Systematic (IUPAC) name
Clinical data
Trade names Marezine
AHFS/ Consumer Drug Information
Pregnancy cat. A (Au)
Legal status P/POM (UK) OTC (NL)
Routes Oral, IM, IV
Pharmacokinetic data
Metabolism N-demethylated to inactive norcyclizine[citation needed]
Half-life 20 hours
CAS number 82-92-8 YesY
ATC code R06AE03
PubChem CID 6726
DrugBank APRD00061
ChemSpider 6470 YesY
KEGG D03621 YesY
Chemical data
Formula C18H22N2 
Mol. mass 266.381 g/mol
SMILES eMolecules & PubChem
 N(what is this?)  (verify)

Cyclizine is an antihistamine drug used to treat nausea, vomiting and dizziness associated with motion sickness, vertigo and post-operatively following administration of general anaesthesia and opioids.



Nausea, vomiting and dizziness associated with motion sickness, vertigo and post-operatively following administration of general anaesthesia and opioids. It is sometimes given in hyperemesis gravidarum (morning sickness) although the manufacturer advises avoid in pregnancy. Off licence use often occurs with specialists in hospitals to treat inpatients who have become severely dehydrated in pregnancy. An off-label use is as an opioid/opiate potentiator.[1]

The drug Diconal is a combination of cyclizine with the opioid dipipanone.[2] Dipipanone is a schedule I controlled substance in the US, due to its high abuse potential.


Its antimuscarinic action warrants caution in patients with prostatic hypertrophy, urinary retention, or glaucoma. Liver disease exacerbates its sedative effects.[1]

Adverse effects

Common (over 10%) – Drowsiness, xerostomia (dry mouth)

Uncommon (1% to 10%) – Headache, psychomotor impairment, and antimuscarinic effects such as urinary retention, diplopia (blurred vision), dermatitis, and gastro-intestinal disturbances.

Rare – Hypersensitivity reactions (bronchospasm, angioedema, anaphylaxis, rashes and photosensitivity reactions), extrapyramidal effects, dizziness, confusion, depression, sleep disturbances, tremor, liver dysfunction and hallucinations


As cyclizine hydrochloride 50 mg tablets and cyclizine lactate solution for intramuscular or intravenous injection (brand names: Valoid[1] in UK and Marezine, Marzine and Emoquil in US). Cyclizine HCl 25 mg is marketed as Bonine for Kids in the US.[3]


Cyclizine is a piperazine derivative with histamine H1-receptor antagonist (antihistamine) activity. The precise mechanism of action in inhibiting the symptoms of motion sickness is not well understood. It may have effects directly on the labyrinthine apparatus and on the chemoreceptor trigger zone. Cyclizine exerts a central anticholinergic (antimuscarinic) action.[1]


Cyclizine was developed in the American division of pharmacy company Burroughs Wellcome (today GlaxoSmithKline) during a research involving many drugs of the antihistamine group. Cyclizine was quickly clinically found as a potent and long-acting antiemetic. Company named the substance – or more precisely cyclizine's hydrochloride form which it usually appears in – "marezine hydrochloride" and started to sell it in the United States under trade name Marezine. Selling was begun in France under trade name Marzine in 1965.[4][5]

The substance received more credit when NASA chose it as a space antiemetic for the first occupied moon flight. Cyclizine was introduced to many countries as a common antiemetic. It is an over-the-counter drug in many countries because it has been well tolerated, although it has not been very much studied.[4]

Recreational use

Some people using methadone recreationally combine cyclizine with their methadone dose, a combination that is known to produce strong psychoactive effects.[6] It has also been used recreationally by teenagers for its anticholinergic effects to induce hallucinations.[7]

See also


  1. ^ a b c d "Valoid Tablets by Amdipharm". Electronic Medicines Compendium. Datapharm. 
  2. ^ "Diconal Tablets by Amdipharm". Electronic Medicines Compendium. Datapharm. 
  3. ^ "Bonine for Kids". Insight Pharmaceuticals. 
  4. ^ a b Sneader, Walter (2005). Drug discovery: a history. John Wiley & Sons. p. 404. ISBN 0-471-89979-8. 
  5. ^ Sittig, Marshall (1988). Pharmaceutical manufacturing encyclopedia. William Andrew. p. 406. ISBN 0-8155-1144-2. 
  6. ^ Ruben, S. M.; McLean, P. C.; Melville, J. (1989). "Cyclizine abuse among a group of opiate dependents receiving methadone". British journal of addiction 84 (8): 929–934. doi:10.1111/j.1360-0443.1989.tb00766.x. PMID 2775912.  edit
  7. ^ Bassett, K.; Schunk, J. E.; Crouch, B. I. (1996). "Cyclizine abuse by teenagers in Utah". The American Journal of Emergency Medicine 14 (5): 472–474. doi:10.1016/S0735-6757(96)90156-4. PMID 8765114.  edit