Heal-All (Prunella vulgaris), also known as self-heal, has a long history of traditional use in herbal medicine for various minor wounds and oral conditions, including canker sores (aphthous ulcers). Folk medicine practitioners have utilized the herb for its purported anti-inflammatory, astringent, and wound-healing properties. The plant has been applied as a mouthwash or in poultice form to help soothe oral mucosa and promote the healing of mouth ulcers. Historical texts and ethnobotanical surveys document its use in Europe, Asia, and North America for oral and throat ailments.

From a scientific perspective, Prunella vulgaris contains compounds such as rosmarinic acid, flavonoids, and tannins, which possess anti-inflammatory, antimicrobial, and antioxidant activities in vitro. However, direct clinical evidence supporting its efficacy specifically for canker sores in humans is limited. Few, if any, controlled clinical trials have evaluated its effectiveness for this indication. Most modern references to its use for canker sores cite historical and traditional practices rather than robust scientific validation. As such, its use is primarily justified by tradition, with a modest evidence rating reflecting the lack of high-quality clinical research.