The Collaborative Perinatal Project reported 197 first-trimester exposures to guaifenesin. Fourteen malformations were reported for a relative risk not significantly different from 1.0.

In a review of 229,101 deliveries to Michigan Medicaid patients, 141 first-trimester exposures to guaifenesin and 349 exposures anytime during pregnancy were recorded. A total of 9 birth defects were reported with first trimester exposure (6 expected) and included 2 cardiovascular defects. These data do not support an association between guaifenesin and birth defects. (written communication, Franz Rosa, MD, Food and Drug Administration, 1994)

Guaifenesin has been assigned to pregnancy category C. by the FDA. There are no controlled data in human pregnancy. Guaifenesin is only recommend for use during pregnancy when benefit outweighs risk.

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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.

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