Phenylephrine / promethazine Pregnancy and Breastfeeding Warnings

Brand names: Phenergan VC, Promethazine VC, Promethazine VC Plain

Medically reviewed by Drugs.com. Last updated on Aug 4, 2023.

Phenylephrine / promethazine Pregnancy Warnings

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.

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. In animal studies, exposure to phenylephrine 3 mg/day during the first half of pregnancy resulted in a significant number of litters with low birth weight; exposure during the second half of pregnancy may have contributed to perinatal wastage, prematurity, premature labor, and possibly fetal anomalies. 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.

See references

Phenylephrine / promethazine Breastfeeding Warnings

Benefit should outweigh risk

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

Comments:
-Many cough syrups contain alcohol, be sure to check labels and avoid alcohol containing products.
-Promethazine may interfere with the establishment of lactation and phenylephrine may decrease milk production; alternative agents may be preferred.

Based on the low molecular weight of phenylephrine, some passage into breast milk probably occurs. Animal data indicates that phenylephrine can decrease milk production, but there is no information in humans. 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.

See references