You never know where bills and coins have been, or what kind of germs money is carrying. As it turns out, anything from benign bacteria to dangerous superbugs could be catching a ride on your currency.

Here’s what you need to know about the germs on money and what you can do to protect yourself.

Money can spread germs from person to person

Money can carry viruses, protozoa, and bacteria. Depending on where it’s been, it could carry almost anything. One old and widely-cited study even found that 79% of one-dollar bills contain traces of cocaine.

Another study of dollar bills in New York City found a whole host of active microbes, the most common of which was propionibacterium acnes, the bacteria responsible for acne breakouts. The researchers analyzed a set of one dollar bills obtained from a Manhattan bank and found that both sets were teeming with bacteria.

"Money serves as a fomite, an inanimate vehicle by which pathogens can be spread," says Charles Bailey, MD, medical director for infection prevention at Providence St. Joseph Health.

For example, if you touch the money, then touch someone else's hand, you can spread the germs to them. Or if you touch dirty money and then touch a door knob, elevator button, or the touchscreen at the ATM, you could also spread infection.

Both bills and coins can hang onto those germs, giving them a chance to spread via the hand of anyone who handles them, according to Richard Honaker, MD, a family medicine physician in Virginia and chief medical advisor at Your Doctors Online. One study found that methicillin-resistant S. aureus (MRSA), a superbug that has developed a resistance to penicillin, can easily survive on coins.

And that's how easy it can be for someone infected with a virus to spread that virus to you. It just takes a touch. One study found that physical currency changes hands at least 55 times a year, or almost once a week. But many people don't realize it or overlook the risk.

Though how long germs live on surfaces is specific to the pathogen, some viruses can live for up to 72 hours, which is why it is important to be careful when handling money.

How to avoid germs transferred by paper money

If you're concerned about paper money harboring germs, you can try to clean your money. But it might not be easy.

"Attempting to clean the money is potentially feasible but much more complicated than handwashing-and involves handling the money more than might otherwise be the case," said Bailey.

You could simply try to protect yourself from the germs that might be hiding out on your cash.

  • Wash your hands with soap or hand sanitizer after touching any coins or bills.
  • Wear gloves. A pair of disposable sanitary gloves can protect your hands from the germs on the money you're handling.

There is no perfect or easy way to clean money at home. China, amidst the coronavirus pandemic, has started large operations involving disinfecting money with UV light and high temperatures before releasing bills back into circulation.

There are imperfect options for home sanitation like putting bills through the laundry or brushing each bill with disinfectant. But the World Health Organization (WHO) has said that the best solution to deal with potentially contaminated money is to simply wash your hands thoroughly after touching any bills or coins.

Related stories about sanitation and keeping clean: