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Marine Hyaluronics

Marine Hyaluronics

Product Description

Product overview

Made in Canada INDIE

An ultra-lightweight, water-like serum powered by 23% active marine-derived water reservoirs — including exopolysaccharides from Antarctic bacteria, Hawaiian red algae, micro-filtered blue-green algae, and 11 skin-supporting amino acids — that attract and hold moisture the way hyaluronic acid does, but with a far lighter, non-tacky texture suited to all skin types.

Vegan Cruelty-Free Fragrance-Free Silicone-Free Oil-Free Paraben-Free Sustainably Sourced Marine Actives 23% Active Concentration
Pregnancy
Caution
Fungal Acne
No
Comedogenic
1/5
Volume
30 ml
pH Level
4.0 – 5.0
Active Conc.
23%
Vegan
Yes
Cruelty-Free
Yes
Real reviews · YouTube Shorts
Why it's different

Marine-Derived Hyaluronic Alternatives

Pseudoalteromonas exopolysaccharides from Antarctic marine bacteria, Hawaiian red algae (Ahnfeltia concinna), and micro-filtered blue-green algae function as HA-alternatives, drawing water into the skin's surface without tackiness.

The Ordinary Marine Hyaluronics – Product Page
01

Texture & feel

SENSORY
Consistency
Ultra-Watery Serum
Scent
Fragrance-Free
Absorption
Instant / Like Water
Finish
Dewy, Non-Sticky

Marine-Derived Hyaluronic Alternatives

Pseudoalteromonas exopolysaccharides from Antarctic marine bacteria, Hawaiian red algae (Ahnfeltia concinna), and micro-filtered blue-green algae function as HA-alternatives, drawing water into the skin's surface without tackiness.

11 Skin-Identical Amino Acids

Arginine, glycine, alanine, serine, valine, isoleucine, proline, threonine, histidine, phenylalanine, and aspartic acid replicate the skin's Natural Moisturizing Factor (NMF), reinforcing hydration from within.

23% Active Ingredient Concentration

At pH 4.0–5.0, the formula delivers a clinically relevant density of actives — significantly above industry norms for hydrating serums at this price point.

Zero-Weight Layering Serum

The water-like texture absorbs instantly with no pilling, no residue, and no interference with subsequent actives — ideal for complex multi-step routines including retinol, vitamin C, and AHA/BHA.

Sustainably Sourced Marine Actives

All marine-derived ingredients in the formula are sourced using sustainable harvesting practices, certified by DECIEM's environmental standards.

NMF-Matched Humectant Complex

Sodium PCA, PCA, sodium lactate, and glycerin mirror the composition of the stratum corneum's own moisture-retaining compounds, supporting barrier function alongside deep hydration.

02

Safety & compatibility

SAFE
Pregnancy & Breastfeeding

Generally considered safe due to the absence of retinoids, hydroquinone, and high-dose chemical sunscreens. However, the formula contains a low concentration of salicylic acid (listed near the end of INCI, used as a preservative/pH adjuster rather than an exfoliant). Most dermatologists consider trace topical salicylic acid safe, but consult your OB-GYN before use.

Fungal Acne (Malassezia) Safety

NOT considered fungal-acne safe. The formula contains Polysorbate 20, an emulsifier known to feed Malassezia yeast. Those with confirmed fungal acne (pityrosporum folliculitis) should choose a Polysorbate-20-free alternative. The salicylic acid present at low concentration may partially offset this, but is unlikely to counterbalance the issue.

Comedogenic Rating: 1/5 (Non-Comedogenic)

The formula is essentially oil-free and built on water, glycerin, and amino acids — all rated 0 on the comedogenic scale. The trace polysorbate 20 (rated 0) and propanediol (rated 0) pose no pore-clogging risk. Safe for acne-prone and clog-sensitive skin types.

Retinol / Vitamin A Compatible

Marine Hyaluronics is fully compatible with retinoids and retinol. Apply Marine Hyaluronics first on clean skin, then layer your retinol or retinoid on top. Its hydrating base helps buffer potential retinol-induced dryness and irritation.

