How to Choose a Face Moisturiser

"Hydrating" is probably the most over-used word on a skincare shelf, and also one of the least precise. A moisturiser is not a single thing that does a single job — the good ones combine several mechanisms to put water into the skin and keep it there. Once you understand those mechanisms, choosing a face cream stops being a guessing game based on packaging and becomes a straightforward match to what your skin actually needs.

This guide explains what a moisturiser really does, the three ingredient types that make it work, how to choose one for your skin type, and how it fits with the rest of your routine.

What a moisturiser actually does

Behind the marketing, moisturisers work through three distinct mechanisms, delivered by three families of ingredients. A well-formulated cream usually uses all three [1].

Humectants — such as glycerin and hyaluronic acid — are water-loving molecules that draw water into the outer skin and hold it there, raising the water content of the stratum corneum. Emollients — such as squalane and plant oils — soften and smooth the surface by filling the gaps between skin cells, improving how skin feels and looks. Occlusives form a light film on the surface that slows water evaporation. Together they reduce transepidermal water loss — the constant, invisible evaporation of water through the skin — which is the core of what "moisturising" means [1].

This is why a good moisturiser is more than a nice texture: it is actively supporting the skin barrier, both adding water and helping the skin hold onto its own.

Dry vs dehydrated — an important difference

These two words are used interchangeably, but they describe different problems, and confusing them leads to buying the wrong product.

Dry skin is a skin type: it produces less oil (sebum), so it tends to feel tight, rough or flaky much of the time and generally benefits from richer creams with more emollients and occlusives. Dehydrated skin is a temporary condition — the skin lacks water, not oil — and it can affect any skin type, including oily skin. Dehydrated skin usually needs humectants and support to reduce water loss.

The practical upshot: someone with oily but dehydrated skin does not need a heavy cream; they need water-binding humectants in a light base. Knowing which problem you have is the difference between relief and a breakout.

How to choose by skin type

Start from your skin type and let the balance of the three ingredient families guide you.

Oily and combination skin. Yes, you still need to moisturise — skipping it can even prompt more oil. Choose a lighter, non-comedogenic formula that leans on humectants with lighter emollients, rather than heavy occlusives.

Dry skin. Reach for a richer cream that combines humectants with generous emollients and occlusives to both add water and seal it in. Barrier-supporting lipids matter most here.

Sensitive skin. Prioritise a short, fragrance-free formula with barrier-supporting and calming ingredients, and skip anything with a long list of strong actives.

Normal skin. A balanced daily moisturiser with a mix of all three ingredient types keeps things comfortable without heaviness.

Across every type, a handful of ingredients are worth recognising on a label: glycerin and hyaluronic acid (humectants), squalane and plant oils (emollients), and barrier-active ingredients such as ceramides and niacinamide.

The ingredients that strengthen the barrier

Two ingredients deserve a special mention because they do more than sit on the surface. Ceramides are lipids the skin already uses to build its barrier, so topping them up helps repair the "mortar" between skin cells. Niacinamide (vitamin B3) goes a step further: it has been shown to stimulate the skin’s own synthesis of ceramides and other barrier lipids and to reduce transepidermal water loss in dry skin [2]. A moisturiser built around these does not just hydrate for a few hours — it helps the skin hold water better over time.

How a moisturiser fits your routine

Order is simple: after cleansing (and any serum), a moisturiser is applied to seal in what came before, and in the morning sunscreen goes on top of it. Applying a moisturiser to slightly damp skin can help humectants work, and letting it absorb before the next step keeps everything comfortable.

A common and effective structure is a lightweight treatment serum followed by a moisturiser: the serum delivers targeted actives and water-binding ingredients, and the cream seals them in and reinforces the barrier. This layering tends to keep skin hydrated more reliably than either step alone. Morning and evening use suits most moisturisers.

The Ph.Doctor approach to moisturising

A moisturiser is where the Ph.Doctor line does its quietest but most important work, and its lipid cream is built to do the three jobs a good moisturiser should — draw in water, smooth the surface, and reinforce the barrier — while a vitamin C serum layers underneath to add hydration and antioxidant support.

The moisturiser itself is the Lipid facial cream.

