Best Hydrating Serum (UK): How to Choose and Use One

A good hydrating serum is one of the most useful steps you can add to a routine: it delivers a concentrated dose of water-attracting ingredients that leave skin plumper, softer and more comfortable. Here's what makes a serum genuinely hydrating, how to choose one for your skin, and how to get the most from it.

What makes a serum hydrating?

Hydrating serums are built around humectants — ingredients that draw water into the upper layers of skin. The ones worth looking for:

• Hyaluronic acid — holds many times its weight in water; look for multiple molecular weights for hydration at different depths.
• Glycerin — a reliable, well-tolerated humectant that quietly does a lot of the work.
• Panthenol and niacinamide — support the barrier so skin holds on to that water for longer.

For the science of how this works, see what are humectants and how to hydrate skin.

How to choose one for your skin

• Oily or combination skin: a light, water-gel serum of hyaluronic acid and niacinamide feels weightless and won't add oil.
• Dry skin: look for a serum that pairs humectants with a little emollient support, and always seal it with a moisturiser.
• Sensitive skin: keep it simple and fragrance-free — glycerin and hyaluronic acid are gentle, reliable choices.

You can browse options in our hydration collection.

How to use a hydrating serum

Technique makes a real difference with humectants:

• Apply to slightly damp skin after cleansing — humectants pull in nearby water, so a damp base gives them more to work with.
• Always follow with a moisturiser. This is the step people miss: without something to seal it in, a humectant can draw water that then evaporates, especially in dry air. The moisturiser locks the hydration in.
• Use morning and night; finish the morning routine with SPF.

Hydrating serum vs moisturiser — do you need both?

They do different jobs. A serum delivers a concentrated hit of water-binding ingredients; a moisturiser seals that in and adds barrier support. For most people the best results come from using both — serum first, moisturiser on top — rather than choosing one.

Hydrating Serum FAQs

What is the best ingredient in a hydrating serum?

Hyaluronic acid and glycerin are the core humectants to look for, ideally supported by panthenol or niacinamide to help skin hold on to the water. Fragrance-free formulas suit sensitive skin best.

Should I use a hydrating serum before or after moisturiser?

Before. Apply the serum to slightly damp skin first, then seal it in with your moisturiser. Using it without a moisturiser on top means the hydration can evaporate, especially in dry air.

Can [[PROTECTED_70]] use a hydrating serum?

Yes, and it should. Oily skin can still be dehydrated. Choose a light, water-gel serum of hyaluronic acid and niacinamide, which hydrates without feeling heavy or greasy.

Do I need a hydrating serum if I already moisturise?

You don't strictly need one, but a serum adds a concentrated layer of humectants that a moisturiser alone doesn't, which is why many people use both for plumper, more comfortable skin.

How long until a hydrating serum works?

Hydration is fast — skin often looks plumper and feels more comfortable within days. Just keep sealing it in with moisturiser and applying to damp skin to keep the effect.