What is an anhydrous serum, and when does it beat a water-based one?

An anhydrous serum is a serum with no water phase. Where a conventional serum or cream is roughly 60 to 80 percent water, an anhydrous formula is built entirely from oils, lipids, esters and the actives dissolved in them. That difference decides three things: what the formula can carry, whether it needs a preservative system, and how it behaves once it meets the skin barrier.

Most skincare is mostly water. A review of cosmetic formulation puts water at more than two thirds of a typical formula, with lotions running higher still [1]. Water is cheap, it makes a product feel light, and it dissolves the water-soluble ingredients most people recognize. Everything else in the jar is there to hold that water in a stable structure and keep it from growing anything.

Anhydrous is the formulation term for a water-free product: oils, balms, powders and lipid-based serums [1]. "Serum" itself has no regulatory definition. Neither the FDA nor the EU cosmetics regulation recognizes it as a category, so the word describes a format and a concentration, not a standard [10]. An anhydrous serum, then, is a concentrated lipid formula that does the work people expect of a serum without a water phase to dilute it.

What water costs a formula

Water is where microbes grow. Cosmetics with a high water content are at risk of contamination, which is why manufacturers add preservatives to them [2]. Microbial growth depends on the water available in a product, and formulators use water activity as the measure. Below a threshold near 0.7, growth stops, and a product with no free water sits far below it [3]. That is why anhydrous formulas can be made without a traditional preservative system. The protection is passive, so it depends on the product starting clean and staying that way. The FDA lists fingers dipped into a jar and water introduced in use as the two common contamination routes [4], which is one reason a good waterless product still maintains an antioxidant system.

Water also sets the terms for the actives. Vitamin C is a clear example. L-ascorbic acid, the form used in most water-based vitamin C serums, has to be formulated below pH 3.5 to enter skin, and it is unstable in solution [5, 6]. A lipophilic ester such as tetrahexyldecyl ascorbate (THD ascorbate) dissolves in oil, penetrates, and is converted back to ascorbic acid by skin enzymes, with roughly 84 percent conversion measured in a laboratory skin model [7]. It is more stable in a formula than the free acid, though it is not immune to oxidation and still needs antioxidant protection alongside it [8]. Removing the water removes the environment in which the free acid degrades fastest.

Water-in-oil and oil-in-water products need emulsifiers to hold the two phases together, and emulsifiers are surface-active by design. In a human study, non-ionic emulsifiers in a cream altered water loss through normal skin, and the authors proposed that the emulsifiers had integrated into the stratum corneum lipid structure [9]. An anhydrous formula has no phases to reconcile and no emulsifier to carry.

What an anhydrous lipid serum does on skin

The outer skin barrier is a lipid structure. The stratum corneum is built from flattened cells held together by a lipid matrix of ceramides, cholesterol and free fatty acids in roughly equal molar proportions, arranged in stacked lamellar sheets [11]. Those lamellae are what hold water in and keep irritants out [12].

Lipids applied to the skin work in two ways. On the surface, an occlusive layer slows water loss. Below the surface, lipids that resemble the barrier's own enter the stratum corneum itself. Mixtures of ceramides, cholesterol and fatty acids in physiologic ratios have been shown to allow normal barrier repair in animal studies, and incomplete mixtures delayed it [14]. In a small clinical study, a ceramide-dominant emollient lowered water loss and restored the lamellar structure in children with eczema [15].

An anhydrous serum is the format in which those lipids are the whole formula. Squalene and wax esters are lipids unique to human sebum [16]. Squalane is the hydrogenated, oxidation-resistant form of squalene [17], and jojoba esters are derived from jojoba wax, the main botanical source of wax esters chemically related to those in sebum [18]. When built from materials like these, plus a ceramide and a lamellar-forming lipid, an anhydrous serum can deliver a barrier-shaped lipid system at full concentration, with oil-soluble actives dissolved in it.

When a water-based serum is the better choice

Water-based serums exist for good reasons.

The first is an active that needs water to dissolve. Niacinamide is water-soluble [19], and hyaluronic acid is a water-binding molecule that holds moisture in the skin [20]. Neither dissolves in oil. If the active you want is hydrophilic, the formula that carries it needs water.

The second is hydration itself. Humectants such as glycerin and hyaluronic acid pull water into the stratum corneum, which an oil cannot do. In dry conditions, though, humectants draw water from the dermis toward the surface, where it evaporates, which is why formulators pair them with an occlusive [13]. A water-based humectant serum works best with a lipid layer over it.

