Shi Wei (Pyrrosia leaf) is a fern leaf used in Chinese medicine primarily for urinary problems such as painful urination, urinary stones, and blood in the urine. It clears heat from both the Urinary Bladder and the Lungs, so it is also used for coughs and bronchitis. Additionally, it helps stop bleeding caused by excess internal heat.

'Promotes urination and treats painful urinary dysfunction' (利尿通淋 lì niào tōng lín) is Shi Wei's primary action. In TCM, 'lin syndrome' covers a range of urinary problems including painful, burning, or difficult urination, often with urgency or the passage of sediment. Shi Wei's bitter and sweet taste combined with its cool nature allows it to clear heat and dampness from the Urinary Bladder, restoring normal water flow. This makes it especially useful for hot, painful, bloody, or stone-type urinary complaints. Classical sources such as the Shen Nong Ben Cao Jing record that it 'treats the five types of urinary blockage and promotes the water passages.'

'Clears Lung Heat and stops coughing' (清肺止咳 qīng fèi zhǐ ké) refers to Shi Wei's ability to enter the Lung channel and cool excess heat there. When the Lungs are overheated, a person may experience coughing, wheezing, or thick phlegm. Shi Wei's cool, bitter nature descends and clears this heat, helping to calm coughs. It has been used in modern clinical practice for both acute and chronic bronchitis.

'Cools the Blood and stops bleeding' (凉血止血 liáng xuè zhǐ xuè) means Shi Wei helps control bleeding that arises from heat driving the blood recklessly out of the vessels. This includes blood in the urine, nosebleeds, coughing up blood, and heavy or prolonged menstrual bleeding. Because it both cools heat and stops bleeding, it is particularly well suited for bleeding conditions where heat is the underlying driver.