How do I know if my skin is dry or dehydrated?

Dry skin lacks oil and flakes. Dehydrated skin lacks water: it feels tight but looks smooth, and it happens on oily skin too. If your face is shiny by midday and still feels tight, you are dehydrated rather than dry, and a gel-cream will do more than a balm.

Can I use a moisturiser under makeup?

Yes, but the weight decides whether the makeup survives. A gel-cream that absorbs in a minute or two takes foundation fine. A heavy balm keeps moving under it, which is what makes foundation separate across the day.

Does drinking water fix dehydrated skin?

Not on its own. Drinking water is good for you and does almost nothing visible to the outer layer of skin, which loses water to the air rather than to the body. What changes it is putting water on and then something over the top to slow it evaporating.

The answer

My face is so dry — what actually helps?

If your skin feels tight and looks dull, you are probably dehydrated rather than dry, and a water-based gel-cream fixes it faster than a heavy balm. If it flakes and feels rough, that is dryness, and it wants an occlusive cream that stays put. Most people buy the second when they need the first.

What answers it

CliniqueMoisture Surge 100H hydratorThe gel-cream for dehydration. It sinks in fast enough to put makeup over, which is the specific reason it beats a balm on a morning you are getting ready.Buy on Amazon
Kiehl'sUltra Facial CreamThe cream for actual dryness. Fragrance-free and light enough not to slide under makeup, which rules out most creams at this weight.Buy on Amazon
Elizabeth ArdenEight Hour Cream skin protectantFor the patch that has already cracked — a lip, a cuticle, the side of a nose after a cold. Not a face routine, a repair.Buy on Amazon

Prices live on Amazon, where they change hourly — so we never quote one. Every product here is a brand we would name out loud.

Dry and dehydrated are not the same thing

Dry skin lacks oil: it flakes, feels rough, and gets worse in winter. Dehydrated skin lacks water: it feels tight, looks flat, and can happen on oily skin — which is why people with shine buy the wrong product for years. The test is simple. Press a cheek. If it feels tight but looks smooth, that is water. If it looks flaky, that is oil.

Why the heavy cream sometimes makes it worse

An occlusive balm seals what is underneath it. If there is no water underneath, it seals in nothing and the tightness stays — and now makeup slides. That is the usual story behind "nothing works on my skin". The fix is not more product, it is water first and something over it to hold the water there.

What to do the night before somewhere you care about

Nothing new. A face that has never met a product before is not the face to test it on the day of an event, and reactions show up at hour six rather than hour one. Use what you already know behaves, and put the novelty somewhere that cannot fail you — a lipstick, a nail colour.

Questions

How do I know if my skin is dry or dehydrated?: Dry skin lacks oil and flakes. Dehydrated skin lacks water: it feels tight but looks smooth, and it happens on oily skin too. If your face is shiny by midday and still feels tight, you are dehydrated rather than dry, and a gel-cream will do more than a balm.
Can I use a moisturiser under makeup?: Yes, but the weight decides whether the makeup survives. A gel-cream that absorbs in a minute or two takes foundation fine. A heavy balm keeps moving under it, which is what makes foundation separate across the day.
Does drinking water fix dehydrated skin?: Not on its own. Drinking water is good for you and does almost nothing visible to the outer layer of skin, which loses water to the air rather than to the body. What changes it is putting water on and then something over the top to slow it evaporating.