Serum

Serum — a concentrated, lightweight formula designed to deliver a high level of active ingredients to target specific concerns such as dullness, uneven tone, or signs of aging. Applied after cleansing and before moisturizer, it typically absorbs quickly and is formulated to address particular goals rather than provide broad surface hydration alone.

Key points

• Serums are generally more concentrated in active ingredients than toners, essences, or moisturizers.
• Popular actives include vitamin C, niacinamide, hyaluronic acid, peptides, and retinoids.
• They are applied to clean skin before richer products so the actives can absorb effectively.
• A moisturizer is often layered over a serum to seal in ingredients and support the skin barrier.

Frequently asked

Do I still need a moisturizer if I use a serum?

In most cases yes, because serums target specific concerns and often do not provide the occlusive properties that help seal in moisture. Layering a moisturizer over a serum supports hydration and barrier function.

Can I use more than one serum at a time?

Many people layer compatible serums, applying the thinnest first, though combining certain strong actives can increase irritation. Introducing one new serum at a time makes it easier to see how your skin responds.

Related topics

• Understanding Serums
• How to Choose a Cleanser
• Vitamin C Serum (Format Guide)
• Micro-Needling Serum (At-Home)
• Eye Serum
• Brow Serum
• What Goes First, Serum or Moisturizer?
• Should I Use Toner Before or After Serum?

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