Sicilian Sumac (Rhus coriaria) has been traditionally used in Mediterranean herbal medicine for various ailments, but in recent years, scientific studies have specifically investigated its efficacy in treating canker sores (recurrent aphthous stomatitis). The primary rationale for its use is based on its demonstrated anti-inflammatory, antimicrobial, and antioxidant properties. Several controlled clinical trials, including a randomized, double-blind, placebo-controlled study published in 2020 in the journal BMC Complementary Medicine and Therapies, have shown that a topical sumac extract gel can significantly reduce pain, lesion size, and healing time in patients with canker sores compared to placebo. These effects are attributed to the high content of polyphenols, flavonoids, and tannins in sumac, which help modulate inflammatory pathways and inhibit microbial growth, both relevant to the pathophysiology of aphthous ulcers.

While the amount of research is still limited and most studies are of moderate size and short duration, the available evidence suggests a moderate level of scientific support for the topical use of Sicilian sumac in the management of canker sores. However, further large-scale, high-quality clinical trials are needed to establish standardized dosages and long-term safety. In summary, the use of Sicilian sumac is supported by both traditional use and emerging scientific evidence, but current scientific validation rates as moderate (3/5) based on existing published studies.