Occlusion

Occlusion — the formation of a physical barrier on the skin's surface that slows the evaporation of water, a process known as transepidermal water loss. Occlusive ingredients help skin retain moisture and are commonly used in balms, ointments, and rich creams, especially for dry or compromised skin.

Key points

• Occlusion works by sealing in existing moisture rather than adding water to the skin.
• Common occlusive ingredients include petrolatum, mineral oil, shea butter, and various waxes and plant oils.
• It is often paired with humectants, which draw in water, and emollients, which soften the skin.
• Occlusives are frequently used in a practice called slugging, where a thin occlusive layer is applied as a final nighttime step.
• Heavily occlusive products may feel greasy and can trap heat or debris, which some people find uncomfortable.

Frequently asked

Is occlusion the same as moisturizing?

Not exactly; occlusion specifically reduces water loss by sealing the skin surface, whereas moisturizing more broadly can also involve adding or attracting water through other ingredient types.

Can occlusive products clog pores?

Some occlusives can feel heavy and may contribute to congestion in acne-prone skin, though ingredients like petrolatum are widely considered non-comedogenic; individual responses vary.

Related topics

• What Is a Humectant?
• What Is the Skin Barrier?

This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.