The Ordinary Hyaluronic Acid

The Ordinary Hyaluronic Acid 2% + B5 is a water-based serum combining three molecular weights of hyaluronic acid with vitamin B5 (panthenol). The three molecular weights are important: low-weight HA penetrates to the upper dermis, mid-weight HA stays in the epidermis, and high-weight HA sits on the surface as an occlusive film. Together they hydrate at multiple skin layers simultaneously. Vitamin B5 is added as a surface-smoothing agent that also supports the skin barrier. At 2% total HA, this is a higher concentration than many HA serums on the market, though concentration alone does not determine efficacy - the weight distribution matters as much.

The Hyaluronic Acid 2% + B5 comes in 30ml and 60ml formats. The 30ml is the standard-sized serum for a solo user at twice-daily use, lasting approximately two to three months. The 60ml is more economical per ml and makes sense if you have confirmed the formula suits your skin, if you use HA as a daily staple rather than an occasional step, or if multiple people in a household share skincare. There is no formula difference between the two sizes. The 46+ items in the collection include multiple listing variants of both sizes, some of which are recent arrivals or reformulations; the core formula has remained substantially consistent.

Marine Hyaluronics is a separate product from the Hyaluronic Acid 2% + B5. It uses a low molecular weight hyaluronic acid derived from plankton, which means the molecule is smaller and absorbs more rapidly. The formula is lighter and more watery than the standard HA serum, and does not include vitamin B5. Marine Hyaluronics is well suited to oily or gel-texture-preferring skin types that find the standard HA 2% + B5 slightly too thick. It is also a useful prep layer applied to damp skin before the regular HA serum if you want multi-step HA layering. At 30ml it is the same size as the smaller standard HA format.

Alpha Arbutin 2% + HA adds The Ordinary's brightening active to a hyaluronic acid vehicle. Alpha arbutin is a glycosylated form of hydroquinone that inhibits tyrosinase activity, which reduces melanin production. It is used to target hyperpigmentation, post-acne marks, and uneven skin tone. The HA in this formula is a carrier that also hydrates as alpha arbutin works on the pigmentation concern. This product is not purely a hydration serum; it is a targeted treatment that happens to include HA. If pigmentation is not a concern, the plain Hyaluronic Acid 2% + B5 or Marine Hyaluronics is the appropriate product.

All three hyaluronic acid products from this collection are applied after water-based cleansing and toner, on slightly damp skin. This is important: hyaluronic acid draws moisture from its environment, and applying it to completely dry skin in a dry environment can pull moisture upward from the dermis and away from the skin surface, temporarily increasing dryness. Applying to damp skin gives the HA molecules sufficient moisture to bind. After the HA layer sinks in (30 to 60 seconds), apply your remaining water-based serums, then emulsion or cream to seal the moisture in. In a morning routine, SPF follows as the last step.

You can layer Marine Hyaluronics and the standard Hyaluronic Acid 2% + B5 in the same routine. Apply Marine Hyaluronics first to damp skin for rapid penetration of the low-weight HA, then apply HA 2% + B5 while the surface is still slightly wet. The surface-film action of the higher-weight HA in the 2% + B5 will lock the lighter molecules in. This is a valid approach for very dry or dehydrated skin, though most people will find the standard HA 2% + B5 alone sufficient.

The 46+ items in this collection include what appear to be duplicate or near-duplicate listings of the same product. These arise from several causes: different import batch label variants (some shipped with Korean-translated outer packaging, some with English-only), minor reformulations that generated new SKUs, and listing variants for "recent arrival" restocks. When the core product name and size are the same (e.g., Hyaluronic Acid 2% + B5 30ml), the formula is the same regardless of listing name variations. If you are uncertain which listing to choose, select the one with the most recent "added" date or contact skinsli support to confirm the current stock batch.

Oily skin: Marine Hyaluronics 30ml is the lightest option and least likely to feel heavy. If you want the B5 surface-smoothing benefit, try HA 2% + B5 30ml after Marine Hyaluronics. Dry skin: HA 2% + B5 60ml is the workhorse; follow with a cream or face oil to prevent the HA from drawing moisture upward as it dries. Combination skin: Marine Hyaluronics on oily zones, HA 2% + B5 on dry zones, or alternate products by routine (morning vs. evening). Skin with hyperpigmentation: Alpha Arbutin 2% + HA is the targeted choice; use it consistently for six to twelve weeks before assessing results.