Eugenol, a compound primarily derived from clove oil, is sometimes used topically for canker sores (aphthous ulcers) due to its analgesic and anti-inflammatory properties. The scientific evidence supporting its use is modest but present. Eugenol has long been used in dentistry for its local anesthetic effect and is a component of some over-the-counter dental pain relief products. Its mechanism is thought to involve the inhibition of prostaglandin synthesis, thereby reducing pain and inflammation at the site of application.

A small number of clinical studies and case reports suggest that topical application of eugenol or clove oil can provide temporary pain relief for oral mucosal lesions, including canker sores. For example, a study published in the Journal of Dentistry (2006) found that a eugenol-based paste provided symptomatic relief similar to that of standard treatments for aphthous ulcers. However, these studies are generally limited in size and scope, and larger, well-designed clinical trials are lacking.

While eugenol's analgesic and anti-inflammatory effects are scientifically recognized, its direct effectiveness for canker sore healing, as opposed to mere symptom relief, is less well established. Moreover, topical use of eugenol can sometimes cause irritation or allergic reactions in sensitive individuals. In summary, there is some scientific basis for the use of eugenol as a symptomatic treatment for canker sores, but the quality and quantity of the evidence are limited.