Shampooing every day isn’t only wasteful, it can also harm your hair, according to NPR. Back in the olden days, when waterfalls passed for high-pressure showers, people would shampoo only once a month. That wasn’t enough, but if you shampoo more than three times a week, you’re actually making your hair oilier because your glands need to work overtime to replace the natural oils you’re washing away.
“If you wash your hair every day, you’re removing the sebum,” explains Michelle Hanjani, a dermatologist at Columbia University. “Then the oil glands compensate by producing more oil,” she says.
She recommends that patients wash their hair no more than two or three times a week.
There’s also a lot of variation among hair types. African-Americans and people with curly hair can go even longer between washes compared to folks with straight hair.
Of course, you shouldn’t misread this as an invitation to shop showering. That’s still good and healthy. Just cut back on the shampoo.