The U.S. Food and Drug Administration (FDA) has placed pseudoephedrine (the active ingredient in most decongestants) in risk category C. This means that although there are no studies linking the premature termination of pregnancy or birth defects to pseudoephedrine use in humans, there is evidence of an increased risk in some animal studies. Pregnant women should not take pseudoephedrine without first consulting their physician. In addition, women who become pregnant while taking the drug should alert their physician immediately.