Moisturiser is the most-used skincare product and one of the least understood. The marketing surrounds it with luxury and high prices, yet the science of how it works is well established and refreshingly simple — and it turns out that an effective moisturiser can be inexpensive, while an expensive one is not automatically better.
Understanding the three basic jobs a moisturiser can do lets you see past the packaging and choose what your skin actually needs.
The three jobs: humectants, emollients, occlusives
Moisturisers work through three types of ingredient, often combined. Humectants, such as glycerin and hyaluronic acid, draw water into the outer skin and hold it there. Emollients, such as many plant oils and fatty acids, smooth and soften by filling gaps between skin cells. Occlusives, such as petrolatum and certain waxes, form a light barrier that slows water escaping from the skin.
Most good moisturisers blend these to both add hydration and help the skin retain it. That combination — bringing in water and stopping it leaving — is essentially all a moisturiser needs to do, and it is not a job that requires exotic or costly ingredients.
Why price rarely predicts quality
Because the core ingredients that make a moisturiser work are inexpensive and widely available, a modestly priced product can be every bit as effective as a luxury one. Much of the price difference in premium moisturisers reflects packaging, fragrance, marketing and brand positioning rather than superior function. Independent comparisons repeatedly find affordable moisturisers performing as well as far pricier ones.
This is genuinely good news: caring well for your skin does not require expensive products. It requires the right kind of product used consistently, and that is available at every price point.
Matching moisturiser to your skin
The main thing to match is texture to skin type and season. Drier skin generally does better with richer creams higher in emollients and occlusives; oilier or acne-prone skin often prefers lighter, non-comedogenic gels or lotions that hydrate without heaviness. Skin can also change with the seasons, needing more in cold, dry weather and less in humidity.
If your skin is persistently irritated, very reactive, or has a condition like eczema, that is worth discussing with a professional, since the right choice can be more specific. But for everyday healthy skin, the rule is simple: pick a well-formulated moisturiser whose texture suits you, ignore the price prestige, and use it consistently.
What the skin barrier actually is
Understanding what a moisturiser is doing requires a rough picture of what it acts on. The outermost layer of skin consists of flattened dead cells embedded in a lipid matrix, an arrangement frequently compared to bricks and mortar. The cells are the bricks; ceramides, cholesterol and fatty acids are the mortar.
This structure performs two jobs: keeping water in and keeping irritants and microbes out. When the lipid matrix is depleted — by harsh cleansing, cold dry air, over-exfoliation or certain skin conditions — water escapes faster and the surface becomes more permeable to things that irritate it.
Every moisturiser addresses this in one or more of three ways, which is the reason the three-category framework exists rather than being an arbitrary classification. Knowing which category a product is weighted toward is more informative than any marketing description of what it does.
Humectants and what they need to work
Humectants draw water toward the outer layer of skin. Glycerin is the most widely used and among the best evidenced; hyaluronic acid, urea, glycols and panthenol also fall into this group.
The detail that gets omitted is where the water comes from. In humid conditions humectants draw moisture from the air; in dry conditions they draw it from deeper in the skin, which can leave the surface feeling drier than before if nothing prevents that water from evaporating.
This is why a humectant-only product — most commonly a hyaluronic acid serum used alone — can make skin feel tighter in a dry climate or heated indoor environment. The fix is not to abandon it but to apply something over it that slows evaporation, which is what the third category does.
Emollients and the feel of skin
Emollients fill the gaps between skin cells, smoothing the surface and improving how skin feels and looks. This group includes plant oils, squalane, fatty alcohols, esters and silicones such as dimethicone.
Their contribution is partly cosmetic, in that much of the immediate improvement after applying a moisturiser is emollient effect, and partly structural, since several of them resemble the skin's own lipids closely enough to contribute to the matrix.
The most useful members of this group for a compromised barrier are ceramides, cholesterol and fatty acids, because these are the actual components of the lipid matrix rather than substitutes for it. A moisturiser containing them is doing something more targeted than one relying on general oils, which is one of the few formulation distinctions with reasonable support behind it.
Occlusives and where they belong
Occlusives form a physical layer that slows water loss from the surface. Petrolatum is the most effective of these by a considerable margin, followed by mineral oil, lanolin, waxes and dimethicone.
Petrolatum in particular has an unusually strong evidence base for reducing water loss, and it is inexpensive and among the least allergenic ingredients in common use. Its reputation suffers from associations with the petroleum industry that have no bearing on the purified cosmetic grade, which has been used safely for well over a century.
