Which Hyaluronic Acid is Better: HMW or LMW?

Okay so if you have been anywhere near the skincare side of the internet in the last few years you have definitely come across hyaluronic acid. It is everywhere. Serums, moisturizers, toners, sheet masks, lip products, you name it, somebody has added hyaluronic acid to it. 

And honestly it deserves the hype because this one ingredient does ALOT for skin hydration. But what nobody really talks about clearly enough is the fact that hyaluronic acid comes in different molecular weights and they actually do different things to your skin. 

When people ask me which hyaluronic acid is better, the honest answer I give is that, it depends on what you are trying to do.  So understanding the difference between the two is probably the most important thing you can learn about this ingredient.

Well let me start from the beginning though because before we can even start talking about molecular weight we need to understand what hyaluronic acid actually is and why your skin needs it in the first place.

What Is Hyaluronic Acid and Why Does Your Skin Need It.

Hyaluronic acid is not something that was invented in a lab. It is something your body already makes on its own. It is a naturally occurring molecule that lives in your skin, joints, eyes, basically all the places that need to stay moist (yeah yeah yeah moist is a weird word) to work properly. 

In your skin specifically, hyaluronic acid sits between your cells and acts like a sponge, pulling in water and holding onto it so your skin stays plump, hydrated, and healthy looking. And when I say it holds onto water I mean it holds onto A LOT of water. The molecule is so good at attracting and binding water that it is classified as a humectant, which just means it is an ingredient that draws moisture to the skin and keeps it there.

Now here is where it gets a little sad. Your body produces hyaluronic acid naturally but as you get older it starts to decline. Research shows that hyaluronic acid levels in the skin start dropping from as early as your mid-twenties, and by the time you hit 50 your levels could be roughly half of what they were when you were younger. 

So all that plump dewy skin you had when you were younger? A big part of that was just your body making enough hyaluronic acid to keep everything hydrated without you even thinking about it. Once that production starts slowing down the skin begins to lose moisture, look dull, and that is when fine lines start showing up. This is exactly why hyaluronic acid became such a massive ingredient in skincare, because it was used to replenish what our skin was no longer making enough of on its own.

So Far So Good Right? Now Here Is Where It Gets Interesting

The part that most people skip over when they grab a random hyaluronic acid serum off the shelf is that as stated before, hyaluronic acid comes in different molecular sizes. And the size of the molecule completely changes how it interacts with your skin. Think of it like this: if your skin barrier is like a fence with tiny gaps in it, a big circle cannot squeeze through those gaps so it stays on the outside but a smaller circle can slip right through. That is literally the entire difference between HMW and LMW hyaluronic acid. One has big molecules and the other one has smaller molecules, and they do their work at completely different levels of the skin.

HMW stands for high molecular weight hyaluronic acid. These are the bigger molecules. They have a molecular weight above 1500 kiloDaltons which basically just means they are too large to pass through the skin barrier. 

So what do they do? 

They sit on the surface of your skin and form a hydrating film. That film locks moisture in and stops water from evaporating off your skin. It is instant, it is visible, and when you put it on your skin you can feel it working right away. Your skin feels smoother, softer, and more plump almost immediately. HMW hyaluronic acid is also the form that has more soothing properties so if your skin is irritated or sensitive this is the one that is going to calm things down on the surface.

LMW on the other hand stands for low molecular weight hyaluronic acid. These molecules are significantly smaller, usually below 100 kiloDaltons, and because of that smaller size they can actually penetrate deeper into the skin. They get past the outer barrier and deliver hydration to the lower layers of the epidermis more than HMW. 

The results are not instant in the way HMW is but they are longer lasting. LMW hyaluronic acid may support skin elasticity indirectly by improving hydration and can make fine lines look less visible overtime by plumping.

If you are looking at fine lines and want something that is going to work at a deeper level LMW is the one doing that heavy lifting.

So which One Is Actually Better?

