Foreword: I ask this only for mouthwashes with no alcohol; so please omit alcoholic mouthwashes (which may hurt the mouth and may have been claimed to cause cancer).
My grandmother uses the Crest Pro-Health Rinse which contains 'anti-microbial agent, cetylpyridinium chloride'. Yet USA Today in 2008 and CTV News in 2012 reported complaints that the mouthwash browns and stains teeth, and also numbs taste. From the CTV article:
The parent company of Crest, Proctor and Gamble, told CTV News that the ingredient Cetyl Pyridinium Chloride is what causes some people’s teeth to turn brown.
Dentist Shaireen Lalani says the stains are not permanent and can be removed with professional cleaning.
In some cases, Crest has reimbursed consumers to have their teeth professionally cleaned.
What are the risks to using such mouthwashes? Most mouthwashes recommend two rinses daily, but is this advice safe and correct? How often should they really be used?