AHA / BHA Compatible

Safe to combine with AHAs (glycolic, lactic acid) and BHAs (salicylic acid). Apply Marine Hyaluronics after acids have fully absorbed. The product's pH (4.0–5.0) is compatible with most acid formulations without interference.

Vitamin C Compatible

No conflict with L-ascorbic acid or ascorbyl derivatives. For best results, apply Marine Hyaluronics before your vitamin C serum if both are in the same routine step, or use vitamin C in the AM and Marine Hyaluronics in the PM.

Niacinamide Note

The Ordinary notes this product conflicts with their 100% Niacinamide Powder only. Standard niacinamide serums (like The Ordinary Niacinamide 10% + Zinc 1%) can be used in the same routine without issue.

Sensitive Skin Friendly

Completely fragrance-free, essential-oil-free, dye-free, and silicone-free. The formula has a very low irritation potential score. Patch test recommended for reactive skin, but the amino acid and marine base makes this one of the most universally tolerated serums in The Ordinary lineup.

03

Ingredient breakdown

INGREDIENTS

Pseudoalteromonas Exopolysaccharides & Ferment Extract ~4–6%Proven

The star actives of this formula. Exopolysaccharides are long-chain polysaccharides secreted by marine bacteria (Pseudoalteromonas) found in cold Antarctic ocean waters. They function as marine alternatives to hyaluronic acid by forming a moisture-retaining film on skin's surface. The ferment extract adds skin-soothing and barrier-supporting bioactive compounds generated during bacterial fermentation.

  • Mechanism: Film-forming humectant that binds water molecules and delivers immediate, long-lasting surface hydration
  • Clinical data: Lipotec's Hyadisine (a comparable exopolysaccharide) showed hydration improvements and reduction in wrinkle appearance comparable to hyaluronic acid in clinical studies
  • Texture advantage: Unlike traditional HA, provides hydration without the characteristic tackiness or pilling reported by users of HA 2% + B5
  • Sourcing: Sustainably harvested from Antarctic marine microorganism cultures
Non-comedogenic, fragrance-free, and suitable for all skin types including sensitive and dehydrated skin.

Ahnfeltia Concinna Extract (Hawaiian Red Algae) ~1.6–2.5%Proven

A red marine algae extract sourced from Hawaiian coastal waters. Ahnfeltia concinna is rich in polysaccharides that help skin attract and retain moisture. According to ingredient manufacturer Indeed Laboratories, it mildly stimulates circulation and enhances penetration of humectants like hyaluronic acid into deeper skin layers. It also provides structural support to help thicken and stabilize the formula.

  • Function: Skin protectant, humectant, and mild circulation stimulant
  • Synergy: Works alongside Pseudoalteromonas extracts to deliver multi-source marine hydration
  • Additional benefits: Antioxidant properties observed in in-vitro studies; may reduce skin roughness with consistent use

Glycerin ~3.8–5.7%Proven

A foundational humectant and skin-identical ingredient found naturally in human skin. Glycerin draws water from the environment and deeper skin layers toward the stratum corneum. A 2016 dermatological study found glycerin to be more effective as a humectant than AHAs and hyaluronic acid at equivalent concentrations. It also helps maintain lipid bilayer integrity between skin cells.

  • Comedogenicity: 0/5 — safe for all skin types including acne-prone
  • Effective concentration: Research shows benefits starting at 3%; this formula delivers within that range
  • Barrier support: Helps maintain the skin's natural moisture barrier, reducing transepidermal water loss (TEWL)
Best applied to damp skin (after misting with water or toner) to maximize humectant draw of moisture.

Amino Acid Complex (11 NMF Amino Acids) ~8–12% combinedProven

Marine Hyaluronics contains eleven skin-identical amino acids: arginine, glycine, alanine, serine, valine, isoleucine, proline, threonine, histidine, phenylalanine, and aspartic acid. These collectively mirror the Natural Moisturizing Factor (NMF) composition found in healthy skin, replenishing lost hydration factors that are depleted by washing, UV exposure, and ageing.

