Serums explained

A serum is a thin, concentrated product you apply after cleansing and before moisturizer. Because the molecules tend to be small and the active ingredients are packed in at higher levels, a serum is usually how you deliver something specific to your skin, like hydration, antioxidants, or peptides.

Where it goes in your routine

Most serums go on early, right after you cleanse, so the actives can reach the skin before heavier layers go on top. The general rule is serum before moisturizer. If a particular serum stings or feels too strong, applying it after your moisturizer can soften how much gets through, which some people find more comfortable while their skin adjusts.

A little goes a long way. Aim for less than a pea-sized amount, press it gently into the skin with your fingertips, and follow with moisturizer.

The main types

• Water-based: Light and quick to absorb. These carry water-loving ingredients like hyaluronic acid or niacinamide. They often don't seal moisture in on their own, so a moisturizer on top tends to help.
• Oil-based: Richer, and built around oil-loving ingredients like retinol or vitamin E. They can feel more substantial and often help lock in moisture.
• Biphasic: A blend of oil and water that separates in the bottle, so you shake before use. Suits most skin types.
• Gel: A refreshing, water or aloe-based texture that spreads easily. Often a comfortable pick for oily or combination skin.
• Single-ingredient: One or two actives, nothing extra. Easier to slot in if you want to keep things simple or avoid potential triggers, though not automatically better than a more complex formula.

One small habit worth keeping: don't let the dropper touch your face or fingers, so the bottle stays clean.

If you're not sure which serum fits your skin or how it plays with the rest of your shelf, it's worth checking ingredient compatibility before you layer several actives at once.