Scallion (Allium fistulosum), also known as green onion, has been used in traditional medicine systems, particularly in East Asia, for a range of conditions, including edema (swelling due to fluid retention). In Traditional Chinese Medicine (TCM), scallion is believed to have warming properties and is used to promote sweating and resolve “wind-cold” conditions. Some TCM practitioners have historically recommended scallion to support mild cases of edema, often as part of herbal formulas intended to promote urination or disperse retained fluids.

However, there is little to no robust scientific evidence supporting the efficacy of scallion specifically for the treatment of edema. Modern research on scallion has focused primarily on its antimicrobial, antioxidant, and cardiovascular effects, with very limited investigation into its impact on fluid retention or diuretic activity. Any diuretic or anti-edematous properties are not well-documented in peer-reviewed scientific literature. Thus, while the traditional use exists, evidence for its effectiveness is weak, and it is not recognized as a standard treatment for edema in evidence-based medicine.

In summary, scallion's use for edema is based primarily on traditional practices, with minimal scientific validation. Anyone considering herbal remedies for edema should consult with a qualified healthcare professional.