Pseudostellaria, particularly Pseudostellaria heterophylla (commonly known as "tai zi shen"), has a long history of use in Traditional Chinese Medicine (TCM) as a tonic herb. In TCM, it is thought to nourish yin and generate body fluids, which is interpreted as supporting the health and function of mucus membranes, particularly in the respiratory and digestive systems. It has been traditionally used for symptoms such as dry cough, dry mouth, and general weakness, which are believed to be linked to dryness or deficiency of bodily fluids.

Scientific evidence supporting these uses is limited. A small number of pharmacological studies have identified polysaccharides and saponins in Pseudostellaria that may have immunomodulatory and anti-inflammatory effects, and some animal studies suggest potential benefits for the respiratory tract. However, these studies are preliminary, often use isolated compounds at high doses, and do not directly demonstrate effects on mucus membranes in humans. There is currently a lack of high-quality clinical trials validating its use for supporting mucus membranes or treating related conditions.

In summary, the use of Pseudostellaria to support the mucus membranes is primarily justified by traditional use in TCM rather than robust scientific validation.