Polyquaternium-37

Polyquaternium-37 is a synthetic cationic polymer, meaning it’s a large, positively charged ingredient made of repeating units. In skincare and haircare, that charge helps it bind to the negatively charged surface of skin and hair, where it can form a light film. This film gives products a smoother feel, helps them spread more evenly, and can improve the way a formula clings or stays in place. It also works as a conditioning and thickening agent, helping textures feel richer and more cushiony.

For skin, Polyquaternium-37 can make lotions, creams, and cleansers feel more elegant and less watery, while leaving a soft, silky finish. For hair, it can help reduce roughness, improve slip, and make detangling easier, which is especially useful in conditioners, leave-ins, and styling products. People with dry, frizzy, or easily tangled hair may notice the most benefit. One caveat: because it forms a film, very fine hair or skin that dislikes heavy-feeling products may prefer lighter formulas, and buildup can happen if it’s used often in layered routines.