  • Arginine (~1.4–2.1%): Positively charged amino acid, excellent film former on skin. Builds collagen, speeds wound healing, and functions as a natural moisturizing factor component
  • Glycine (~1.2–1.8%): Anti-aging and wound-healing properties; supports collagen structure and hydrates stratum corneum
  • Serine, Alanine, Proline: Core building blocks of collagen and elastin; hydrate and support skin protein synthesis
  • Histidine (~0.2–0.8%): Moisturizing and skin-protecting; mild antioxidant properties

Sodium PCA & PCA + Sodium Lactate ~0.15–0.70%Proven

Sodium PCA (pyrrolidone carboxylic acid) is one of the most potent naturally occurring humectants in the skin's NMF, capable of attracting and binding up to 250× its weight in water. Sodium lactate (a salt of lactic acid) further reinforces the NMF complex, improving corneocyte hydration and skin softness at the surface.

  • NMF replication: Together these three actives closely mimic the human skin's own moisture-retention chemistry
  • Synergy: Work alongside glycerin and marine extracts for layered humectant action at different skin depths

Salicylic Acid (Trace) <0.1%Preservative Role

Present at a very low concentration — far below the 0.5–2% threshold required for exfoliant action. At this level, salicylic acid functions primarily as a preservative and pH buffer (alongside citric acid), keeping the formula stable at pH 4.0–5.0 rather than acting as a BHA exfoliant.

  • Not an exfoliant at this level: Exfoliant effects of SA require minimum 0.5% concentration in leave-on products
  • Preservative function: Provides mild antimicrobial action to stabilize the aqueous formula
Pregnancy caution: Although trace levels are generally considered safe, pregnant individuals should check with their healthcare provider before use.

33 ingredients · pH 4.0–5.0 · Last verified against official DECIEM INCI listing

Aqua (Water), Glycerin, Algae Extract, Pseudoalteromonas Exopolysaccharides, Pseudoalteromonas Ferment Extract, Ahnfeltia Concinna Extract, Arginine, Glycine, Alanine, Serine, Valine, Isoleucine, Proline, Threonine, Histidine, Phenylalanine, Aspartic Acid, PCA, Sodium PCA, Sodium Lactate, Salicylic Acid, Citric Acid, Propanediol, Dimethyl Isosorbide, Ethoxydiglycol, Polysorbate 20, Potassium Sorbate, Sodium Salicylate, Sodium Benzoate, Hexylene Glycol, 1,2-Hexanediol, Phenoxyethanol, Caprylyl Glycol

FREE FROM: Fragrance / Parfum · Parabens · Silicones · Sulfates · Mineral Oil · Natural Oils · Drying Alcohols (SD Alcohol, Denatured Alcohol) · Hydroquinone · Retinoids · Chemical UV Filters · Dyes & Colorants · Phthalates · Formaldehyde-releasing preservatives
04

Where it fits in your routine

ROUTINE
1
Cleanser
2
Toner / Essence
3
Marine Hyaluronics ★
4
Actives (Vit C / Niacinamide / Retinol)
5
Eye Cream
6
Moisturizer
7
Face Oil (PM)
8
Sunscreen (AM)

Apply 3–5 drops to clean, slightly damp skin before heavier treatments. Damp skin maximizes humectant draw — mist with water or apply immediately after toner for best results. Use AM and/or PM.

05

How to use

HOW TO USE
1

Cleanse Thoroughly

Start with a gentle cleanser suited to your skin type. Marine Hyaluronics should always be applied to clean skin free of makeup, SPF, and sebum so actives can penetrate without barrier.

2

Apply to Damp Skin (Highly Recommended)

For maximum effect, mist your face lightly with water or apply immediately after a watery toner before skin dries. Humectants in this formula work best when there is surface moisture to draw inward. This is especially important in dry-climate environments.

3

Dispense 3–5 Drops

Due to the water-like consistency, tip the dropper bottle and allow 3–5 drops to fall directly into your palm. Do not try to dispense directly to the face — the serum is so fluid it will run off before absorption. Alternatively, tap the pipette directly on your skin in small sections.

