Several herbs are useful in the treatment of cranker sores.
Most of them contain tannins and have other wound healing properties. Tannin, the common name for tannic acid, is a constituent of many plants and gives foods an astringent taste. An antiseptic with broad-spectrum antibacterial and antiviral action, it's especially helpful for treating mouth sores, which could be caused by a bacterium, a fungus, a virus or an allergy. Gargle with calendula tea or goldenseal tea to help canker sores heal. Let this mixture steep for ten minutes.