Your Hand Sanitizer Isn't Killing Germs as Fast as You Think, Study Shows

You won't believe how long it takes for your hand sanitizer to work.

These days, enhanced hygiene is the new normal, and hand sanitizer is never far out of reach. And while there's no denying the convenience of a single-squirt solution to your hand contamination, one study says we tend to underestimate how long it takes for the product to do its job. As it turns out, you'll need to wait a full four minutes for alcohol-based sanitizers to eliminate viral particles, making regular hand washing seem a little more convenient after all.

The Japanese study, which was recently published in the journal mSphere, explains that hand sanitizers require four minutes of continuous rubbing to work properly. That's because viral particles are protected from the product's active ingredients by a thin layer of mucus, which takes time to break down.

As the study explains, this renders most hand sanitizing guidelines insufficient. "Current hand hygiene methods recommended by the CDC and WHO involve the use of disinfectants… for 15 to 30 seconds," the study reads. "However, our results suggest that this disinfection time is insufficient for the disinfection of infectious mucus." (Try saying that five times fast.)

The team also found that sanitizers present an additional challenge: the product doesn't work until mucus is completely dry, "because infectious mucus maintains a gel form." This means that for 30 minutes after your hands are contaminated, viral particles cannot be inactivated by sanitizer, and remain transmissible.

By contrast, traditional hand washing with soap and water can be done at any point after contamination, and takes just 30 seconds to work effectively. Soap quickly dissolves the lipid layer that protects viral particles and destroys the particles themselves, then washes away any leftover microorganisms as you rinse.

So, while you should probably still keep sanitizer handy for those instances where there's no sink in sight, soap and water should be your go-to solution whenever possible. When you do use sanitizer, you'll need to make sure you apply a generous amount of the product, and rub it in for the full four minutes. And for more on sanitizer safety, find out why The FDA Wants You to Stop Using These 60 Toxic Hand Sanitizers Right Now.

Lauren Gray
Lauren Gray is a New York-based writer, editor, and consultant. Read more