Preservative

Preservative — an ingredient added to a product to prevent the growth of bacteria, mold, and yeast, keeping it safe and stable over its shelf life. Water-containing formulas are especially prone to contamination, which is why most creams, serums, and cleansers include one or more preservatives. Their type and level are carefully chosen to protect the product without unnecessarily stressing the skin.

Key points

• Preservatives protect water-based products from microbial contamination that could cause spoilage or infection.
• Common examples include phenoxyethanol, benzyl alcohol, sodium benzoate, and various organic acids.
• Anhydrous or waterless products may need little or no preservation because microbes require water to grow.
• Preservative choice balances effectiveness, stability, and the potential for skin irritation or allergy.

Frequently asked

Are preservatives necessary in skincare?

For most water-containing products they are essential, because without them microbial growth can make a product unsafe to use.

Can a product be truly preservative-free?

Waterless or single-use products can sometimes avoid added preservatives, but many still rely on ingredients that provide some antimicrobial protection.

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.