Andrographis paniculata, commonly known as "king of bitters," is a medicinal herb traditionally used in Ayurvedic and Chinese medicine for respiratory infections. Its primary bioactive compound, andrographolide, has demonstrated anti-inflammatory, immunomodulatory, and some antiviral properties in laboratory studies.

Modern clinical research on Andrographis has mostly focused on upper respiratory tract infections (URTIs), such as the common cold and pharyngotonsillitis. Several randomized controlled trials and meta-analyses suggest Andrographis may reduce symptom severity and duration in uncomplicated URTIs, particularly when used early in the illness. However, evidence regarding its efficacy for pneumonia specifically—especially moderate to severe, or hospital-acquired pneumonia—is limited and of low quality.

Some small studies and animal research indicate that Andrographis may have immune-boosting and antimicrobial effects that could, in theory, be beneficial in pneumonia. However, large-scale, high-quality clinical trials in humans with pneumonia are lacking. Mainstream medical guidelines do not recommend Andrographis as a standard treatment for pneumonia, and it should not be used as a substitute for antibiotics or professional medical care in this serious condition.

In summary, while there is some scientific interest in Andrographis for respiratory infections, evidence specifically supporting its use in pneumonia is limited and not robust. Its use is primarily supported by tradition and extrapolated from studies on milder respiratory illnesses.