Traditional Chinese Medicine for the Common Cold: Evidence and Potential Mechanisms.

Traditional Chinese medicine (TCM) has a history of over 2000 years in treating infectious diseases, among which the clinical treatment of the common cold (colds) and influenza (flu) is the most widespread and well-established. It is difficult to tell the difference between a cold and the flu based on the symptoms alone. The flu vaccine protects against influenza, but there is no vaccine or specific medication to protect against the common cold. Due to the lack of a reliable scientific basis, TCM has not received sufficient attention in Western medicine. Therefore, we systematically evaluated the scientific evidence proving the efficacy of TCM intervention in treating colds for the first time by examining theoretical principles, clinical research, and pharmacological perspectives, as well as the mechanisms behind this efficacy. In TCM theory, there are four important external environmental factors that may cause a cold, which are called "cold, heat, dryness, and dampness". The scientific basis for this theory has been described and will help researchers to understand and recognize its importance. The results of the systematic review of high-quality randomized controlled clinical trials (RCTs) have shown that TCM is effective and safe for the treatment of colds. Therefore, TCM might be used as a complementary or alternative approach to cold treatment and management. Some clinical trials have demonstrated that TCM may have potential therapeutic effects in preventing colds and treating their sequelae. However, more high-quality, large-scale randomized controlled trials should be conducted in the future for further verification. Pharmacological studies have shown that active ingredients extracted from TCM for treating colds have antiviral, anti-inflammatory, immune-regulating, and anti-oxidative properties. We expect that this review will guide the optimization and rationalization of TCM clinical practice and scientific research in the treatment of colds.