Platycodon grandiflorus, commonly known as balloon flower, is a traditional herbal remedy widely used in East Asian medicine, particularly in China, Korea, and Japan. In traditional Chinese medicine (TCM), the root of Platycodon (called Jie Geng) is prescribed for ailments affecting the throat and respiratory system, including laryngitis, sore throat, cough, and phlegm-related conditions. The rationale in TCM is that Platycodon helps to "open up the lung qi," expel phlegm, and relieve throat discomfort.

Scientific studies on Platycodon grandiflorus have identified anti-inflammatory, expectorant, and antimicrobial properties in vitro and in animal models. Some research indicates that saponins in Platycodon root may help reduce airway inflammation and inhibit certain pathogens. However, clinical trials specifically evaluating its efficacy for laryngitis in humans are lacking or of low quality. Most of the support for its use in laryngitis comes from its inclusion in classical and modern herbal formulas for sore throat and hoarseness in TCM literature.

In summary, Platycodon's use for laryngitis is primarily based on traditional practice, supported by some pharmacological findings but without robust clinical evidence for this specific condition. Thus, the evidence rating for its use in laryngitis is modest.