Hedyotis diffusa (also known as Oldenlandia diffusa) is an herb widely used in Traditional Chinese Medicine (TCM) for the treatment of various inflammatory and infectious diseases, including hepatitis. Its use for hepatitis is primarily justified by tradition, with classic TCM texts and folk practice prescribing it to "clear heat and detoxify," which in TCM theory is associated with the treatment of liver disorders.

There are some preclinical studies indicating that extracts of Hedyotis diffusa may have hepatoprotective and anti-inflammatory effects in animal models, such as reducing markers of liver injury or inflammation in chemically-induced hepatitis in mice. However, these studies are limited in number, often use crude extracts, and lack rigorous controls. There are no robust clinical trials in humans that specifically evaluate the efficacy of Hedyotis diffusa for hepatitis, and the mechanisms of action remain unclear.

Therefore, while Hedyotis diffusa is traditionally used for hepatitis and early laboratory research offers some biological plausibility, strong scientific validation is lacking. Its continued use is primarily based on traditional practice rather than high-quality clinical evidence.