4

Pat Gently Across Face & Neck

Press the serum into skin using light patting motions rather than rubbing. Focus on cheeks, forehead, and any areas prone to dryness or tightness. Extend to neck and décolleté if desired. The serum absorbs within seconds.

5

Layer Actives & Seal with Moisturizer

Immediately follow with any actives (vitamin C, niacinamide, retinol) and finish with a moisturizer to occlude and lock in the hydration delivered by Marine Hyaluronics. Without an occlusive layer, humectants can draw moisture out of the skin in very low-humidity environments.

6

Use AM & PM Daily

Safe for twice-daily use. Works equally well in morning (under SPF) and evening routines (alongside retinol or peptides). No conflicts with most actives except The Ordinary's 100% Niacinamide Powder.

06

Who is it for?

WHO

Perfect for you if:

  • You have oily or combination skin and find standard HA serums too tacky
  • You're building a multi-step routine and need a lightweight hydration base
  • Your skin feels tight or dehydrated despite producing oil
  • You use strong actives (retinol, AHAs, vitamin C) and want a buffer hydration layer
  • You're acne-prone and want non-comedogenic hydration
  • You're on a budget and want a clinical-grade hydrating serum under $12
  • You're sensitive to fragrance or essential oils
  • You layer multiple serums and need a serum that won't pill

Consider alternatives if:

  • You have confirmed fungal acne (pityrosporum folliculitis) — contains Polysorbate 20
  • You have severely dry skin that needs rich, oil-based nourishment (this formula is water-only)
  • You live in an extremely arid climate and find humectants pull moisture out of your skin without an occlusive
  • You prefer a thick, viscous serum texture for sensory satisfaction
  • You're pregnant and your OB-GYN advises avoiding all salicylic acid (trace amounts present)
  • You are bothered by the glass dropper bottle being messy to use on the go
07

Skin type compatibility

SKIN TYPES
Oily Skin
Excellent

The ideal skin type for this serum. Oil-free, non-greasy, and absorbs like water without adding any shine or heaviness. Delivers essential hydration to oily skin that is often dehydrated underneath surface sebum.

Combination Skin
Excellent

Outstanding for combination types. The ultra-lightweight texture won't exacerbate T-zone oiliness while providing meaningful hydration to drier cheeks and eye area. Balances well across facial zones.

Dehydrated Skin
Excellent

Specifically formulated for dehydrated skin (any skin type lacking water). The marine water-reservoir complex directly targets surface dehydration, reducing tightness, flakiness, and dullness within days of consistent use.

Sensitive Skin
Good

Fragrance-free, oil-free, and low irritation potential. The trace salicylic acid (preservative-level) is very unlikely to cause sensitivity, but patch test recommended. Not suitable for those with confirmed salicylate allergies.

Acne-Prone Skin
Excellent

Non-comedogenic (1/5 rating), oil-free, and fragrance-free. Addresses dehydration common in acne-prone skin post-actives-use without risking breakouts. Exception: those with fungal acne should avoid due to Polysorbate 20.

Dry Skin
Moderate

Provides surface hydration but this serum alone is insufficient for clinically dry (alipidic) skin. Dry skin types need added emollients and occlusives on top. Use as a first step, followed by a richer moisturizer or face oil to lock in benefits.

08

Results timeline

8–12 WEEKS
First Application

Instant Hydration Surge & Plumpness

Users consistently report that skin feels immediately softer, more supple, and less tight within minutes of application. The marine polysaccharides rapidly form a moisture-film on the skin surface, delivering a perceptible plumping effect from the first use.

~90% noticed immediately
1–2 Weeks Daily Use

Reduced Tightness & Improved Texture

With consistent twice-daily application, surface dehydration lines begin to diminish. Skin texture becomes more even — especially in dry patches around the nose, cheeks, and eye area. The NMF amino acid complex begins to reinforce the skin's own moisture-retention capacity.

~78% reported improved texture
4–6 Weeks

Sustained Plumpness & Improved Glow

By one month of consistent use, cumulative hydration benefits become more apparent: fine dehydration lines are noticeably softened, skin reflects light more evenly (dewy glow), and the skin barrier feels more resilient to environmental stressors. Users of retinol often notice reduced peeling and irritation when Marine Hyaluronics is part of the routine.

