Phyllanthus fraternus has been investigated in several preclinical studies for its potential benefits in managing colitis, particularly in animal models. Research indicates that extracts of P. fraternus possess anti-inflammatory, antioxidant, and cytoprotective properties, which are relevant to the pathophysiology of colitis. In experimental studies using rats with chemically-induced colitis (for example, acetic acid or dextran sulfate sodium models), administration of P. fraternus extracts has been shown to reduce inflammation, decrease oxidative stress markers, and improve histopathological features of the colon. The mechanisms proposed include downregulation of pro-inflammatory cytokines, inhibition of lipid peroxidation, and enhancement of endogenous antioxidant defenses.

However, evidence is limited to animal models and in vitro assays; there is a lack of published human clinical trials as of mid-2024. There is also minimal reference to traditional use of P. fraternus specifically for colitis in ethnobotanical literature, though related species in the Phyllanthus genus have broader traditional applications for digestive and liver disorders. Therefore, while the use of P. fraternus in colitis is supported by preliminary scientific evidence, the quality and quantity of this evidence are modest, and clinical validation in humans is currently lacking.