The FDA has sent a warning letter to Procter & Gamble notifying the company that its Vicks DayQuil Plus Vitamin C and Vicks Nyquil Plus Vitamin C are illegally marketed combinations of drug ingredients and a dietary ingredient. Both of the over-the-counter (OTC) medicines, which contain vitamin C in addition to several drug ingredients, are marketed as treatments for cold and flu symptoms. The FDA took the action against the Cincinnati-based company: To clarify that these single dosage form combinations of drug ingredients and dietary ingredients legally cannot be marketed because they have not been proven safe and effective, and Because the agency previously determined that there are insufficient data to show that vitamin C is safe and effective in preventing or treating the common cold. Under its OTC monograph system, the FDA allows some OTC drugs to be marketed without agency approval. Such drugs must comply with applicable monographs, which are regulations that set requirements for the drugs' labeling, formulations and indications. The two Vicks products do not comply with the applicable FDA monograph and must first be evaluated and approved under the FDA’s new drug approval process to be legally marketed. The FDA’s position on the regulatory status of OTC drug products that combine drug ingredients with dietary ingredients in a single dosage form has been described in previous warning letters issued in 2001 and 2008. The agency’s position on the marketing of vitamin C for preventing or treating the common cold also has been stated in a number of previous warning letters.