A peroxyl rinse is a mild antiseptic used in the mouth to relieve minor mouth irritation, such as canker/cold sores, gingivitis, dentures, and orthodontic appliances. It works by releasing oxygen, causing foaming to remove mucus and clean the area. To use, mix 1 part 3% peroxide solution with 2 parts water, swish for 30 seconds, and then spit out. ^webmd.com+1 ^{1 2}