What is the difference between bacterial and viral infections?

A bacterial infection is an infection that's caused by bacteria.

Bacteria are single cell organisms. They are so small that you can't see them without magnification.

Your body is full of bacteria. In fact, it's thought that your body has more bacteria than human cells. Most bacteria are harmless, and some are even helpful. The bacteria in your gut helps you to digest food.

Some examples of bacterial infections are:

• group A streptococcus (GAS) infections
• meningococcal disease
• Q fever
• tuberculosis
• urinary tract infection (UTI)
• whooping cough

Like bacteria, viruses can cause infections.

Viruses are very small and live inside host cells. Viruses cause infections when they multiply inside your cells.

Viruses can be spread to other people by:

• tiny droplets from your nose or mouth
• vomit
• faeces (poo)

Some examples of viral infections are:

• chickenpox
• COVID-19
• hand foot and mouth disease
• influenza (flu)
• measles
• mpox (monkeypox)

It can sometimes be difficult to know what is causing an infection. This is because viral and bacterial infections can cause similar symptoms.

To see what sort of infection you have, your doctor will ask you about your symptoms. They may also examine you and may organise tests of your:

• blood
• urine (wee)
• stool (poo)
• swab from your nose or throat

It's important to know if your infection is caused by bacteria or viruses. This is because the treatments differ.

Treating a bacterial infection

Doctors usually treat bacterial infections with antibiotics. It's important to use the right antibiotic for each type of bacterial infection. The right antibiotic will kill the bacteria or stop processes that they need to live and grow.

Antibiotic resistance is a growing problem in the world. It's important that you take antibiotics exactly as your doctor or pharmacist tells you.

Your doctor will only prescribe antibiotics when they think the treatment will be of help.

Many diseases that are caused by bacteria or viruses can be prevented by vaccination. These are known as vaccine-preventable diseases.

Many of these vaccinations are free through the National Immunisation Program Schedule (Opens in new tab).

Good hygiene practices can help to lower your chances of getting sick from bacteria or viruses. Good hygiene practices can also help lower your chance of spreading infections. You should:

• wash your hands often
• not share cups, drink bottles or cutlery
• cough or sneeze into your elbow
• use tissues and throw them in a bin as soon as you have used them

Learn which diseases are notifiable in Australia (Opens in new tab), on the Australian Centre for Disease Control (CDC) website.

If you are worried that you have an infection, you can call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.

Other languages

Health Translations has information on antibiotic resistance in languages other than English (Opens in new tab).