Is It Possible to Be Too Clean? A Doctor Weighs In on the Hygiene Hypothesis

We’re learning more every day about the benefits of being exposed to different kinds of bacteria, but it isn’t entirely clear whether excessive cleanliness can be harmful to adults. However, it does appear that oversterilizing our environment may be problematic for children’s health. A growing body of research has associated being exposed to germs and infections at an early age with a lower risk of developing asthma and allergies. (Experts have labeled this theory the “hygiene hypothesis.”)

Living on a farm, for example, or even having dogs in the house seems to reduce the risk of allergies in children. The thinking is that being around pathogens when you’re young, while your immune system is still developing, allows your immune system to fine-tune itself and learn to differentiate between harmful and harmless irritants. Without this learning, your immune system may overreact to harmless substances, like pollen.

That said, regular hygiene serves a purpose. You should still shower regularly, wash your hands before you eat—you know the drill. But there’s a decent case for a little more dirt and grime and a little less hand sanitizer and antibacterial wipes. We may wind up a healthier, less allergy-prone society down the road.

Health’s medical editor, Roshini Rajapaksa, MD, is assistant professor of medicine at the NYU School of Medicine.