A bitter herb, Andrographis paniculata, used in traditional Ayurvedic and Chinese medicine and marketed in the West as an immune-supporting remedy for colds and flu. Its leaves contain andrographolide and related diterpenoids credited with anti-inflammatory and antimicrobial activity in laboratory studies. Clinical trials suggest it may modestly reduce the severity and duration of upper respiratory symptoms, though the evidence is less robust than for conventional treatments and product quality varies widely. It is intensely bitter, traditionally considered part of its medicinal virtue, and is sold as capsules, tablets, and tinctures. Safety is generally good for short-term use, but it can cause allergic reactions and is not recommended in pregnancy. As with many traditional herbs, enthusiastic marketing outpaces the evidence base.