Wellness & Education

Viruses vs. Bacteria: What’s the Difference?  

What do rabies, the Spanish flu, polio, Ebola, measles and smallpox all have in common? They are all caused by viruses.  

What do Bubonic Plague, leprosy, tetanus, botulism and syphilis all have in common? They are all caused by bacteria.  

What is a virus? What is a bacterium?  

Obviously, both bacteria and viruses can cause potentially deadly diseases. However, bacteria and viruses are two very different things.  A virus is a tiny package of genetic material that can only reproduce inside of a living host such as a plant, animal or bacterium. A bacterium is a small, single-celled organism that can reproduce by itself. A virus is not considered to be alive but a bacterium is a living thing.  


If you get sick with a virus your symptoms can be very similar to getting sick with a bacterial infection. You may have a sore throat, a cough, a fever, fatigue or vomiting and diarrhea. You may have pneumonia or meningitis. Only your healthcare provider can tell whether you have a virus or a bacterium, so only your provider can tell what you need to get better.  


It’s the “getting better” part of the story that really separates viral and bacterial illnesses. Both bacterial and viral infections can be deadly in some cases, but in general viral illnesses are harder to treat than bacterial illnesses. This is because most bacterial infections can be treated with antibiotics but there is no such “silver bullet” for viral infections.  

Every successful anti-viral medication has to attack the virus without attacking the host cells that it uses to reproduce. Antiviral medications are usually very specific and only work on a limited number of viruses. Whenever a new virus is discovered, a new medication usually has to be developed to treat it. In many cases, the best cure for a virus is to rest, treat the symptoms, and let the body heal itself. This takes time and it can be very uncomfortable for patients who are used to the relatively “quick fix” of many antibiotics. Fortunately, vaccines give healthcare providers the power to prevent some of the most serious and hard to treat viral diseases.   

Antiviral medications do not work against bacterial infections and antibiotics don’t work against viral medications. Using too many antibiotics can lead to new types of bacteria that are “resistant” or partially immune, to being controlled by antibiotics. This is one of the reasons that antibiotics should not be given unless they are clearly needed. Refused an Antibiotic? Here’s Why | Rush Memorial Hospital  

Same Symptoms, Different Causes and Solutions 

If you get an antibiotic for one sore throat and no antibiotic for the next one, it may not seem to make much sense. Having the same symptoms, however, doesn’t mean that the underlying causes are the same. When one sore throat is caused by a virus and one is caused by bacteria, the cures must be different as well. If you trust your healthcare provider to know what treatment to use when, you should have the best possible recovery. Unfortunately, when it comes to viral infections, that recovery may take longer than you’d like.