Sumac, referring generally to species from the genus Rhus (such as Rhus coriaria), has a long history of use in traditional medicine systems, particularly in the Middle East and Mediterranean regions. In some traditional practices, sumac was considered to have diuretic properties, and thus it was occasionally used to help reduce swelling or fluid accumulation associated with edema. However, these uses are based on empirical folk knowledge rather than systematic scientific research.

The available historical documentation, such as old herbal texts and ethnobotanical surveys, sometimes mention sumac's use for urinary and renal complaints, which may include edema as a symptom. Nevertheless, there is a lack of clinical trials or robust pharmacological studies directly evaluating sumac’s efficacy in the treatment or management of edema in humans or animals. The few scientific studies that exist on sumac focus largely on its antioxidant, antimicrobial, and anti-inflammatory properties, not specifically on diuresis or fluid balance.

In summary, the use of sumac for edema is rooted in traditional medicine and anecdotal reports, but there is at best weak or indirect evidence supporting its effectiveness for this purpose. No authoritative clinical guidelines or contemporary scientific reviews recommend sumac for edema.