Hyaluronic acid can actually dry you out

Hyaluronic acid is sold as pure hydration, the ingredient you add when your skin feels dry. Most of the time it helps. But in the wrong conditions it does the opposite, and people end up tighter and flakier than before, blaming everything except the serum they added to fix it.

What it actually does

Hyaluronic acid is a humectant. It doesn't add water to your skin, it grabs water and holds it. A single molecule can bind many times its weight in water, which is why a few drops can plump the surface so quickly.

The catch is in that word: grabs. It has to pull the water from somewhere.

Where the water comes from

When the air around you is humid, hyaluronic acid pulls moisture from the air into your skin. That is the version everyone pictures, and it works beautifully.

When the air is dry, cold winter air, a heated room, an aeroplane cabin, there is little moisture to pull from the surroundings. So it does the next easiest thing and draws water up from the deeper layers of your own skin instead. That water then evaporates off the surface. You end up moving water out of your skin, not into it.

A humectant is only as good as the air around it, or the seal on top of it.

The fix is a lid, not more serum

This is why the standard advice matters more than it sounds:

• Apply it to damp skin, so there is water at the surface for it to hold onto.
• Seal it immediately with a moisturiser or a facial oil on top. The seal is what stops the water it grabbed from evaporating away.
• In very dry climates, lean less on it and more on ingredients that hold water without pulling it upward, like glycerin in a richer cream, or barrier fats such as ceramides.

Used naked on dry skin in dry air, hyaluronic acid is a leak. Used on damp skin and capped with a moisturiser, it is the hydration boost it is sold as.

What to do

Keep using it, just stop using it alone. Serum onto still-damp skin, moisturiser straight on top before it dries, every time. If your skin has felt tight since you added a hyaluronic serum, that is not a sign you need more of it. It is a sign there is nothing sealing it in.