Ingredient dictionary

Serine

Also listed as: L-Serine

Serine is an amino acid, a small building block of proteins, that helps attract and hold water in a formula. It is on the label of 28 products in our library. Checked against our library November 6, 2026.

The catch: none for most people; check the full product list if your skin reacts easily.

What Serine does

Helps skin hold on to moisture
Attracts water into the formula
Helps conditioners feel smooth

Serine is one of the amino acids that build proteins in the body. It also appears in the skin's natural moisturizing factor, a mix of water-loving molecules in the outer layer of skin. Because of that, cosmetic chemists see it as a familiar, gentle choice for hydration.

In a formula, serine works as a humectant, which means it draws water toward the skin or hair and helps keep it there. It dissolves easily in water, so it blends into lotions, cleansers and conditioners without much effort. Products with serine usually feel light and smooth rather than greasy.

Good for

Suits people who want gentle, everyday hydration in moisturizers, cleansers, and leave-in hair products.

Be careful if

Nothing in particular for most skin types.

Frequently asked questions

Is serine safe for sensitive skin?

Serine is a natural amino acid that the skin already contains, so it is generally well tolerated. As with any product, a patch test on a small area is a sensible first step if your skin reacts easily.

Does serine help hair?

In hair products, serine is used as a conditioning ingredient. It helps conditioners and leave-in products feel softer and easier to comb. It works best as one part of a formula, so the rest of the product also matters.