What Is Sodium Hyaluronate Crosspolymer-4?
Sodium Hyaluronate Crosspolymer-4 is a modern form of hyaluronic acid, a sugar naturally found in skin that binds water. Chemists take standard sodium hyaluronate and react it with a small linking agent called 2,2′-[1,4-butanediylbis(oxymethylene)]bis[oxirane]. This step connects many individual hyaluronic acid chains into a three-dimensional net, turning the fluid ingredient into a soft gel that stays longer on the skin. The crosslinked form resists breakdown and can hold moisture even better than its unmodified cousin.
Since the early 2000s brands have looked for ways to give longer lasting hydration without heavy oils. Crosslinked hyaluronic acid answered that need, and Sodium Hyaluronate Crosspolymer-4 quickly appeared in premium moisturizers and anti aging serums. Today it is produced in controlled reactors where purified sodium hyaluronate, water and the epoxy linker mix under gentle heat. After the reaction finishes the gel is neutralized, filtered and dried into a fine powder that easily redisperses in water-based formulas.
You will see this ingredient in lightweight serums, sheet masks, night creams, eye gels, after-sun lotions, primers and even hydrating mists. Its ability to form a flexible film makes it popular in products that promise plump smooth skin throughout the day.
Sodium Hyaluronate Crosspolymer-4’s Cosmetic Benefits/Uses
This multitasking molecule enhances both how a product feels and how skin looks
- Humectant – draws water from the environment and from deeper skin layers to the surface. This boosts immediate moisture levels giving skin a dewy appearance
- Skin Conditioning – forms a breathable film that smooths rough patches softens fine lines and improves overall texture so skin feels supple
- Emollient – fills in tiny gaps between skin cells reducing flakiness and leaving a silky afterfeel without the weight of traditional oils
Who Can Use Sodium Hyaluronate Crosspolymer-4
This ingredient is gentle enough for nearly every skin type. Dry complexions love its water binding power, oily and acne-prone skin benefit from its weightless feel and even sensitive skin usually tolerates it because it is non fragrant and non reactive. There are no known skin types that must avoid it, though people with a history of allergies to hyaluronic acid derivatives should be cautious.
Sodium Hyaluronate Crosspolymer-4 is produced by fermenting plant sugars with friendly bacteria then crosslinking the resulting hyaluronic acid, so it contains no animal material. That makes it suitable for both vegans and vegetarians.
Topical use is generally viewed as safe during pregnancy and while breastfeeding because the large crosslinked network stays on the surface and is not absorbed into the bloodstream. This is not medical advice and anyone who is pregnant or nursing should review all skincare products with a qualified doctor before use to be sure.
The ingredient does not make skin more sensitive to sunlight and can be worn day or night. It also plays well with common actives like vitamin C retinol and exfoliating acids, adding hydration without interfering with their performance.
Potential Side Effects/Adverse Reactions
Reactions to topical Sodium Hyaluronate Crosspolymer-4 differ from person to person. The points below outline potential issues, but they are uncommon when the ingredient is used correctly in a well-formulated product.
- Mild redness or stinging on very reactive skin
- Temporary itching if applied to broken or compromised skin
- Rare allergic response such as swelling or hives
- Breakouts if the finished product also contains heavy oils that trap sweat and debris
- Product spoilage leading to irritation if the preservative system fails
If you experience any ongoing discomfort stop using the product and seek advice from a healthcare professional.
Comedogenic Rating
Rating: 0/5 – Sodium Hyaluronate Crosspolymer-4 is water-soluble and forms a light breathable film that does not clog pores. It lacks oily or waxy components that normally trigger congestion, so it is considered non-comedogenic.
That makes it suitable for acne-prone or breakout-prone skin. The only caveat is that the overall formula matters; if the finished product pairs this ingredient with heavy oils the comedogenic profile can change.
Summary
Sodium Hyaluronate Crosspolymer-4 acts as a humectant, skin conditioner and emollient. Its crosslinked structure lets it grab and lock water at the surface, smooth rough spots and leave a soft silky feel without grease. This network also resists enzymatic breakdown so the hydration effect lasts longer than regular hyaluronic acid.
Once seen only in premium serums, it is now popping up in everything from sheet masks to tinted moisturizers as brands chase light yet long-lasting hydration.
Topical use is regarded as very safe with low risk of irritation or allergy for most people. As with any new skincare ingredient it is smart to patch test a product before full use just to be sure your skin agrees.