Piper retrofractum, also known as Javanese long pepper, has been traditionally used in various Southeast Asian and traditional medicine systems, such as Jamu in Indonesia and Ayurveda, for the management of respiratory ailments including sinus congestion. The use is typically based on its reputed properties as an expectorant and its warming, pungent qualities, which are believed to help clear mucus and facilitate breathing. In ethnobotanical literature, preparations containing Piper retrofractum are described for use in treating coughs, colds, and sinus issues, often in combination with other herbs.

However, there is a lack of robust modern scientific studies specifically validating its efficacy for sinus congestion. The evidence available is mostly anecdotal or based on traditional usage patterns rather than controlled clinical trials. Some phytochemical analyses indicate the presence of compounds such as piperine, which may have mild anti-inflammatory and decongestant effects, but direct studies on sinus congestion are lacking. Thus, the justification for its use in treating or supporting relief from sinus congestion is primarily traditional, with limited scientific backing at this time.