Why aren't antibiotics such as penicillin or vancomycin against viruses?

Answer 1

Antibiotics, also known as antibacterial drugs, is the term used to classify the large assortment of available medications that kill bacteria. These medications specifically target bacteria by chemically interfering with its normal structure and function. To understand why antibiotics are not effective against viruses, it is best to understand the differences between bacteria and viruses:

Bacteria are single-celled organisms that take in food, use energy, grow, reproduce, and respond and adapt to their environment. When inside a host, the bacteria can only survive if these characteristics of life are met. For a bacterial infection to persist, the bacteria must be able to grow and reproduce by adapting to the immune system's response to it. Antibiotics work by causing a change in conditions that the bacteria cannot adapt to, killing the bacteria and clearing up the infection.

Viruses are much smaller than bacteria, and commonly consist of DNA or RNA and a protein shell for protection. Viruses do not take in food, grow, or reproduce on their own; they inject their DNA or RNA into a cell, causing that cell to constantly produce more viruses. There are very few metabolic processes in the virus that medications can interfere with. Viral infections take place by altering the functions of the host's cells. Therefore, it is more difficult to prevent the reproduction of viruses without destroying healthy cells.

Antiviral medications can be prescribed to treat diseases caused by viruses. However, most viral infections are naturally cured by the host's immune system. Antiviral medications boost the immune system, or allow more favorable conditions for the immune system to function.

Antibiotics are easier to produce because bacteria are larger and have more metabolic (chemical) pathways that can be interrupted by medication without damaging healthy cells within the host. These medications are specific to bacteria, and generally have no impact on viral infections.

It is important to note that using antibiotics to treat viral infections is dangerous because prolonged or unnecessary use of antibiotics can lead to antibiotic-resistant bacteria, complicating the recovery process for a future bacterial infection.

Answer 2

Antibiotics are much different than antivirals, and they cannot be used in place of the other. Bacteria and viruses are completely different "organisms". They do not look or act the same. Antibiotics cannot treat viruses because viruses are nothing like bacteria.

For example, some antibiotics kill bacteria by keeping he bacteria from reproducing. Viruses, on the other hand, can't reproduce by themselves. They need to infect bacteria or other types of cells, where they can reprogram the cell to create copies of the virus. How would an antibiotic which keeps bacteria from growing possibly inhibit the growth of viruses which do not reproduce in the same way? Answer: they can't.

Antiviral medications treat viral infections. In the same way that antibacterials cannot be used to treat viral infections, antiviral medications cannot be used to treat bacterial infections.