Good mouthwashes for canker sores include Listerine and medicated mouthwashes containing chlorhexidine gluconate, states the Massachusetts Dental Society. A sage and thyme tea rinse is a natural alternative. Place a few spoonfuls in a cup of hot water, cool it to room temperature, rinse for about 60 seconds and expectorate.
Naturopathic practitioners consider sage and thyme to have antiseptic qualities, notes the Massachussets Dental Society. Since chlorhexidine gluconate can stain the teeth, patients should consult their dentists or physicians before using it. Rinsing the mouth for about 60 seconds with a teaspoon of salt dissolved in 8 ounces of warm water is inexpensive and totally safe, although as of 2015, it is not established as an effective canker sore treatment.