Shampoos and Conditioners

Shampoo opens the hair cuticle to lift out oil and buildup. Conditioner closes it back down. They're designed to work in sequence. Skip conditioner and you're leaving the cuticle rough and open, which leads to frizz, breakage, and hair that's harder to manage. The best shampoo and conditioner routine is always both.

Use your hair's natural thickness as your guide: Fine for flat, greasy-by-noon hair. Medium for hair that's not especially thin or thick (the middle child of hair types). Thick for dense, coarser hair that needs serious moisture. OUAI makes it specific on purpose, because hair care for aging hair, curly hair, and fine hair all need something different. If you're still not sure, take our quiz.

As often as your hair needs it. Fine, oily hair usually needs washing every other day. Thick, curly, or very dry hair often thrives on once or twice a week. Over-washing strips natural oils and triggers more production, which makes the oiliness worse. 

Yes. You don't have to stick to pairs from the same line — mix based on what your hair actually needs. Some people love the Fine Hair Shampoo for volume but want a slightly richer conditioner. Some swap their regular conditioner for a Treatment Masque on wash days. 

Generally, no. The scalp produces its own oil, and applying conditioner there adds to it, making roots heavy and greasy faster. Mid-lengths to ends is where hair is typically drier and where conditioning does the most good. If your scalp itself is dry or irritated, the Scalp Serum is the right tool for that.

Moisturizing formulas focus on hydration: softness, manageability, shine. Repairing formulas go further by targeting damaged bonds and brittleness, not just surface dryness. Our Treatment Masques and Bond Repair Balm are in the repairing category. For hair that's damaged (heat, bleach, chemical processing), using both is a good idea.

Yes, significantly. Sulfate-heavy shampoos strip the oils and proteins that keep the cuticle smooth, and switching to sulfate-free shampoo is often the biggest single change for frizz. A good conditioner closes the cuticle and restores the moisture that keeps it flat. That alone handles a lot. For frizz that needs more than washing alone can fix, the Leave In Conditioner and Anti-Frizz Crème take it the rest of the OUAI.

No hard rule. It helps to stay within the same hair type so the formulas aren't pulling in different directions, but you don't need to be rigid. Many people do well with Fine or Medium Shampoo paired with a Treatment Masque instead of a standard conditioner on wash days. Find what makes your specific hair feel great and do that.