Marjoram (Origanum majorana) has been traditionally used in herbal medicine for respiratory conditions, including sinus infections. Folk remedies in Mediterranean and Middle Eastern cultures have utilized marjoram as an herbal tea, steam inhalation, or essential oil to alleviate symptoms such as nasal congestion and sinus discomfort. The rationale is largely based on marjoram's reputed anti-inflammatory, antimicrobial, and mild decongestant properties, which could theoretically help relieve sinus infection symptoms.

However, the scientific evidence supporting marjoram’s effectiveness specifically for sinus infections (acute or chronic rhinosinusitis) is limited. While some laboratory studies have shown that marjoram extracts and essential oil possess antimicrobial activity against certain bacteria and fungi, these findings have not been directly translated into clinical studies or trials involving patients with sinus infections. There are no well-designed clinical trials demonstrating marjoram’s efficacy for this particular condition.

In summary, while marjoram is used in traditional medicine practices for sinus-related ailments, its use is not strongly supported by scientific research. The evidence is primarily anecdotal and traditional, with only indirect support from basic laboratory studies on antimicrobial effects. Individuals considering marjoram for sinus infections should be aware of the lack of robust clinical data.