Skip to Content

Published on April 17, 2017

Viral Versus Bacterial – What’s the Difference?

Woman sick with tissues and thermometerWe hear the terms “viral” and “bacterial” all the time, but what is the difference and how does it change the treatment of an illness?

As you might have guessed, a bacterial infection is caused by bacteria, and a viral infection is caused by viruses. Both are a type of microbe, which can be spread by coughing; sneezing; contact with another infected person, animal or insect; or contact with a contaminated surface.

Both viral and bacterial infections can cause mild, moderate or severe illnesses or diseases. For example, smallpox is caused by a virus and meningitis is caused by bacteria.

Many bacteria are harmless and our body is full of different types of them. They help digest our food, provide nutrients and much more. Fewer than one percent of bacteria actually cause disease.

Viruses, however, usually do cause disease and are pretty particular about which cells they attack. Their structure makes them more resistant to treatment, too.

It can be difficult to diagnose an illness because many symptoms can be caused by either a virus or bacteria. This is why your doctor will physically examine you and may order blood, urine or culture (tissue) tests.

There are a few tips and tricks for determining the difference yourself. For example, a sore throat could be either, but if there are white spots at the back of your throat, it may point to bacteria. Fevers also tend to be higher and last longer with a bacterial infection.

The only way to know for sure is to see a doctor for testing. Viruses do not respond to antibiotics, so understand that you may not always leave with a prescription. Sometimes, the best approach really is rest, fluids and some pain medication if appropriate.

Call your primary care provider for an appointment, or try MercyCare’s new service, eArrival, to pick your arrival time at any MercyCare Urgent Care.

Section Links

Health Education

Login to MyChart
Find A Doc