Lipid facial cream is described on its card as "a universal cosmetic. Suitable for all skin types, including those sensitive or temporarily sensitized by dermatological therapies." It is built around barrier-supporting ingredients: "niacinamide," which the card says "strengthens the epidermal barrier" and "calms reactive skin," plus "squalane and rice oil," so "the skin regenerates faster, and the complexion is smooth and pleasant to the touch." Per the card’s tests, squalane "reduces transepidermal water loss TEWL by 18% after 28 days," and the finished cream "reduced TEWL by 34% after 4 weeks of use." It "leaves a satin finish and absorbs quickly," is "ideal as a make-up base," fragrance-free, "89% natural ingredients," vegan and "suitable for pregnant and breastfeeding women." Apply "every morning and evening" to cleansed skin.

To layer a water-binding, antioxidant step underneath, the Tetra C Serum goes on first.

Tetra C Serum has, per its card, "a multi-tasking effect. It moisturizes, evens out skin tone, lightens hyperpigmentation and has an anti-aging effect," and is built as "a synergy of 3 ingredients: Vitamin C + crocus extract + non-inflammable form of hyaluronic acid" — the hyaluronic acid being the humectant that binds water in the outer skin. It is "88% ingredients of natural origin," vegan and "suitable for pregnant and breastfeeding women." The card’s own instruction sets up the layering described above: "apply 3 to 5 drops to the face and neck in the morning and evening. Once the product is absorbed, use a Ph.Doctor moisturizer." Perform an allergy test before first use.

Used in sequence — serum first, then the lipid cream — they cover both halves of moisturising: adding water, and helping the skin keep it.

Frequently asked questions

What is the difference between dry and dehydrated skin?

Dry skin is a skin type that produces less oil, so it feels tight, rough or flaky over the long term and benefits from richer, more emollient creams. Dehydrated skin is a temporary lack of water that can affect any skin type — including oily skin — and needs humectants and reduced water loss rather than heavier oils. You can be oily and dehydrated at the same time.

Does oily skin need a moisturiser?

Yes. Oily skin still loses water and still has a barrier to support, and skipping moisturiser can even prompt the skin to produce more oil. The trick is the formula: choose a lighter, non-comedogenic moisturiser that hydrates without heavy occlusives, rather than skipping the step.

What ingredients should a good moisturiser contain?

Look for a mix of the three types: humectants such as glycerin and hyaluronic acid, emollients such as squalane and plant oils, and barrier-supporting ingredients such as ceramides and niacinamide. The exact balance depends on your skin type — lighter and humectant-led for oily skin, richer with more emollients and occlusives for dry skin.

How do I apply moisturiser in my routine?

After cleansing and any serum, apply your moisturiser to seal in what came before. In the morning, sunscreen goes on top as the final step. Applying to slightly damp skin can help humectants bind water, and letting each layer absorb keeps the routine comfortable.

Should I use a serum and a moisturiser, or just one?

They do different jobs and work well together. A lightweight serum delivers targeted actives and water-binding ingredients; the moisturiser seals them in and reinforces the barrier. Layering a serum under a cream tends to keep skin hydrated more reliably than either alone, though a single well-chosen moisturiser is fine if you prefer simplicity.

Can one moisturiser work for morning and night?

For many people, yes. Plenty of moisturisers suit both morning and evening use. Some prefer a lighter formula under daytime sunscreen and a richer one at night, but that is a preference, not a rule. The most important thing is daily consistency and, in the morning, following with SPF.

Why does my skin still feel tight after moisturising?

Usually it means the formula is not right for your skin, or the barrier needs more support. If a cream sits on top without relieving tightness, you may need more humectants (to bind water) and barrier-supporting ingredients, and to apply to slightly damp skin. Persistent tightness can also signal over-cleansing stripping the barrier.

Are natural or plant oils enough to moisturise on their own?

Not usually on their own. Oils are emollients and mild occlusives — they smooth the surface and slow water loss — but they do not add water. Without a humectant to bind water into the skin, an oil alone can feel nourishing yet leave skin dehydrated. A balanced moisturiser combines oils with humectants.

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Selected references

1. Rajkumar J, Chandan N, Lio P, Shi V. The skin barrier and moisturization: function, disruption, and mechanisms of repair. Skin Pharmacol Physiol. 2023;36(4):174–185. Describes how occlusives, humectants and emollients work — sealing the surface, drawing water into the epidermis, and assimilating into the stratum corneum — to strengthen the barrier and reduce transepidermal water loss.
2. Tanno O, Ota Y, Kitamura N, Katsube T, Inoue S. Nicotinamide increases biosynthesis of ceramides as well as other stratum corneum lipids to improve the epidermal permeability barrier. Br J Dermatol. 2000;143(3):524–531. Topical nicotinamide (niacinamide) increased ceramide, free fatty acid and cholesterol synthesis and decreased transepidermal water loss in dry skin.