The U.S. Food and Drug Administration (FDA) has issued warning letters to three companies that manufacture and market mouthwash products whose labels make claims about removing plaque above the gum line or promoting healthy gums.

No such benefits have been demonstrated, the FDA maintains.

Warning letters were sent to Johnson & Johnson (Listerine Total Care Anticavity Mouthwash), CVS Corp. (CVS Complete Care Anticavity Mouthwash) and Walgreen Co. (Walgreen Mouth Rinse Full Action).