Rat feeding studies with promethazine at doses of 2.1 to 4.2 times the maximum recommended human dose have failed to reveal evidence of teratogenicity, but daily intraperitoneal doses of 25 mg/kg have produced fetal mortality in rats. Although antihistamines have produced fetal mortality in rodents, the pharmacological effects of histamine in the rodent do not parallel those in man. There are no controlled data in human pregnancy.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

Benefit should outweigh risk

US FDA pregnancy category: C

Comments:
-Promethazine administered 2 weeks prior to delivery may inhibit platelet aggregation in the newborn.
-Many cough syrups contain alcohol, be sure to check labels and avoid alcohol containing products.

See references

Based on the low molecular weight of dextromethorphan some passage into breast milk probably occurs. However, maternal use of dextromethorphan products that do not contain alcohol are probably safe to use during breast-feeding. Phenothiazine derivatives are minimally excreted in breastmilk; although specific data on excretion of promethazine is not available. A less potent histamine blocking is generally preferred in nursing mothers.

Benefit should outweigh risk

Excreted into human milk: Unknown (dextromethorphan); Unknown (promethazine)
Excreted into animal milk: Data not available (dextromethorphan); Data not available (promethazine)

Comments:
-Many cough syrups contain alcohol, be sure to check labels and avoid alcohol containing products.
-Promethazine can inhibit prolactin release and may interfere with lactation.

See references