Radix Isatidis has the effect of clearing away heat and toxic materials, and can be used to improve the symptoms of patients with wind-heat cold, but Radix Isatidis cannot prevent colds. Colds are all caused by bacterial infection or viral infection. Banlangen has neither bactericidal nor antiviral effects, so it can't prevent colds. If you want to prevent colds, you should pay attention to avoiding them, don't be greedy for cold, drink more hot water, have more rest, pay attention to personal prevention when colds are prevalent, and develop good eating habits and daily life. Once you have cold symptoms, you should use anti-cold drugs for treatment in time. If it is a wind-heat cold, you can use Banlangen to improve the symptoms for treatment.