Is my skin dry or dehydrated?

What is the difference between dry and dehydrated skin?

Dry is a lipid problem. The barrier's mortar, roughly half ceramides, a quarter cholesterol and a quarter free fatty acids, is running short, so the surface is rough, the light scatters off it and it looks dull. Dehydrated is a water problem. The stratum corneum is not holding enough water to stay pliable, so it feels tight, shows fine crinkling when you pinch it, and can sit under a perfectly normal amount of oil. Dry is a type. Dehydrated is a state, and it comes and goes with the weather and the cleanser.

How can you tell which one you have?

Look for the pattern, not one sign.

• Rough, flaky, dull, and the same in every season: dry.
• Tight after washing, fine lines that appear by afternoon, oily by evening: dehydrated.
• Both at once: dry skin that has also been over-cleansed. Common.
• Pinch the cheek gently. Crinkling that takes a moment to settle points to water, not lipid.

What fixes dry skin?

Lipids, all three, in ratio. The 1996 work by Man, Feingold, Thornfeldt and Elias found that applying only one or two of the barrier lipids delayed recovery, while complete mixtures of ceramides, cholesterol and free fatty acids allowed normal recovery and skewed ratios accelerated it. In aged skin, Zettersten and colleagues found in 1997 that the cholesterol-dominant mixture significantly accelerated barrier recovery in human volunteers aged around 80 at 6 hours. A ceramide-only product is not the same category of thing. Look for all three on the label.

What fixes dehydrated skin?

Two things. First, stop the leak: a cleanser at low pH on a mild surfactant, lukewarm water, and no exfoliating acid until the tightness stops. Second, a humectant that skin recognizes. Glycerin binds water in the stratum corneum, and skin makes and moves its own glycerol through aquaporin-3 channels, which is why applied glycerin behaves like something the tissue already has a use for. The 2008 review by Fluhr, Darlenski and Surber in the British Journal of Dermatology collects the evidence: improved hydration, barrier function and mechanical properties, and protection against irritants. Seal it with lipids and the water stays.

Can oily skin be dehydrated?

Yes, and it is the most common version, because oily skin gets washed the hardest. Sebum is not water. A barrier that is losing water can sit under plenty of oil, which is why some faces shine and flake at the same time. The fix is a gentler cleanser and a humectant, and a light barrier cream at night. The instinct to strip the oil off is the thing making it worse.

What we made with it

Clean Slate is the cleanser that stops the leak: low pH, sodium cocoyl isethionate, glycerin. Baby's Bottom is the lipids: ceramides, cholesterol and free fatty acids in a 3:1:1 style ratio, with squalane and wax esters. Dry skin uses the cream twice a day. Dehydrated skin fixes the cleanser first and uses the cream at night. Both kinds of skin stop apologizing for their wash.

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