~65% reported visible skin improvement
8–12 Weeks

Long-Term Barrier Support & Anti-Aging Hydration

Long-term users (2–3+ months) report that skin maintains a baseline level of hydration throughout the day even without re-application. The amino acid complex supports collagen building blocks over time, contributing to subtle long-term anti-aging benefits beyond immediate hydration.

~62% will repurchase (Deciem Addict survey)
09

Ratings by platform

6K+ REVIEWS
The Ordinary / DECIEM Official
4.3
Rating
1,200+
Reviews
Main complaint: Watery texture is difficult to apply — easy to waste product from the dropper.
Sephora
4.1
Rating
500+
Reviews
Main complaint: Some dry skin users find it insufficient as a standalone hydrator without a rich moisturizer layered on top.
Stylevana
4.4
Rating
300+
Reviews
Main complaint: Subtle results compared to more viscous HA serums; effects build gradually over weeks.
Amazon US
4.2
Rating
4,000+
Reviews
Main complaint: Small 30ml bottle size runs out quickly with twice-daily use (approx. 3–4 months).
Space NK
4.5
Rating
250+
Reviews
Main complaint: Requires a misting step to work best, making it slightly more effort than simply applying a standard serum.
Deciem Addict Community
4.0
Rating
65%
Love It
Main complaint: 35% prefer The Ordinary Hyaluronic Acid 2% + B5 for more visible immediate plumping effect despite tackiness.
10

Pros & cons

BALANCED

Praised

  • Extremely affordable for a 23% active-concentration serum (~$10–11 USD)
  • Zero tackiness or pilling — perfect for layering under makeup and other serums
  • Instant absorption with immediate dewy, plump feel
  • Completely fragrance-free, oil-free, and silicone-free
  • Compatible with virtually all actives — retinol, AHAs, BHAs, vitamin C, niacinamide
  • Sustainably sourced, vegan, and cruelty-free
  • Ideal for oily and combination skin that typical HA serums feel too heavy on
  • Works well under makeup as a non-pilling hydration primer

Criticized

  • Ultra-watery texture is difficult to apply — prone to spilling, dripping, and waste
  • Not fungal-acne safe due to Polysorbate 20 in formula
  • Insufficient as a standalone for clinically dry (alipidic) skin types
  • Results more subtle versus viscous HA formulas for some users
  • Small 30ml bottle is not travel-friendly and runs out quickly
  • Trace salicylic acid may require extra caution during pregnancy
  • Humectant performance reduced in dry-climate environments without a water mist step
11

Budget-friendly alternatives (dupes)

DUPES
75% Match
Hyaluronic Acid Serum
$6.00
Budget Pick

Uses multi-molecular weight hyaluronic acid (sodium hyaluronate and hydrolyzed HA) rather than marine-derived polysaccharides. Slightly more tacky texture but strong humectant performance. No amino acid complex. Larger bottle (60ml) for similar price. FA-safer formula (no Polysorbate 20).

72% Match
Hyaluronic Acid Hydra Power Essence
$15.00
Similar Price

K-beauty essence with sodium hyaluronate and niacinamide in a water-thin texture. Comparable lightweight feel but uses HA rather than marine polysaccharides. Larger 100ml size. Suitable for sensitive skin. Slightly more buildable hydration for dry skin types.

82% Match
Hyaluronic Acid 2% + B5 Serum
$10.90
Same Brand

The Ordinary's own HA serum — the closest sister product. Uses cross-linked, low, medium, and high-molecular-weight hyaluronic acid + vitamin B5. More viscous and slightly tacky texture vs. Marine Hyaluronics. Better choice for dry skin; Marine Hyaluronics wins for oily/combination. Higher pH (6.0–7.5) vs. Marine Hyaluronics (4.0–5.0).

