A serum is a light, highly concentrated liquid that delivers an active ingredient, such as vitamin C, niacinamide or retinol, to target a specific concern. A moisturiser is a cream, lotion or gel that hydrates the skin and slows water loss. Serum goes on first, straight after cleansing; moisturiser goes on top. Everyone benefits from a moisturiser, while a serum is optional and worth adding only if you have a clear goal.
Serums and moisturisers can look like they do the same job, and some products blur the line. The difference lies in what each is designed to do. Once you understand that, you can tell whether your skin care routine needs one, the other or both.
Serum vs Moisturiser at a Glance
| Serum | Moisturiser | |
|---|---|---|
| Main job | Treat a specific concern with a concentrated active | Hydrate and protect the skin barrier |
| Texture | Thin, light, water- or oil-based liquid | Thicker gel, lotion or cream |
| How much | A few drops for the whole face | A small fingertip amount or more |
| Order | After cleansing, before moisturiser | After serum, before sunscreen |
| Essential? | Optional | Yes, for almost everyone |
As Harvard Medical School dermatologist Dr Abigail Waldman explains in Harvard Health, a serum is not a moisturiser: it is a highly concentrated formula designed to sink in quickly and deliver an intensive dose of ingredients.
Which Serum for Which Concern?
| Concern | Serum ingredients to look for |
|---|---|
| Signs of ageing | Vitamin C with vitamin E and ferulic acid; retinol; niacinamide |
| Dark spots and uneven tone | Vitamin C, kojic acid, glycolic acid, niacinamide |
| Dryness and tightness | Hyaluronic acid, ceramides, vitamin E |
| Oiliness and spots | Niacinamide, salicylic acid |
Do You Need Both?
Use Both If…
You have a specific goal, such as fading dark spots or softening fine lines, and you want an active ingredient in a stronger dose than a moisturiser provides.
Moisturiser Only If…
You are happy with your skin, are on a tight budget, or have very sensitive skin that reacts to actives.
Serum Only?
Rarely a good idea. Most serums do not seal in moisture, and active serums can be drying, so follow with a moisturiser.
Oily Skin Exception
A hydrating serum plus a very light gel moisturiser, or a gel moisturiser alone, can be enough for oily skin.
How to Use Them Together
- Cleanse and pat your skin dry.
- Apply a few drops of serum and press it gently into your skin.
- Wait a moment until it feels almost absorbed.
- Apply your moisturiser, then sunscreen in the morning. Our guide to the order to apply skincare products covers the rest.
- Patch test any new serum first. Powerful ingredients can irritate sensitive skin.
Do not double up on acids. Harvard dermatologist Dr Maryam Asgari warns that combining, for example, a vitamin C serum with a retinol cream can irritate the skin. Use them at different times of day.
A Vitamin C Serum to Try
Vitamin C Serum by Harvest Twin Labs
A stabilised vitamin C serum designed to target visible signs of ageing and restore radiance. Vitamin C is one of the serum ingredients Harvard dermatologists highlight for helping prevent brown spots and supporting collagen. Use it in the morning after cleansing, then follow with moisturiser and sunscreen.
View ProductFrequently Asked Questions
Can a serum replace a moisturiser?
Usually not. Serums deliver active ingredients but most do not seal moisture in. Follow a serum with a moisturiser, unless your skin is very oily and a hydrating serum feels like enough.
Do serums work better than moisturisers?
They do different jobs. A serum targets a specific concern; a moisturiser keeps skin hydrated and comfortable. Neither replaces sunscreen.
Are expensive serums better?
Not necessarily. Harvard dermatologists say the active ingredients, formulation and stability matter more than price.
Can I use two serums?
You can, but use one in the morning and one at night, especially if both contain active ingredients.
Sources: Harvard Health Publishing, Skin serum: What it can and can't do (Dr Abigail Waldman, Dr Maryam Asgari); American Academy of Dermatology, How to pick the right moisturizer for your skin.