This Is the One Time You Should Never Mismatch Your Shampoo and Conditioner

Anyone who’s ever studied the back of their shampoo already knows what every bottle says: “This product works best with insert same-brand conditioning product here.”

And if you’ve ever wondered if it’s a serious suggestion—that somehow the ingredients in one brand of shampoo could have a catastrophic reaction with the ingredients in a different brand’s conditioner—most stylists say ‘no.’

“[Brands] sell matching products because, well, they want to sell more product. By recommending that they work well together, they’re able to sell an entire line. A lot of it is marketing,” Susan Raffy, a cosmetic chemist and president of Susan Raffy Consulting, told Refinery 29. “The only way that brands could substantiate claims [that their products work better together] is if they tested their formulas against other brands. That’s expensive. It rarely happens.”

In fact, most stylists recommend choosing a shampoo that addresses your hair’s needs as they are from the scalp to mid-length and a conditioner that suits it from mid-length to your ends. That means if you’ve got flat hair with dry ends, choose a volumizing shampoo and a hydrating conditioner.

So what’s the outlier to this rule? Hair you’re treating for dandruff or itchiness. One Proctor and Gamble study found that pyrithione zinc, the active ingredient in Head & Shoulders cleanser, is decreased by 60 percent if users don’t follow up with the brand’s matching conditioner.  This is how to find the best shampoo for your hair type.

Moral of the story: Mix away, as long as you’re not treating your scalp for dandruff.