Risk Factor: B
Class: Gastrointestinal agents/ Antiemetics

Contents of this page:
Fetal Risk Summary
Breast Feeding Summary

Fetal Risk Summary

Cyclizine is a piperazine antihistamine that is used as an antiemetic (see also Buclizine and Meclizine for closely related drugs). The drug is teratogenic in animals but apparently not in humans. In 111 patients given cyclizine during the 1st trimester, no increased malformation rate was observed (1). Similarly, the Collaborative Perinatal Project found no association between 1st trimester cyclizine use and congenital defects, although the number of exposed patients (N=15) was small compared to the total sample (2). The Food and Drug Administration’s OTC Laxative Panel acting on this data concluded that cyclizine is not teratogenic (3). In 1974, investigators searching for an association between antihistamines and oral clefts found no relationship between this defect and the cyclizine group (4). Finally, a retrospective study in 1971 found that significantly fewer infants with malformations were exposed to antihistamines/antiemetics in the 1st trimester as compared to controls (5). Cyclizine was the fifth most commonly used antiemetic.

An association between exposure during the last 2 weeks of pregnancy to antihistamines in general and retrolental fibroplasia in premature infants has been reported. See Brompheniramine for details.

Breast Feeding Summary

No data are available.



  1. Milkovich L, Van den Berg BJ. An evaluation of the teratogenicity of certain antinauseant drugs. Am J Obstet Gynecol 1976;125:2448.
  2. Heinonen OP, Slone D, Shapiro S. Birth Defects and Drugs in Pregnancy. Littleton, MA:Publishing Sciences Group, 1977:323.
  3. Anonymous. Meclizine; cyclizine not teratogenic. Pink Sheets. FDC Rep 1974:T&G-2.
  4. Saxen I. Cleft palate and maternal diphenhydramine intake. Lancet 1974;1:4078.
  5. Nelson MM, Forfar JO. Associations between drugs administered during pregnancy and congenital abnormalities of the fetus. Br Med J 1971;1:5237.

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