Small, occasional doses of dimenhydrinate would not be expected to cause any adverse effects in breastfed infants. Larger doses or more prolonged use may cause effects in the infant or decrease the milk supply, particularly in combination with a sympathomimetic such as pseudoephedrine or before lactation is well established. Single bedtime doses after the last feeding of the day may be adequate for many women and will minimize any effects of the drug.
Dimenhydrinate is the 8-chlortheophyllinate salt of diphenhydramine.
One old study that used a biologic assay system reported that after a 100 mg intramuscular dose of diphenhydramine in four women, drug levels in milk were undetectable in two and 42 and 100 mcg/L in two others at one hour after the dose. Five hours after the dose, milk levels were undetectable in two women and 20 and 100 mcg/L in two others. No studies using modern assay methods have been reported.
Relevant published information was not found as of the revision date.
Effects in Breastfed Infants:
In one telephone follow-up study, mothers reported irritability and colicky symptoms in 10% of infants exposed to variousantihistaminesand drowsiness was reported in 1.6% of infants. None of the reactions required medical attention. In this study, irritability was reported in 1 infant of 7 exposed to dimenhydrinate in breastmilk.
Possible Effects on Lactation:
Antihistaminesin relatively high doses given by injection can decrease basal serum prolactin in nonlactating women and in early postpartum women. However, suckling-induced prolactin secretion is not affected byantihistaminepretreatment of postpartum mothers. Whether lower oral doses ofantihistamineshave the same effect on serum prolactin or whether the effects on prolactin have any consequences on breastfeeding success have not been studied.
1. Rindi V. La eliminazione degli antistaminici di sintesi con il latte e l'azione latto-goga de questi. Riv Ital Ginecol. 1951;34:147-57. 2. Ito S, Blajchman A, Stephenson M et al. Prospective follow-up of adverse reactions in breast-fed infants exposed to maternal medication. Am J Obstet Gynecol. 1993;168:1393-9. PMID:8498418 3. Messinis IE, Souvatzoglou A, Fais N et al. Histamine H1 receptor participation in the control of prolactin secretion in postpartum. J Endocrinol Invest. 1985;8:143-6. PMID:3928731 4. Pontiroli AE, De Castro e Silva E, Mazzoleni F et al. The effect of histamine and H1 and H2 receptors on prolactin and luteinizing hormone release in humans: sex differences and the role of stress. J Clin Endocrinol Metab. 1981;52:924-8. PMID:7228996
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