Risk Factor: BM
Class: Gastrointestinal agents/ Antiemetics
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.
- Mellin GW, Katzenstein M. Meclozine and fetal abnormalities. Lancet 1963;1:2223.
- Heinonen OP, Slone D, Shapiro S. Birth Defects and Drugs in Pregnancy. Littleton, MA:Publishing Sciences Group, 1977.
- Watt LO. Oxytocic effects of dimenhydrinate in obstetrics. Can Med Assoc J 1961;84:5334.
- Rotter CW, Whitaker JL, Yared J. The use of intravenous Dramamine to shorten the time of labor and potentiate analgesia. Am J Obstet Gynecol 1958:75:11014.
- Scott RS, Wallace KH, Badley DN, Watson BH. Use of dimenhydrinate in labor. Am J Obstet Gynecol 1962;83:258.
- Humphreys DW. Safe relief of pain during labor with dimenhydrinate. Clin Med (Winnetka) 1962;69:11658.
- Cooper K. Failure of dimenhydrinate to shorten labor. Am J Obstet Gynecol 1963;86:10413.
- Harkins JL, Van Praagh IG, Irwin NT. A clinical evaluation of intravenous dimenhydrinate in labor. Can Med Assoc J 1964;91:1646.
- Scott RS. The use of intravenous dimenhydrinate in labor. New Physician 1964;13:3027.
- Klieger JA, Massart JJ. Clinical and laboratory survey into the oxytocic effects of dimenhydrinate in labor. Am J Obstet Gynecol 1965;92:110.
- Hay TB, Wood C. The effect of dimenhydrinate on uterine contractions. Aust NZ J Obstet Gynaecol 1967;1:819.
- Shephard B, Cruz A, Spellacy W. The acute effects of Dramamine on uterine contractibility during labor. J Reprod Med 1976;16:278.
- Hara GS, Carter RP, Krantz KE. Dramamine in labor: potential boon or a possible bomb? J Kans Med Soc 1980;81:1346, 155.
- Gross S, Librach C, Cecutti A. Maternal weight loss associated with hyperemesis gravidarum: a predictor of fetal outcome. Am J Obstet Gynecol 1989;160:9069.