Germs are living things that can be found everywhere, from the air to the ground to your body. The main types of germs are bacteria, viruses, fungi and protozoa. Some germs are good for you and keep you healthy. Other germs can cause harm and even be dangerous. You can prevent the spread of germs by washing your hands.

What are germs?

Germs are microorganisms, or microbes, that can cause disease. They’re living things that you can find all around you. Germs are in the air, water and soil. They’re on plants, animals and food. Germs are on the surfaces and objects you touch. They’re also in your body and on your skin.

Germs are a part of everyday life. Some germs are harmless and even helpful. You need them to keep you healthy. But other germs can be harmful. When those germs spread to you, they can make you sick. You can prevent the spread of germs that lead to illness by washing your hands.


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What are the different types of germs?

The four main types of germs are bacteria, viruses, fungi and protozoa.


Bacteria are tiny, one-celled organisms that get their nutrients from their environment. Some bacteria are good for you. They keep your digestive system functioning properly and they prevent harmful bacteria from getting in.

Other bacteria give off toxins that can cause illness or infection. These include cavities, urinary tract infections and strep throat. Healthcare providers may use antibiotics to treat bacterial infections.


Viruses aren’t complete cells — they’re genetic material packaged inside a protein capsule. Viruses can’t survive without living cells. They need a host with living cells to reproduce. If they find a host (such as your body), they can spread easily and make you sick.

Some viruses cause minor illnesses such as the common cold or the flu. Other viruses cause serious diseases such as measles and HIV/AIDS. Antibiotics aren’t effective against viruses. Healthcare providers can treat a few viral infections with antiviral medication.


Fungi (pronounced FUN-guy) are plant-like organisms that have more than one cell. A fungus gets its nutrients from animals and plants like bacteria. They grow and thrive in warm, damp environments. Examples of fungi include mold, mildew, mushrooms and yeasts.

Most fungal infections aren’t dangerous to otherwise healthy people. Common fungal infections include yeast infections and athlete’s foot. Healthcare providers may treat fungal infections with antifungal medication.


Protozoa (pronounced pro-toe-ZO-uh) are one-celled organisms like bacteria. However, they contain a nucleus, which makes them more like animal and plant cells. Protozoa like moisture, so they often spread disease through contaminated water.

Some protozoa are parasites. Parasites need to live on a plant or animal to survive. Malaria and toxoplasmosis are examples of parasitic infections. Healthcare providers may treat parasitic infections with antiparasitic medication.

When were germs discovered?

The history of germs goes back centuries. A Dutch scientist named Antonie van Leeuwenhoek first discovered bacteria using an early microscope in 1676. Through the progression of microbiology, many further discoveries were made over the years.

In 1857, French chemist Louis Pasteur proved that food spoiled because of contamination by microorganisms. This led to his germ theory of disease, which states that germs known as pathogens can lead to infection and disease. Before this discovery, scientists believed in the theory of spontaneous generation. They thought living things developed from nonliving matter.


What do germs look like?

You can’t see most germs with the naked eye — they’re too small. If you were to look at germs under a microscope, you would see tiny balls, rods or spirals. They’re so small that 1,000 germs could line up across the top of a pencil eraser.

How do germs spread?

Germs spread in many different ways. They can spread through:

  • Touching or having close contact with someone who has the germ. This may include hugging, kissing or sharing utensils.
  • Breathing in (inhaling) air after someone with the germ sneezes or coughs.
  • Touching the poop of someone who has the germ. This may be through changing your baby’s diaper, then touching your nose, mouth or eyes.
  • Touching surfaces and objects that have the germ on them and then touching your nose, mouth or eyes.

Germs may also spread from:

  • Parent to baby during pregnancy or childbirth.
  • Animal and insect bites.
  • Contaminated soil, plants, food or water.


How long do germs live on surfaces?

Germs can live on surfaces from minutes to months, depending on several factors. These factors include:

  • Germ: What type of germ — which bacterium, virus, fungus or protozoan?
  • Amount: How much of the germ remains on the surface?
  • Surface: What type of surface — soft (porous) or hard (nonporous)?
  • Environment: What’s the temperature and humidity in the area?

Viruses typically live longer on stainless steel, plastic and other nonporous surfaces than on fabric, tissue and other porous surfaces.

Cold germs can live on surfaces for up to one week, but they lose effectiveness after the first 24 hours. Cold germs on your hands can live for up to one hour. The influenza (flu) virus can live for up to 24 to 48 hours on hard surfaces. The coronavirus can live from a few hours to a few days.

Bacteria such as E. coli and salmonella may only live for 20 minutes but can live for up to four hours on hard surfaces. Clostridium difficile (C. diff) can last for up to five months on hard surfaces.

Does hydrogen peroxide kill germs?

According to the Centers for Disease Control and Prevention (CDC), you can use hydrogen peroxide to kill a wide variety of germs, including bacteria and viruses, on nonporous surfaces. For best results, spray the surface with hydrogen peroxide and let it stand for at least one minute before wiping it off.

What kills germs?

Many common methods kill germs, but some don’t.

Does rubbing alcohol kill germs?

Rubbing alcohol, including hand sanitizer, can kill germs as long as it contains at least 70% isopropyl alcohol. For best results, spray or wipe the surface with rubbing alcohol and let it stand for at least 30 seconds before wiping it off.

Does vinegar kill germs?

No. According to the CDC, vinegar and vinegar-based products are ineffective against most bacteria and viruses, including the influenza virus and coronavirus. Undiluted white vinegar may work on some types of bacteria, but it’s not the most effective way to kill germs.

Does heat kill germs?

According to World Health Organization, temperatures of at least 140 degrees Fahrenheit (60 degrees Celsius) are enough to kill most viruses. Boiling water can kill off the bacteria on food and running your dishwasher is enough to sterilize your dishes from germs.

Does hot water kill germs?

According to the U.S. Department of Agriculture, hot water can kill germs, but the level of destruction depends on several factors. These include:

  • The heat resistance of the germ.
  • Amount of time the germ is exposed to hot water.
  • The temperature of the water.
  • Food and plant particles that are present.

How can I prevent the spread of germs?

There are many ways you can prevent the spread of germs. The best thing you can do is wash your hands regularly with soap and water for at least 20 seconds. Even though high temperatures kill most germs, washing your hands in cold water is fine. That’s because the water helps get rid of excess dirt, but it doesn’t get hot enough to kill the germs when you’re washing your hands.

Other ways to prevent the spread of germs include:

  • Carrying hand sanitizer that contains at least 70% isopropyl alcohol. This works in a pinch if you can’t access soap and water to wash your hands.
  • Sneezing or coughing into your elbow or covering your nose or mouth with a tissue.
  • Staying home if you’re sick.
  • Avoiding people who are sick.
  • Practicing good food handling when cooking and storing food.
  • Frequently cleaning and disinfecting surfaces and objects that are touched often.

A note from Cleveland Clinic

Germs are everywhere. They’re a part of life. Some germs, such as the bacteria in your gut, are actually good for you and keep you healthy. But other germs can cause harm and even be dangerous. There are many ways to prevent the spread of germs. The best way is by simply washing your hands with soap and water. If you aren’t near water, hand sanitizer is a great backup.

Medically Reviewed

Last reviewed on 11/28/2022.

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