Skin & Grooming · Explainer
What a Moisturizer Is Actually Doing
Three mechanisms, three types of ingredient, and why the $12 tub is usually as good as the $90 one.
By Julien Malet, · Updated 2026-09-08
Moisturizer is the most marked-up product in skincare and one of the simplest. Once you know the three mechanisms, the price range stops making sense — in a useful way.
The three jobs
Occlusives sit on the surface and reduce water loss. Petrolatum is the most effective occlusive there is, and it costs almost nothing. Also dimethicone, mineral oil, shea butter, lanolin.
Humectants pull water into the outer skin layer. Glycerin, hyaluronic acid, urea, panthenol. Glycerin is the workhorse; hyaluronic acid is the one with the marketing budget.
Emollients fill gaps between skin cells so the surface feels smooth. Fatty acids, esters, squalane, and ceramides.
A good moisturizer does all three. Most decent ones do.
Why ceramides get named specifically
Ceramides are lipids that make up a large share of the mortar between your skin cells — the "bricks and mortar" model of the skin barrier. Skin low in ceramides loses water faster and is more reactive, which is why they are central to eczema care.
Ceramides in a moisturizer are genuinely useful. They are also not exotic — CeraVe built an entire brand on cheap, well-formulated ceramide products, and dermatologists recommend them because they work, not because they are advanced.
Worth knowing, though: ceramides are one route to a repaired barrier, not the only one. A simple petrolatum-and-glycerin cream with no ceramides at all reduces water loss more effectively than most ceramide serums, because occlusion is the blunter and stronger mechanism. If your barrier is genuinely compromised, that is the thing that fixes it fastest.
Hyaluronic acid, honestly
Hyaluronic acid is a humectant. It holds a lot of water, which is real and gets exaggerated into something magical.
Two caveats worth knowing. Topical HA works in the outer layers — the molecule is far too large to reach the dermis where injected fillers go, and no serum plumps skin the way a filler does. And in dry air, a humectant with nothing sealing it can draw water from deeper skin and let it evaporate, which is why HA serums feel tight without a moisturizer over them.
Use it under an occlusive, or skip it. It is not the active ingredient the pricing implies.
What the price buys
Above roughly $15–20, you are mostly buying texture, fragrance, packaging and brand.
The genuinely differentiated things a more expensive product might have: a well-formulated retinoid, a stabilised vitamin C, or a niacinamide at a real concentration. Those are actives, not moisturizing.
For barrier repair and water loss? Petrolatum, glycerin and ceramides. All cheap, all decades old, all on the drugstore shelf.
Fragrance
Fragrance is the most common cause of contact allergy in skincare. It adds nothing functional.
"Unscented" and "fragrance-free" are not the same: unscented can mean masking fragrance was added to cover a raw-material smell. Fragrance-free is the phrase to look for. If your skin is reactive, this is the highest-leverage change you can make, ahead of any active.
Building it
Two products cover almost everyone:
A basic fragrance-free cream with ceramides and glycerin, night and morning. In a tub if your skin is dry, a lotion if it is oily. Tubs are better value; pumps are more hygienic.
A separate morning sunscreen. Moisturizer-with-SPF is a compromise — people apply far less than the amount SPF testing assumes, so the real protection is well below the number. Use a dedicated sunscreen.
That is a complete routine, plus a retinoid if you want the one active with real evidence behind it.