The third is order. A 2026 review of layering studies found that sequence changes penetration: pre-hydrating the skin with an aqueous product enhances delivery of water-soluble compounds, and applying an occlusive after a product can double penetration, while an occlusive applied first reduces delivery of what follows [21]. Water-based products go on first, and lipid-based products go on last.

The comparison in one place

	Anhydrous serum	Water-based serum
Water content	None	Typically 60 to 80 percent or more [1]
Preservation	No free water, so no traditional preservative system; antioxidants protect the oils [3]	Preservatives required [2]
Carries best	Oil-soluble actives: vitamin C esters, retinoids, lipids [7]	Water-soluble actives: niacinamide, hyaluronic acid, most acids [19, 20]
Hydration mechanism	Slows water loss; supplies barrier lipids [13, 14]	Adds water via humectants; needs an occlusive over it in dry air [13]
Emulsifiers	None	Required to hold oil and water together [9]
Place in a routine	Last	First, on clean skin

How Māteriā applies this

Omnia is an anhydrous solid serum. It has no water phase, so the whole formula is functional material: a lipid system built from squalane, jojoba esters, ceramide NP and a lamellar-forming phytosterol lipid, with the actives, including THD ascorbate, carried within it. The full ingredient list and the role of each material are on the Omnia page. The reasoning behind the barrier-first approach is on The Science of Biomimetic Design.

Sources

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Pinnell SR, Yang H, Omar M, et al. Topical L-ascorbic acid: percutaneous absorption studies. Dermatologic Surgery. 2001;27(2):137–142. https://pubmed.ncbi.nlm.nih.gov/11207686/
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Ochiai Y, Kaburagi S, Obayashi K, et al. A new lipophilic pro-vitamin C, tetra-isopalmitoyl ascorbic acid (VC-IP), prevents UV-induced skin pigmentation through its anti-oxidative properties. Journal of Dermatological Science. 2006;44(1):37–44. https://www.sciencedirect.com/science/article/abs/pii/S0923181106001952
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95%

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Fell in love

This product has blown me away. My skin felt amazing after the first use. Very moisturizing, but also this silky/smooth feeling that lasts the whole day. I've been using it for a week and have never needed to apply it more than once in the AM, even though I have a couple times ;). It's just really really comfortable and healthy feeling. I can't think of another product I've liked this much, this fast . Truly love it.

The best in the market

★★★★★

I absolutely love Omnia. I’ve tried a LOT of skincare over the years, and this is one of the rare products where I can genuinely see and feel a difference in my skin. It leaves my skin incredibly hydrated, smooth, and healthy-looking without needing a complicated routine or a million different products. I also really appreciate the thought and science behind the ingredients and formulation. My skin has never looked better, and I honestly recommend this to anyone who wants great skin without a 10-step routine!

From an 8-Step Routine to This. My Skin Has Never Been Better.

I’ve probably tried 30+ different skincare regimens over the years, from “organic/all natural” products to luxury and clinical-grade skincare. There are a lot of good products out there, but what I kept finding was that I needed an 8-step routine to get the results I actually wanted. And honestly, that gets exhausting, time-consuming, and expensive.

What made me fall in love with Omnia is the amount of care and research that has clearly gone into every part of the formula. Every ingredient has a purpose, the sourcing is intentional, the concentrations are thoughtfully chosen, and the science behind it isn’t just marketing language. It has actually SHOWN UP in my skin.

The biggest difference for me is that I no longer feel like I need a cabinet full of products to maintain my skin. I live in an extremely dry climate, so I still use HA for extra hydration, plus an eye cream, and then this. That’s it. My routine has gone from 8+ steps to 3, and my skin looks and feels better than it did with the much more complicated routines I was using before.

I constantly get compliments on my skin, especially on my hydration, elasticity, and overall complexion, and I genuinely believe Omnia has been the biggest contributor to that change.

I’m pretty skeptical when it comes to skincare because I’ve tried so much over the years, so when I find something that actually simplifies my routine AND delivers noticeable results, I’m all in. Omnia is one of those products for me. If you’re someone who has tried a million products and feels like you need a complicated routine to get good skin, this is absolutely worth trying.

One jar replaced several bottles

I was doing multiple serums, a moisturizer, a face oil and a night cream. Now I do this morning and night as the last step after one targeted serum. My skin definitely looks better than it did before, and the texture is delightful!

Bye bye flaky nose

I've had a permanent dry flaky patch on the side of my nose for years that I could never get rid of no matter what. A week of this, twice a day, and it's gone. GONE. I keep touching it. The rest of my face is softer and more even too but honestly the nose thing alone is worth it to me.

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