Poria mushroom (Poria cocos, also known as Fu Ling in Traditional Chinese Medicine) has been historically used in East Asian medicine for supporting kidney health, including conditions such as nephritis. In TCM theory, Poria is believed to strengthen the spleen, promote urination, and "drain dampness," which are traditional concepts often applied to disorders involving fluid retention or kidney dysfunction. It is a common component in classical TCM formulas prescribed for nephritis and related renal conditions, aiming to reduce edema and improve urinary function.

Modern scientific research on Poria’s effectiveness specifically for nephritis is limited and mostly preclinical. Some studies have identified anti-inflammatory, diuretic, and immunomodulatory effects of Poria extracts in animal models, which could be relevant to nephritis, but direct clinical evidence in humans is lacking or of low methodological quality. Thus, while its use is deeply rooted in traditional practices and is still common in herbal formulas in China and nearby countries, there is insufficient robust scientific validation to fully endorse its efficacy for nephritis by modern standards. The evidence rating of 2 reflects substantial traditional support and limited, preliminary scientific investigation, but not strong clinical proof.