58% Match
Hydro Boost Water Gel
$18.00
Comparable

Uses hyaluronic acid in a gel-serum format. Heavier gel texture, more suitable for dry skin. Contains dimethicone (silicone). Fragrance-free and widely available at drugstores. Does not offer the marine polysaccharide complex or NMF amino acid profile of Marine Hyaluronics.

12

Comparison with competitors

SIDE-BY-SIDE
Key Hydrating Actives Hyaluronic acid (multi-weight) + ceramide + panthenol
Active Concentration Not disclosed
pH 5.5–6.5
Texture Lightweight serum-gel
Fungal Acne Safe No (Ceramide, Fatty Acids)
Fragrance-Free Yes
Vegan & Cruelty-Free Yes
Value ($/ml) $2.20/ml — Very Expensive
Hyalu B5 Eyes Serum
Key Hydrating Actives Hyaluronic acid (2 molecular weights) + Vitamin B5 + Madecassoside
Active Concentration Not disclosed
pH ~5.5–6.0
Texture Light gel-serum, slightly tacky
Fungal Acne Safe Generally Yes
Fragrance-Free Yes
Vegan & Cruelty-Free Cruelty-free (not vegan)
Value ($/ml) $1.30/ml — Expensive
Multi-Molecular Hyaluronic Complex
Key Hydrating Actives 15 forms of HA, HA precursors, hyaluronic acid boosters
Active Concentration High (multi-layered HA system)
pH ~6.0–7.0
Texture Thin serum, slightly more viscous than Marine
Fungal Acne Safe Partially (check INCI)
Fragrance-Free Yes
Vegan & Cruelty-Free Yes (DECIEM brand)
Value ($/ml) $1.07/ml — Moderate
13

Storage & shelf life

12 MONTHS
Period After Opening (PAO)

12 months after opening. The formula contains a multi-preservative system (phenoxyethanol, caprylyl glycol, potassium sorbate, sodium benzoate, sodium salicylate, hexylene glycol, 1,2-hexanediol) that keeps the aqueous formula stable for 12 months once opened.

Storage

Store at room temperature (15–25°C / 59–77°F) in a cool, dry place away from direct sunlight and heat. Do not freeze. The glass dropper bottle should be kept upright to prevent leaking, especially given the extremely fluid consistency.

Packaging

30ml glass dropper bottle with graduated pipette. Glass provides better product stability versus plastic for aqueous formulas. Note: due to the water-like consistency, the pipette can release product rapidly — squeeze gently and allow drops to fall into your palm rather than the pipette tip to face.

Travel Friendly

The 30ml size meets airline carry-on liquid limits (under 100ml). However, the glass bottle and watery formula make it prone to spillage — secure the dropper cap tightly and store upright in a sealed bag when traveling. Consider decanting into a small travel dropper bottle for active travel.

13

Frequently asked questions

FAQ

Marine Hyaluronics is generally considered safe during pregnancy and breastfeeding, as it does not contain retinoids, hydroquinone, or high-dose chemical UV filters. However, the formula does include a trace amount of salicylic acid (used as a preservative/pH adjuster at well below exfoliant concentration). Most dermatologists consider topical salicylic acid at preservative levels safe, but some OB-GYNs prefer to avoid all salicylic acid during pregnancy as a precaution. We recommend confirming with your healthcare provider before use. The marine actives, amino acids, glycerin, and algae extracts are all considered safe in pregnancy.

No. Marine Hyaluronics is NOT considered fungal acne safe. The formula contains Polysorbate 20, an emulsifier that is known to feed Malassezia yeast — the organism responsible for pityrosporum folliculitis (fungal acne). If you have confirmed fungal acne, you should avoid this serum and consider alternatives such as The Ordinary Hyaluronic Acid 2% + B5, which contains a Polysorbate-20-free formula, or Good Molecules Hyaluronic Acid Serum. The trace salicylic acid in the formula is at far too low a concentration to counterbalance the Polysorbate 20 concern.

