Nymphaea nouchali (also known as blue lotus or star lotus) has a long history of use in traditional medicine systems, particularly in South and Southeast Asia. In Ayurveda and some folk medicine traditions, various parts of the plant—such as the rhizomes, seeds, and flowers—have been used to manage conditions involving swelling and fluid retention, which are characteristic of edema. The traditional rationale is largely based on the plant's purported diuretic properties, which could theoretically help in reducing excess fluid accumulation in tissues.

However, the scientific literature directly supporting the use of Nymphaea nouchali for edema is limited. While some in vitro and animal studies have identified mild diuretic effects and antioxidant activities in extracts of the plant, these findings are preliminary and do not equate to clinical proof of efficacy in treating edema in humans. Furthermore, robust clinical trials or well-documented pharmacological evidence are lacking. Thus, the use of Nymphaea nouchali for edema is primarily justified by traditional use, with only low-level scientific support at this time.