Meclizine and Pregnancy
In animal studies on pregnancy and meclizine, the risk of cleft palate was increased when high doses of the medication were given to pregnant rats. However, this does not appear to be a problem with humans. Human studies generally suggest that antihistamines (such as meclizine) are relatively safe for use in women who are expecting.
Is Meclizine Safe During Pregnancy?
Meclizine hydrochloride (Antivert®, Bonine®, Dramamine® Less Drowsy Formula) is an antihistamine medication approved to treat motion sickness and vertigo. Sometimes, antihistamines like meclizine are used "off-label" for the treatment of severe morning sickness. This medication seems to be relatively safe for use during pregnancy, although the full effects in humans are not currently known.
Pregnancy Category B
The U.S. Food and Drug Administration (FDA) uses a pregnancy category system to classify the possible risks to a fetus when a specific medicine is taken during pregnancy. Pregnancy Category B is given to medicines that have not been adequately studied in pregnant humans but do not appear to cause harm to the fetus in animal studies. Medications that have been shown to be safe for use in pregnancy in humans (but have caused problems in laboratory animals) are also given a Category B rating.
In studies, giving very large doses of meclizine to pregnant rats appeared to increase the risk of cleft palate. However, this does not appear to be a problem with meclizine use in humans.
In general, in human studies (which have not been adequate enough to fully characterize the safety of the medication), antihistamines seem to be fairly safe for use during pregnancy. It should be noted that the use of antihistamines in general during the last two weeks of pregnancy seems to increase the risk of retinopathy of prematurity (an eye problem in premature infants that can lead to blindness).