The practical application is layering: an occlusive applied over a humectant traps the water the humectant attracted, which is why the combination works better than either alone. For very dry skin, a thin layer of a heavy occlusive as the final evening step is one of the most effective and cheapest interventions available.
Why price predicts so little
The active components of a moisturiser are commodity ingredients: glycerin, petrolatum, dimethicone, fatty alcohols, ceramides. None is expensive to produce, none is proprietary, and all appear in products across the full price range.
What varies with price is the sensory experience, the packaging, the fragrance, the marketing and occasionally the inclusion of ingredients with limited evidence. A product costing many times another may feel considerably nicer and there is no reliable relationship between price and barrier function.
The test that cuts through this is to read the first five or six ingredients, which by convention are listed in descending order of concentration. If a well-evidenced humectant, emollient and occlusive appear near the top, the product will work. If the recognisable ingredients are a botanical extract at the bottom of the list, the price is buying the story.
Matching the product to the skin
Different skin types are best served by different weightings of the three categories, and this is where product selection actually matters. Oily skin generally does well with a humectant-heavy, low-occlusive formulation — a light gel or lotion — since the skin is producing its own occlusive layer.
Dry skin benefits from all three, with meaningful emollient and occlusive content, in a cream or ointment base. Very dry or eczema-prone skin frequently does best with an ointment, which is unpleasant to use during the day and highly effective overnight.
Combination skin does not require different products for different areas in most cases; a moderate lotion applied everywhere, with more on the drier areas, is usually sufficient. And skin that is oily and simultaneously flaky or tight is frequently a barrier problem rather than a type, which means the answer is a gentler routine rather than a different moisturiser.
The hydrating and moisturising distinction
Marketing draws a distinction between hydrating and moisturising that has some basis and is usually overstated. Hydrating conventionally refers to water content, addressed by humectants; moisturising to preventing loss, addressed by occlusives and emollients.
In practice almost every product contains elements of both, and the labels tell you very little about which predominates. The ingredient list does, which is why it remains the more useful thing to read.
Where the distinction genuinely matters is in the failure mode described earlier: applying only a humectant in dry conditions and finding skin feels worse. Recognising that as a missing occlusive rather than a defective product saves a good deal of confusion, and the fix costs nothing beyond applying something over the top.
Whether everyone needs one
It is worth saying that not everybody requires a separate moisturiser. Someone with balanced skin, using a gentle cleanser and a sunscreen with a moisturising base, may have adequate barrier function without adding anything.
The indication is how skin feels an hour after cleansing. Comfortable and unremarkable suggests no need. Tight, rough or itchy suggests a moisturiser will help, and the drier the sensation the more emollient and occlusive content is likely to be useful.
Seasonal variation is normal and worth accommodating: many people need considerably more in winter, when heated indoor air is dry, and little in summer. Changing product weight with the season is more sensible than using one formulation year-round and concluding it is either too heavy or insufficient. As with everything on this site, this is educational rather than medical advice, and persistent dryness that does not respond to a good moisturiser is worth having assessed.
Applying it at the right moment
Timing has a modest but real effect. Applying moisturiser to skin that is still slightly damp, within a few minutes of washing, gives humectants water to work with and gives occlusives something to seal in.
The effect is largest for very dry skin and for body application after bathing, where the difference between applying immediately and applying twenty minutes later is noticeable. For facial application the difference is smaller, and there is one important exception: retinoids and several other actives should go onto completely dry skin, because dampness increases penetration and irritation.
The general rule is therefore moisturiser onto damp skin, actives onto dry skin. Where both are used in the same routine, applying the active first to dry skin and the moisturiser afterwards handles both requirements without any waiting around.
The ingredients that add little
A moisturiser needs a humectant, an emollient and usually an occlusive. Everything beyond that is optional, and several common additions do more harm than good for a product used twice daily on a large area.
Fragrance, whether synthetic or from essential oils, is among the most frequent causes of contact allergy in cosmetics and contributes nothing to barrier function. Essential oils marketed as natural are not gentler; several are among the more common sensitisers. For anyone with sensitive or reactive skin, a fragrance-free product removes a meaningful proportion of the risk.
Botanical extracts present in trace amounts at the end of an ingredient list are there for the label rather than for any effect. Denatured alcohol high in a list can be drying in a leave-on product, though it is not a problem in every context. None of these makes a product unusable; they simply mean the price is buying things that are not doing the work.