Andrographolide, the major bioactive compound of Andrographis paniculata, is widely used in traditional medicine, especially in Asia, for the prevention and treatment of common colds. Scientific evidence supports its use to some extent: several randomized controlled trials and meta-analyses have evaluated standardized extracts of Andrographis paniculata (often containing known amounts of andrographolide) for upper respiratory tract infections, including colds. A 2017 meta-analysis published in PLOS ONE found that Andrographis extracts significantly reduced the duration and severity of cold symptoms in comparison to placebo, with a good safety profile. The proposed mechanisms include immunomodulatory, anti-inflammatory, and antiviral effects, all of which may contribute to reduced symptom severity and duration.

However, most studies have focused on treatment rather than prevention, and sample sizes are often small, with some risk of bias. The quality of evidence is moderate, and guidelines vary in their recommendations. While there is a long tradition of use and some scientific validation for the treatment of colds, evidence for prevention is less robust but still exists. Thus, the use of andrographolide for cold prevention is supported by moderate scientific evidence, but more high-quality research is needed to establish efficacy and optimal dosing for preventive use.