Answer: Antibiotics are totally worthless and ineffective for the treatment of flu or other viral diseases.
Viruses pose a considerable challenge to the body’s immune system because they hide inside cells. This makes it difficult for antibodies to reach them. However, special immune system cells, called T-lymphocytes, can recognise and kill cells containing viruses, since the surface of infected cells is changed when the virus begins to multiply. Many viruses, when released from infected cells, will be effectively knocked out by antibodies, produced in response to infection or previous immunisation.
Antibiotics kill bacteria by interfering with their metabolic processes, but viruses are so simple they use their host cells to perform their activities for them. This is why antibiotics are useless against viral infections. Antiviral drugs work by interfering with the viral enzymes. Antiviral drugs are currently only effective against a few viral diseases, such as influenza, herpes, hepatitis B and C and HIV, but research is ongoing. A naturally occurring protein, called interferon (which the body produces to help fight viral infections), can now be produced in the laboratory and is used to treat hepatitis C infections.
Viral diseases should never be treated with antibiotics. Sometimes a person with a viral disease will develop a bacterial disease as a complication of the initial viral disease. For example, children with chickenpox often scratch the skin sores caused by the viral infection. Bacteria such as staph can enter those lesions and cause a bacterial infection. The doctor may then prescribe an antibiotic to destroy the bacteria. The antibiotic, however, will not work on the chickenpox virus. It will work only against staph.
Antibiotics do not affect viruses, but many flu deaths are due to secondary bacterial infections such as pneumonia. Antibiotics would be used to treat these cases.