Phyllanthus fraternus, closely related to Phyllanthus niruri, has been used in traditional systems of medicine, such as Ayurveda and folk medicine, primarily for its antimicrobial, hepatoprotective, and anti-inflammatory properties. Its use for treating or supporting recovery from infections is primarily rooted in these traditional practices. A variety of Phyllanthus species have been used for centuries in India and other regions to address a range of ailments, including infections of the urinary tract, liver, and skin. The traditional rationale is based on the plant's perceived ability to "cleanse" the system and reduce inflammation.

Scientific studies specifically on Phyllanthus fraternus are limited; most research focuses on related species like P. niruri. Some in vitro and animal studies using extracts of P. fraternus have indicated antimicrobial activity against certain bacteria and fungi, but this evidence is preliminary and not yet supported by robust clinical trials. The active compounds, such as lignans, flavonoids, and tannins, are believed to contribute to these effects, but the precise mechanisms and efficacy in humans remain unclear.

In summary, the use of Phyllanthus fraternus for infection is primarily justified by tradition, with some low-level scientific support, but stronger clinical evidence is lacking. Its rating for evidence is therefore a 2 out of 5.