Can kids be “too clean”? How often and how rigorously children should wash is not as clear-cut as you might think. If your tot’s face and hands are smeared with jelly or his hair is a tangled mass, a douse of warm water is a good idea—but beyond that, what is the right level of hygiene for kids?

One school of thought, called the “hygiene hypothesis,” suggests that a lack of early childhood exposure to infectious agents and microorganisms increases susceptibility to illness by changing how the immune system reacts to germs. This theory, first developed in the late 1980s, is not without detractors, but recent research, including a 2009 study conducted at the University of California, San Diego, suggests that America’s overly clean, “antibacterial” lifestyle may be weakening children’s defenses against allergens and inflammation. “Germs are not the enemy,” insists Lawrence B. Palevsky, MD, cofounder and president of the Holistic Pediatric Association. “Bacteria on skin play an important role in keeping us healthy.”

Although cleanliness is important for kids of all ages, Palevsky says there is no specific dictate for how often kids should bathe: “About one to three times a week for babies if and when they seem dirty is enough, and as they get older and out in the world it probably makes sense to bathe every day.” In addition to washing off grime, dust, and sweat—which can attract allergens and bacteria—taking baths is a valuable ritual and part of socialization. “Parents use bath time to wind down, relax, and bond with their small children, while kids learn responsibility and self-care as they get older,” says Palevsky.” Here are some basic guidelines for keeping kids clean and healthy.

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