I know people want a straight answer here so let me give you one, 

NEITHER one is better than the other on its own. 

They are just doing different jobs. HMW is your immediate surface hydration and barrier protection while LMW is your deep skin repair and long-term plumping. Trying to pick one over the other is like asking whether you need a roof on your house or a foundation. You need both.

And this is actually why the best hyaluronic acid products on the market combine multiple molecular weights in one formula. When you use a product that has both HMW and LMW working together you are getting surface hydration that locks moisture in right away AND deeper hydration that is repairing and plumping your skin from the inside. That is the real sweet spot and that is what you should be looking for when you are shopping for a hyaluronic acid serum or moisturizer.

The One Mistake That Ruins Everything

Now here is something I learned. Hyaluronic acid, regardless of whether it is HMW or LMW needs water to work. It is a humectant remember? It pulls water from its environment and holds onto it. So if you slap hyaluronic acid onto completely dry skin what do you think happens? 

It pulls water from the nearest source available which is your own skin. Especially during the dry season here in Ghana, applying hyaluronic acid without any moisture on your skin first is basically asking it to steal water from your deeper skin layers and bring it to the surface where it then evaporates into the dry air. The result? Your skin feels even drier than before you put anything on. I actually experienced this myself and I was so confused because I thought hyaluronic acid was supposed to be hydrating not drying me out 😂

The fix is simple though. Always apply hyaluronic acid to damp skin. After you cleanse just do not fully dry your face. Leave it slightly damp or use a mist or toner first, then apply your hyaluronic acid serum. And then, bossu (this is Ghanaian pidgin) this is the other part people forget, you need to seal it in with a moisturizer or an occlusive product on top. 

Something that creates a barrier between the hyaluronic acid and the air so the moisture it is holding does not just float away. Especially during the dry season, sealing in your hyaluronic acid with a good moisturizer or even a facial oil is not optional. It is the difference between your skin feeling amazing and your skin feeling like it aged ten years in one week.

How to Pick the Right Hyaluronic Acid Product

Now that you know HMW handles the surface and LMW handles the depth, here is what to actually look for when you are shopping. First check if the product lists multiple molecular weights or different forms of hyaluronic acid. You might see it listed as hyaluronic acid and sodium hyaluronate together on the ingredient list. 

Sodium hyaluronate is actually the salt form of hyaluronic acid and it is generally smaller in molecular size which means it penetrates deeper. So if you see both hyaluronic acid and sodium hyaluronate together that is a good sign that the product is working at multiple levels.

Second pay attention to concentration. Most effective hyaluronic acid products sit between 0.5% and 1%. Higher percentages aren’t always better and can feel sticky or irritate some people. A well-formulated product at 1% or below is going to do more for your skin than something marketing itself as super concentrated at 3%.

Third look at how the product is formulated overall. Hyaluronic acid works best when it is paired with other hydrating or barrier-supporting ingredients like ceramides, glycerin, or squalane. A serum that is basically just hyaluronic acid in water and nothing else is not going to give you the results you want. You want something that is formulated to actually deliver and hold that hydration, not just throw hyaluronic acid at your skin and hope for the best. (This is not pin the wheel)

The Bottom Line

Hyaluronic acid is genuinely one of the best ingredients you can add to your skincare routine. It works for basically every skin type, it is gentle enough for sensitive skin, and when used correctly it makes a real visible difference in how your skin looks and feels. But the key words there are when used correctly. 

Understanding that HMW and LMW do different things and that you ideally want both working together, knowing to apply it on damp skin, and sealing it in properly, that is what separates people whose hyaluronic acid is actually working from people who bought a serum, used it for two weeks, and then said it did nothing.

So next time you are looking at a hyaluronic acid product, do not just grab the one with the prettiest bottle. Check the molecular weight, check the formulation, and make sure you are using it the way it is supposed to be used. Your skin will thank you for it.