---
title: "Hyaluronic Acid — Glossary | School of Dermatology"
url: https://schoolofdermatology.com/glossary/hyaluronic-acid
description: "Understand hyaluronic acid, how it holds 1,000x its weight in water, its role in skin hydration, and how to use it effectively in your routine."
lang: en
---

Glossary

# Hyaluronic Acid

hy-al-yoo-RON-ik AS-id

## Definition

Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan found throughout the body's connective tissues, with the highest concentrations in the skin, eyes, and joints. It is renowned for its extraordinary ability to hold up to 1,000 times its weight in water, making it one of the most effective hydrating ingredients in skincare. In the skin, HA helps maintain volume, plumpness, and hydration. However, natural HA levels decline with age, contributing to dryness and wrinkle formation. In skincare products, HA comes in different molecular weights: high molecular weight HA sits on the skin surface providing a moisture barrier, while low molecular weight HA can penetrate deeper for hydration within the skin. HA is extremely well-tolerated and suitable for all skin types. It is commonly found in serums, moisturizers, and sheet masks, and is also used in dermal fillers for volume restoration.

## Related Terms

Humectant: https://schoolofdermatology.com/glossary/humectant
Glycerin: https://schoolofdermatology.com/glossary/glycerin
Dermis: https://schoolofdermatology.com/glossary/dermis
Moisturizer: https://schoolofdermatology.com/glossary/moisturizer

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