Synopsis

Source of validity: Scientific
Rating (out of 5): 2

Alum (potassium aluminum sulfate) is traditionally used as a home remedy for canker sores, but there is also limited scientific evidence supporting its use. Alum acts as an astringent, which means it can help to shrink tissues and dry out the sore, potentially speeding healing and reducing pain. Several small clinical studies and case reports have investigated the topical application of alum powder or preparations for aphthous ulcers (canker sores). These studies generally suggest that alum may help reduce the size, pain, and duration of canker sores compared to controls, although the sample sizes are typically small and methodologies vary. For example, a 2013 randomized controlled trial found that alum-containing mucosal adhesive patches significantly reduced pain and healing time in patients with recurrent aphthous stomatitis compared to placebo. However, further high-quality studies are needed to confirm these findings.

Alum's mechanism is thought to involve protein precipitation and local tissue contraction, forming a protective layer over the ulcer. This reduces irritation from food and saliva, which may facilitate healing. However, alum can cause local irritation or a burning sensation, and long-term or excessive use is not recommended due to potential tissue damage. Major dental and medical organizations do not officially endorse alum for canker sores, but it remains an over-the-counter ingredient in some lozenges and topical preparations.

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