Dimenhydrinate in pregnancy and breastfeeding


Risk Factor: BM
Class: Gastrointestinal agents/ Antiemetics

Contents of this page:
Fetal Risk Summary
Breast Feeding Summary

Fetal Risk Summary

Dimenhydrinate is the chlorotheophylline salt of the antihistamine diphenhydramine. A prospective study in 1963 compared dimenhydrinate usage in three groups of patients: 266 with malformed infants and two groups of 266 each without malformed infants (1). No difference in usage of the drug was found between the three groups.

The Collaborative Perinatal Project monitored 50,282 mother-child pairs, 319 of which had 1st trimester exposure to dimenhydrinate (2, pp. 367370). For use anytime in pregnancy, 697 exposures were recorded (2, p. 440). In neither case was evidence found to suggest a relationship to large categories of major or minor malformations. Two possible associations with individual malformations were found, but their statistical significance is unknown. The defects noted were cardiovascular defects (five cases) and inguinal hernia (eight cases). Independent confirmation is required to determine the actual risk for these anomalies from dimenhydrinate (2, p. 440).

A number of reports have described the oxytocic effect of IV dimenhydrinate (3,4,5,6,7,8,9,10,11,12 and 13). When used either alone or with oxytocin, most studies found a smoother, shorter labor. However, in one study of 30 patients who received a 100-mg dose during 3.5 minutes, some (at least two, but exact number not specified) also showed evidence of uterine hyperstimulation and fetal distress (e.g., bradycardia and loss of beat-to-beat variability) (13). Due to these effects, dimenhydrinate should not be used for this purpose.

Dimenhydrinate has been used for the treatment of hyperemesis gravidarum (14). In 64 women presenting with the condition prior to 13 weeks’ gestation, all were treated with dimenhydrinate followed by various other antiemetics. Three of the newborns had integumentary abnormalities consisting of one case of webbed toes with an extra finger, and two cases of skin tags (one preauricular and one sacral). The defects were not thought to be related to the drug therapy (14).

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 reports describing the use of dimenhydrinate during lactation have been located. The molecular weight (about 470) is low enough, however, that excretion into milk should be expected. For a closely related product, see Diphenhydramine.



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