Yes — Marine Hyaluronics is highly compatible with all of these actives and this is actually one of the serum's biggest strengths. Apply Marine Hyaluronics to clean, damp skin first, allow it to absorb (it absorbs within seconds), then apply your vitamin C, niacinamide, retinol, or AHA/BHA serum on top. For retinol in particular, applying Marine Hyaluronics first as a hydrating base helps buffer dryness and irritation that retinoids can cause. The only product conflict noted by The Ordinary is with their 100% Niacinamide Powder (not standard niacinamide serums).

Marine Hyaluronics is best suited for oily, combination, and dehydrated skin types. Its ultra-lightweight, zero-tacky texture makes it ideal for oily skin that needs hydration without greasiness, and for combination skin where some zones are oily and others are tight or flaky. It works well for any skin type experiencing dehydration (lack of water, distinct from dryness/lack of oil). Sensitive skin types generally tolerate it very well given the fragrance-free, essential-oil-free formula. Those with severely dry (alipidic) skin may find it insufficient as a standalone hydrator and should layer it under a richer moisturizer or oil.

You will notice an immediate effect from the very first application — skin feels softer, more supple, and less tight within minutes. This is due to the marine polysaccharides forming an instant moisture film. For lasting structural changes (reduced dehydration lines, improved overall glow and plumpness), consistent twice-daily use for 2–4 weeks produces visible results that most users notice. After 4–8 weeks, approximately 64% of users in the Deciem community report a visible improvement in skin hydration and appearance. For best results, apply to damp skin and always seal with a moisturizer.

Marine Hyaluronics goes in the early-to-middle treatment step of your routine: after cleansing and toning, and before heavier actives, eye cream, moisturizer, oil, and SPF. The "lightest to heaviest" layering principle places this serum — being water-thin — as one of the very first serums applied. A typical order: Cleanser → Toner → Marine Hyaluronics → Vitamin C or Niacinamide → Retinol (PM) → Moisturizer → Sunscreen (AM). The Ordinary recommends applying it in the "Treat" stage of their morning and evening regimens, specifically before creams and heavier treatments.

No — Marine Hyaluronics has a comedogenic rating of 1/5, making it effectively non-comedogenic. The formula contains no oils, no waxes, and no fatty acids that could clog pores. All primary active ingredients (marine polysaccharides, amino acids, glycerin, PCA, sodium PCA, sodium lactate) score 0/5 on the comedogenic scale. The formula is fully oil-free and has been used successfully by thousands of acne-prone users without triggering breakouts. Note that if you have fungal acne, the Polysorbate 20 may be problematic, but this is a fungal (not bacterial) acne concern, distinct from comedogenicity.

Marine Hyaluronics has a PAO (Period After Opening) of 12 months, meaning the formula remains effective and stable for 12 months once the seal is broken. With twice-daily use of 3–5 drops per application, one 30ml bottle typically lasts 3–4 months — well within the PAO window. If used once daily or with fewer drops, it can stretch to 5–6 months. Store upright at room temperature, away from direct sunlight and heat, to maintain stability. Discard if the product changes color, develops a smell, or its texture changes.

— Skincarisma verdict
4.3 / 5 ★★★★☆

Verdict: The Ordinary Marine Hyaluronics is one of the most intelligently formulated, best-value hydrating serums available anywhere. At under $11 for a 23%-active formula combining Antarctic marine exopolysaccharides, Hawaiian red algae, micro-filtered blue-green algae, and eleven skin-identical NMF amino acids, it delivers a compelling, science-backed alternative to hyaluronic acid — particularly for oily, combination, and dehydrated skin types who find standard HA serums too tacky or heavy. The zero-pilling, water-thin texture makes it uniquely suitable for multi-step routines and actives stacking. The primary drawbacks are the difficult-to-apply watery formula, the Polysorbate 20 that excludes fungal-acne sufferers, and the 30ml bottle that some users find too small. For those without fungal acne concerns, this is a near-essential addition to any skin-type routine at an unbeatable price-to-performance ratio.

Product Overview

question
lightbulb What are Quick Product Notes?

Quick product notes are a great way to check if a product is free from commonly avoided ingredients by skincare enthusiasts. These preferences come about for different reasons depending on the ingredient such as personal experiences, sensitivities, health preferences & etc.

muscle Pro Tip Alert!

