteract their haemodynamic benefits)
Other anticholinergic/antimuscarinic drugs (e.g. atropine, tricyclic antidepressants and MAOIs) — additive antimuscarinic effects
Ototoxic drugs such as aminoglycoside antibacterials (cyclizine may mask warning signs of ototoxic damage)

Clinical monograph

How it works

It blocks histamine H1 receptors and has anticholinergic activity acting on the vomiting centre and vestibular pathways to suppress nausea and vomiting.

Prescribing in practice

Its antimuscarinic effects mean it should be used with caution in older people and avoided where there is severe heart failure, urinary retention, prostatic enlargement or angle-closure glaucoma.
Rapid intravenous injection can cause unpleasant sensations and transient haemodynamic effects, and it has recognised potential for misuse.
It causes drowsiness, which is additive with alcohol and other CNS depressants.

Monitoring

No routine monitoring is required; review antiemetic response and watch for anticholinergic and sedative effects, especially in older patients.

Counselling the patient

This medicine can make you drowsy, so take care with driving or operating machinery.
Avoid alcohol while taking it.
Tell your team if you have difficulty passing urine or notice a dry mouth or blurred vision.

Evidence & guidelines

Cyclizine is a long-established antiemetic in UK practice for nausea and vomiting including vestibular and opioid-related causes, with antimuscarinic cautions well documented.

Reference: NICE NG121 Nausea and Vomiting in Pregnancy; Palliative Care Formulary (PCF) 7th Edition; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways