Hydration & barrier · Entry 01
Dehydrated skin
Dehydration is a water problem, not an oil problem. The corneum has lost the free water it holds between cells — so skin can be visibly oily and dehydrated in the same hour, and usually is.
- How it reads
- Tight after cleansing. Fine lines that appear by evening and are gone by morning.
- Mechanism
- Loss of free water and natural moisturising factor from the stratum corneum
- Honest timeline
- 28 days to restored water-holding, with the first change in feel inside a week
- Often arrives with
- Compromised barrier · Dull skin · Excess sebum
Processes involved
The biology
underneath
- Natural moisturising factor depletionNMF — free amino acids, urea, lactates, PCA — binds water inside the cell. When filaggrin breakdown slows or surfactants wash NMF out, the corneum cannot hold water even when water is available.
- Transepidermal water lossWater moves from the dermis outward continuously. A disorganised lipid matrix lets it leave faster than skin can replace it — that is what TEWL measures, and what a good occlusive slows.
- Aquaporin downregulationAquaporin-3 channels move water and glycerol between keratinocytes. Their expression falls with age and with chronic barrier stress, so hydration reaches the upper layers more slowly.
Why it happens
- Over-cleansing with high-pH surfactants, which strips the natural moisturising factor.
- Low ambient humidity and indoor heating, which raise transepidermal water loss.
- Age-related decline in filaggrin breakdown, leaving fewer free amino acids in the corneum.
- Retinoid or acid use without a humectant and an occlusive alongside it.
When to see someone else
If tightness comes with cracking, weeping, or a burning that has not settled within a day, this is not simple dehydration. See a dermatologist before you add anything active.
What has evidence here
Each active carries its own entry in the library, with mechanism, origin and the products it appears in.
- Hyaluronic acidFermented · biotechtwo weightsTwo molecular weights, so the humectant works at two depths instead of pooling on the surface.See the ingredient
- EctoineFermented · halophile1.5%An extremolyte that forms a hydration shell around cell membranes and measurably lowers water loss.
- PanthenolBiotech3.0%Holds water and supports the lipid synthesis that keeps it there. Quietly one of the most evidenced things we use.See the ingredient
- Lavender hydrosolGrown · Geacawater phaseThe base of the formula rather than a fragrance in it, distilled four hundred metres from where it was cut.See the ingredient
Recommended ritual
Ritual de hidratare
Four steps, twice a day, judged at 28 days. Layered wettest to richest — a humectant with nothing above it evaporates and takes your water with it.