Peppermint (Mentha piperita) is commonly used in various forms (essential oil, inhalations, teas) to alleviate symptoms of sinus congestion. There is some scientific rationale for its use based largely on its primary active constituent, menthol. Menthol is known to produce a cooling sensation and has a subjective effect of making breathing feel easier. Some studies indicate that menthol can activate cold-sensitive receptors in the nose and upper airways, which can create a perception of improved airflow, though it does not actually decongest or reduce nasal resistance physiologically. A few small clinical studies and reviews have concluded that while menthol and peppermint oil do not significantly change objective measures of nasal airflow, they can make patients feel less congested.

Additionally, peppermint has mild antispasmodic and anti-inflammatory properties, which may help soothe irritated mucous membranes. Traditional uses and anecdotal reports also support inhalation of peppermint oil for congestion, but robust clinical trials are lacking. Safety concerns exist regarding direct application of undiluted essential oil, especially in children, due to risk of respiratory distress.

In summary, the evidence for peppermint's ability to relieve sinus congestion is limited and mainly subjective, rather than based on objective physiological changes. Therefore, while there is some scientific support, the overall evidence quality is low.