| Detail | Hyaluronic acid | Sodium hyaluronate |
|---|---|---|
| Chemical form | The acid form. | The sodium salt form. |
| Hydrating role | Attracts and binds water. | Functions in the same way to attract and bind water. |
| Relationship | A naturally occurring sugar polymer, meaning a long chain of sugar units. | A salt form of that polymer, rather than an unrelated ingredient. |
Hyaluronic acid occurs naturally in skin. Under conditions found in the body, it behaves more like its salt form. You may also encounter the name "hyaluronan," which covers both the acid and salt forms.1
Does hyaluronic acid molecular weight matter for hydration?
Yes. Molecular weight describes the molecule's size. Larger molecules hold more water but remain on the skin's surface. Smaller molecules hold less water but can penetrate a little deeper. High molecular weight hyaluronic acid has applications in surface hydration; smaller forms also have cosmetic applications because they can reach deeper skin layers.12
Choose by molecular size and the finished formula, rather than treating two ingredient names as rival political parties. A serum combining high and low molecular weights is a useful option. Check the packaging or manufacturer's website for molecular weight information instead of trying to decode it from the ingredient name alone.2
How should you use a hydrating serum?
- 1Cleanse your skin, leaving it damp.
- 2Apply the serum using the amount directed on its label. You can use a hyaluronic acid serum morning and evening.
- 3Follow immediately with moisturizer. Ingredients such as petrolatum, mineral oil or shea butter help keep the captured water from evaporating.
Which formula should you choose?
For dry skin, choose a cream or ointment rather than a lotion, even if the lotion has a very impressive vocabulary. Creams preserve more water than lotions, and ointments preserve more still. For oily skin, a lighter gel is an option. For combination skin, moisturize the dry areas rather than automatically covering the oily ones.3
If your skin is dry or sensitive, pay attention to the rest of the formula. Fragrance can irritate dry skin, and natural ingredients can aggravate allergies. A natural label does not mean a product is hypoallergenic.3
What results should you expect?
Expect improved hydration and modest softening of fine lines, not a complete reversal of skin aging. Some improvement can appear after about a week. If dryness persists despite moisturizing, or becomes painful, cracked, bleeding or very irritating, see a dermatologist.23
