The 3 Bathroom Items You Should Never Share, According to Science

Imagine being away from home and realising you’ve forgotten the basics - a towel, a razor or a toothbrush.

Is it really a problem to borrow someone else’s?

It’s unlikely to cause harm every time, but it’s wise not to get into the habit of sharing used bathroom items.

Microbes can stay active for longer than you think

A wide range of disease-causing bacteria, viruses and fungi can live on everyday bathroom materials such as cloth, plastic and metal. These pathogenic microbes can remain viable on surfaces for surprisingly long periods - meaning they can still trigger infection days, months or even years after they were deposited.

To illustrate:

• The fungus Aspergillus can stay viable for over a month on cloth and plastic.
• Certain bacteria can persist on these types of surfaces for years.
• Many viruses remain viable for hours to months on materials including ceramics, metals, cloth and plastics.

That raises a practical question: what does this mean for borrowing a used towel, razor or toothbrush?

Researchers haven’t carried out randomised controlled trials (the gold-standard study design) to directly measure the risk - for instance, randomly allocating one group to shave their legs with somebody else’s used razor and comparing infection rates with a control group who didn’t.

Even without that kind of trial evidence, other studies provide useful clues.

Sharing towels, razors and toothbrushes: what the evidence suggests

Can I share towels? If you play footy, maybe not

Smaller, less rigorous studies point to a higher chance of developing a skin infection when people use towels that have already been used by someone else.

One report from the United States described an outbreak of antibiotic-resistant *Staphylococcus aureus* (often shortened to Staph) among a group of secondary-school American football players. Those who shared a towel were eight times more likely to develop an infection.

Staph can cause impetigo, a contagious skin infection. In rare instances, it can also progress to life-threatening complications such as septic shock and organ failure.

In that sporting outbreak, the likelihood of transmission was probably higher because contact sport often leads to small cuts and grazes - easy entry points for microbes.

A second US study tracked 150 households over 12 months, with each household having one child infected with Staph. When family members shared towels, the chance of Staph spreading within the home rose significantly.

It’s tempting to assume that showering washes microbes away. Soap and water do reduce microbial numbers on the skin, but they don’t remove them completely - and the typical bathroom’s warm, humid environment can support microbial growth.

Even without an obvious infection, becoming colonised by pathogens (carrying them without tissue damage or symptoms) can still be an issue. Colonisation may involve antibiotic-resistant organisms, increasing the chance of developing infections later that are more time-consuming and costly to treat.

How about a toothbrush? Think of the viruses

Hard objects can also harbour microbes, and toothbrushes are a particular concern because brushing can make gums bleed. For that reason, sharing a toothbrush is strongly discouraged: it can enable transmission of blood-borne viruses such as hepatitis C.

Not everyone in a higher-risk category for hepatitis C has been tested, and people can be infectious without any symptoms.

Items that come into contact with saliva - including toothbrushes - may also spread pathogens such as:

• herpes simplex virus type 1 (HSV-1), which causes cold sores
• Epstein–Barr virus, which causes glandular fever

Importantly, someone without visible cold sores can still shed HSV-1 and infect others.

One review found that toothbrushes were contaminated with potentially pathogenic bacteria including Staph, E. coli and Pseudomonas. It also detected HSV-1 in quantities sufficient to cause infection. HSV-1 can remain viable on plastic for two to six days.

Surely a razor’s OK? Not if you hate warts

Razors can also support viable microbes, and it’s difficult to shave without occasional nicks. That means sharing razors can create an opportunity for blood-borne virus transmission.

Razors, towels and other personal hygiene items may also spread human papillomaviruses that cause warts. It’s therefore not surprising that dermatologists advise each person to keep their own personal items.

Who’s most at risk?

If you have cuts or grazes, microbes have a clear route into the body, increasing the chance of infection - which helps explain the elevated risk seen in those footy (and contact-sport) settings where minor skin injuries are common.

Infection risk also rises when immune function is reduced. This is often the case for:

• babies, whose immune systems are still developing
• older people, whose immune function declines with age
• people taking immune-suppressing medicines, including cancer drugs, oral corticosteroids and medications used after an organ transplant
• people with type 2 diabetes, because higher blood glucose levels impair immune cells and related molecules

That said, the overall likelihood of catching an infection from a single episode of sharing is generally low. And if you share a towel, razor or toothbrush with a partner, you’re likely to be in close contact frequently and will be swapping microbes in other ways anyway.

Practical ways to reduce risk when you’re travelling

If you’re caught short while staying with friends, family or in shared accommodation, the safest approach is to avoid sharing used bathroom items and instead keep a small backup kit. A spare toothbrush, a travel-sized toothpaste and a disposable razor are lightweight, inexpensive, and can prevent awkward compromises.

If sharing can’t be avoided, it helps to reduce opportunities for microbes to persist: allow towels to dry fully between uses, avoid leaving them bunched up in damp bathrooms, and keep personal items (especially toothbrushes) separate so they don’t touch.

Even so, it remains sensible to avoid making a routine of borrowing other people’s used towels, razors and toothbrushes.

Thea van de Mortel, Professor Emerita, Nursing, School of Nursing and Midwifery, Griffith University

This article is republished from The Conversation under a Creative Commons licence. Read the original article.