Chattanooga-based Chattem, maker of Allegra allergy medicine, provided a reasonable basis to claim that "only Allegra combines fast, non-drowsy, 24-hour relief," the Council of Better Business Bureaus said.
But the group's national advertising division recommends Chattem modify the claim to make clear that Allegra takes effect an hour after being taken on the first day.
It recommends Chattem discontinue broadcast ads that suggest the product gives immediate relief.
The claims were challenged by Schering-Plough Healthcare Products, maker of competitor Claritin.
Chattem in a statement said the company appreciated the group's "careful review of the scientific record and relevant precedent establishing that Allegra begins working at hour one and Claritin begins working at three hours."