Indian Chrysanthemum (Chrysanthemum indicum) has a long history of use in traditional medicine systems such as Ayurveda and Traditional Chinese Medicine (TCM). In these systems, the plant is valued for its purported anti-inflammatory, antimicrobial, and cooling properties. Specifically for canker sores (aphthous ulcers), traditional practitioners have employed infusions, decoctions, or topical preparations of chrysanthemum to soothe oral inflammation and promote healing. The rationale is often grounded in the theory that canker sores are caused or aggravated by "heat" or inflammation in the body, which chrysanthemum is believed to counteract.

Scientific studies directly investigating the efficacy of Chrysanthemum indicum for canker sores are limited and mostly preclinical. Some in vitro and animal studies have shown that extracts of the plant possess anti-inflammatory and antimicrobial activities, which could, in theory, help with oral ulcers. However, there are no robust clinical trials specifically validating its effectiveness for canker sores in humans. Therefore, its use is primarily justified by tradition rather than strong scientific evidence. The evidence rating is moderate (2/5) given the combination of longstanding traditional use and some supportive but indirect laboratory data.