Just because a product is not free from a common preference does not mean it's a bad product! You can make a personal decision whether or not you want to use a product that contains these ingredients or not - click the labels of the preference to read more about them.

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Quick Product Notes

Click on icons for more information
question
lightbulb What are Notable Effects & Ingredients?

Ever used a product that promised a certain effect but provided no results? It might not have contained any notable ingredients that could have been responsible for that promised effect. It doesn't matter what the marketing or packaging «promises» it can do, if it doesn't contain anything that can help - then the likelihood of it helping is low.

We help you identify key notable ingredients that have been shown to help with effects such as acne-fighting, brightening, UV-protection, wound healing & anti-aging to help you achieve your skincare goals smarter. Please note that different notable ingredients have varying levels of research behind them, some are extremely well proven yet some have mixed research in their efficacy.

muscle Pro Tip Alert!

Just because a product doesn't contain any notable ingredients doesn't mean it's bad. And a product with notable ingredients (or even many) doesn't necessarily guarantee the efficacy of the product performing these effects either. There are other factors such as ingredient quality, concentration and formulation that will ultimately determine this.

Be smart and use this as just a starting point for you to make more informed and smarter choices and compare it with reviews to see if the product is right for you

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Notable Effects & Ingredients

anti-aging Anti-Aging from 2 ingredient(s):
Histidine Citric Acid
brightening Brightening from 3 ingredient(s):
Glycerin Salicylic Acid Citric Acid
wound Promotes Wound Healing from 5 ingredient(s):
Glycerin Arginine Histidine Phenylalanine Citric Acid
ache Ache-fighting from 1 ingredient(s):
Salicylic Acid
question
lightbulb What are Ingredients Related to Skin Type?

Why are some products great for some people and horrible for others? Well everyone has different skin types and different reactions to the same ingredients.

We've identified a range of ingredients that are commonly regarded as potentially good or bad for those with Dry, Oily/Acne-Prone or Sensitive skin.

muscle Pro Tip Alert!

A product that contains good or bad ingredients for your skin type doesn't always flat out make the entire product good or bad for your skin. There are other factors such as ingredient quality, concentration and formulation that will ultimately determine your skins reaction.

One of the best ways to use this section is to troubleshoot products you've had bad experiences with in the past. Check if it contains any of the marked ingredients to point out suspect ingredients to avoid in the future!

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Ingredients Related to Skin Types

Click on icons for more information
dry-skin Dry Skin
2
oily-skin Oily/Acne-Prone Skin
1 1
sensitive-skin Sensitive Skin
question
lightbulb What is the Ingredient Safety Breakdown?

Ingredient Safety Breakdown refers to the percentage % of ingredients in different risk categories as classified by EWG (Environment Working Group) if they are available. There are almost endless cosmetic ingredients and they are one of the few organisations globally that have assigned ratings to a lot of the more commonly used ingredients which is why we reference them.

muscle Pro Tip Alert!

EWG is seen by many to be more on the alarmist side in their assignment of health ratings resulting in rating ingredients as riskier than they actually are. We recommend using this a reference point rather than a strict guide of ingredient safety and to always do further research if into ingredients that you may find suspect.

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Ingredient Safety Breakdown

EWG Health Ratings
Low risk
Medium risk
High risk
Unknown risk
60% 15% 24%

Product ingredient list

Showing first 5 of 33 ingredients
EWG CIR Ingredient Name & Cosmetic Functions Notes
1 Unknown
Water
Solvent, Skin Conditioning
2 A
Glycerin
Solvent, Perfuming, Fragrance, Humectant, Viscosity Decreasing Agent, Hair Conditioning, Skin Protecting, Denaturant, Skin Conditioning
brightening Brightening
Promotes Wound Healing
Hydrating
1 Unknown
Algae Extract
Skin Conditioning, Emollient, Fragrance, Humectant
0 Unknown
Pseudoalteromonas Exopolysaccharides
Skin Conditioning
1 Unknown
Pseudoalteromonas Ferment Extract
Humectant
VIEW ALL INGREDIENTS