Platycodon grandiflorus (commonly known as balloon flower or Jie Geng in traditional Chinese medicine) has a long history of use in East Asian herbal medicine for treating respiratory ailments, including dry cough. Traditional Chinese medicine (TCM) texts describe Platycodon root as an agent that "opens up the lungs," "expels phlegm," and "relieves sore throat," often in combination with other herbs. It is commonly included in formulations targeting coughs, especially those characterized as "dry" or "non-productive" in TCM terminology.

Modern pharmacological studies have identified several bioactive compounds in Platycodon, such as saponins (notably platycodin D), which exhibit anti-inflammatory, expectorant, and antitussive (cough-suppressing) effects in animal models. However, most clinical evidence in humans is limited or of low quality, and well-designed randomized controlled trials specifically evaluating its efficacy for dry cough are lacking. Thus, while the traditional use is well-established and some preclinical research provides plausible mechanisms, robust scientific confirmation in human populations remains insufficient.

In summary, Platycodon's use for dry cough is justified primarily by traditional use and supported by some promising but preliminary scientific findings, meriting a moderate evidence rating.