Transepidermal Water Loss (TEWL)
Transepidermal Water Loss (TEWL) — the natural process by which water moves from the deeper layers of the skin to the surface and evaporates into the air. A certain amount is normal, but elevated levels can indicate a compromised skin barrier and contribute to dryness.
Key points
- TEWL refers to the passive evaporation of water through the outermost skin layer, the stratum corneum.
- A healthy, intact barrier keeps TEWL at a low, balanced level.
- Increased TEWL is often a sign of a weakened or damaged skin barrier.
- Factors like low humidity, over-exfoliation, and harsh cleansing can raise TEWL.
- Moisturizers with occlusives and emollients help reduce excess water loss.
Frequently asked
How can I reduce transepidermal water loss?
Supporting the skin barrier with gentle cleansing and moisturizers containing occlusives, emollients, and humectants can help limit excess water loss.
Is some transepidermal water loss normal?
Yes; a baseline level of water loss is completely normal, and only elevated TEWL tends to signal a compromised barrier.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
