The common cold is usually caused by a virus, and only a small percentage may be mixed with a bacterial infection, the latter often occurring a few days after getting sick; the flu is caused by the influenza virus. Antibiotics are used to fight against bacteria and are not effective against viruses, so misuse of antibiotics does not bring therapeutic effect when toxic side effects occur. In addition, the abuse of antibiotics can lead to the emergence of a large number of drug-resistant strains of bacteria. Experts suggest that, in general, you should not take antibiotics on your own unless you have a yellow pus nose with fever; when the flu symptoms are serious or complicated by other symptoms, you should consult a doctor promptly and choose antibiotics under the guidance of a doctor when there is a clear bacterial infection or complications.