Trimeprazine

 Risk Factor: C
 Class: ANTIHISTAMINES

Contents of this page:

Fetal Risk Summary
Breast Feeding Summary
References
Questions and Answers

Fetal Risk Summary

Trimeprazine is a phenothiazine antihistamine that is primarily used as an antipruritic. The Collaborative Perinatal Project monitored 50,282 mother-child pairs, 14 of whom had 1st-trimester exposure to trimeprazine (1, p. 323). From this small sample, no evidence was found to suggest a relationship to large categories of major or minor malformations or to individual malformations. For use anytime in pregnancy, 140 exposures were recorded (1, p. 437). Based on defects in five children, a possible association with malformations was found, but the significance of this is unknown.

In a 1971 study, infants of mothers who had ingested antihistamines during the 1st trimester actually had significantly fewer abnormalities when compared with controls (2). Trimeprazine was the eighth most commonly used antihistamine.

Breast Feeding Summary

Trimeprazine is excreted into human milk but the levels are too low to produce effects in the infant (3).

References

1. Heinonen OP, Slone D, Shapiro S. Birth Defects and Drugs in Pregnancy. Littleton, MA: Publishing Sciences Group, 1977.
2. Nelson MM, Forfar JO. Associations between drugs administered during pregnancy and congenital abnormalities. Br Med J 1971;1:5237.
3. O'Brien TE. Excretion of drugs in human milk. Am J Hosp Pharm 1974;31:84454.