Glossary / Transepidermal Water Loss (TEWL)
measurement

Transepidermal Water Loss (TEWL)

The rate at which water passes through the skin to the surface and evaporates. A key marker of barrier function.

What It Is

Transepidermal Water Loss (TEWL) is the rate at which water moves from the inside of the skin to the surface and evaporates. This process occurs through the skin's outermost layer, the epidermis. It's a key indicator of the skin's barrier function.

How It Works

TEWL is measured using specialized equipment that calculates the amount of water lost from the skin over a set period. This rate can be affected by various factors, such as humidity, temperature, and skin condition. Researchers use TEWL measurements to assess the skin's natural barrier function and how it responds to different treatments or products.

Why It Matters

Understanding TEWL is crucial for skincare research because it helps scientists evaluate the effectiveness of products and treatments in maintaining or improving the skin's barrier function, which is essential for preventing dryness, irritation, and other skin issues.