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Diphenhydramine / guaifenesin Pregnancy and Breastfeeding Warnings

Diphenhydramine / guaifenesin Pregnancy Warnings

Guaifenesin has been assigned to pregnancy category C by the FDA. There are no controlled data in human pregnancy.

Diphenhydramine has been assigned to pregnancy category B by the FDA. Animal studies have failed to reveal teratogenicity. The Collaborative Perinatal Project reported 595 first-trimester exposures and 2,948 exposures anytime during pregnancy. No relationship was found to large categories of malformations. Possible associations with individual malformation were found. One study reported a statistical relationship between diphenhydramine use in the first trimester and cleft palate. One case of withdrawal in an infant whose mother ingested 150 mg per day of diphenhydramine has been reported. This infant developed tremor on the fifth day of life which was treated with phenobarbital. Diphenhydramine-guaifenesin is only recommend for use during pregnancy when benefit outweighs risk.

A review of prenatal drug use in 3026 women with premature infants demonstrated an increased risk of retrolental fibroplasia with antihistamine use during the last two weeks of pregnancy. The dosage used or the particular antihistamine was not specified. The incidence of retrolental fibroplasia in premature infants exposed in utero to antihistamine during this time was 21% compared to 11% in premature infants not exposed.

Diphenhydramine has been shown to have oxytocic effects in animal and human uteri. One case report of a pregnant woman who ingested a large amount of diphenhydramine in an attempted suicide developed strong, regular uterine contractions that were halted by the administration of intravenous magnesium.

See references

Diphenhydramine / guaifenesin Breastfeeding Warnings

Diphenhydramine is excreted into human milk. Diphenhydramine may also inhibit lactation. The manufacturer recommends that due to the potential for serious adverse reactions in nursing infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.


There are no data on the excretion of guaifenesin into human milk. The manufacturer recommends that due to the potential for serious adverse reactions in nursing infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

See references

References for pregnancy information

  1. Saxen I "Letter: Cleft palate and maternal diphenhydramine intake." Lancet 1 (1974): 407-8
  2. Zierler S, Purohit D "Prenatal antihistamine exposure and retrolental fibroplasia." Am J Epidemiol 123 (1986): 192-6
  3. Brost BC, Scardo JA, Newman RB "Diphenhydramine overdose during pregnancy: lessons from the past." Am J Obstet Gynecol 175 (1996): 1376-7
  4. "Product Information. Humabid (guaifenesin)." Medeva Pharmaceuticals, Rochester, NY.
  5. Leathem AM "Safety and efficacy of antiemetics used to treat nausea and vomiting in pregnancy." Clin Pharm 5 (1986): 660-8
  6. Parkin DE "Probable Benadryl withdrawal manifestations in a newborn infant." J Pediatr 85 (1974): 580
  7. Heinonen O, Slone D, Shapiro S; Kaufman DW ed. "Birth Defects and Drugs in Pregnancy." Littleton, MA: Publishing Sciences Group, Inc. (1977): 297

References for breastfeeding information

  1. Covington TR, Lawson LC, Young LL, eds. "Handbook of Nonprescription Drugs. 10th ed." Washington, DC: American Pharmaceutical Association (1993):
  2. "Product Information. Benadryl (diphenhydramine)." Parke-Davis, Morris Plains, NJ.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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