PRODUCT DOSSIER · UNITED STATES MARKET · CAPTURED 31 OCTOBER 2026 · PRICES IN USD
A four-weight hyaluronic acid serum from a French dermatology house, sold by the retailer itself rather than through a marketplace seller, and priced at its own published list without a discount for at least eighteen months. This dossier reads what the formula actually contains against what the listing claims, then sets the reception record and the price record against each other. The most interesting thing in it is not the 4.6-star rating — it is that the box prints ALLERGY TESTED FORMULA WITH FRAGRANCE as a feature.
1. The product
| Brand | La Roche-Posay |
|---|---|
| Product | Hyalu B5 Pure Hyaluronic Acid Anti-Aging Serum for Face |
| Format | Dropper bottle, 30 ml / 1.01 fl oz |
| Declared skin types | All, dry, normal, sensitive |
| Declared scent | Scented |
| Category path | Beauty & Personal Care › Skin Care › Face › Treatments & Masks › Serums |
| Rank at capture | #814 in Beauty & Personal Care · #28 in Facial Serums |
| Seller | Amazon.com — retailer, not a third-party seller |
| Availability | In stock |
1.1 The size attributes contradict each other
Four attributes describe the same bottle. They cannot all be correct, and one of them overstates the fill by a factor of three:
| Attribute | Stated value | What it would mean | Verdict |
|---|---|---|---|
| Unit count | 1.01 fluid ounces | 30 ml — the standard serum size | Correct; corroborated by the stated unit price |
| Item volume | 3.38 fluid ounces | 100 ml — the cream jar size in this range | Wrong by 3.3x |
| Item weight | 0.9 kg | 900 g | Wrong; a 30 ml serum cannot weigh 900 g |
| Shipping weight | 1.98 pounds | ~900 g | Consistent with the error above, not with the product |
This is not a cosmetic defect. A shopper comparing cost per millilitre reads "3.38 fluid ounces" at $39.99 and concludes the price is $11.83 per ounce, when the real figure Amazon itself prints is $39.59 per fluid ounce. The spec table is the one place on a listing where a considered buyer goes for facts, and here it is the least reliable part of the page.
1.2 What the brand claims, with its evidence
| Claim | Number cited | Test design, as stated |
|---|---|---|
| Skin feels smoother instantly | 91% | Consumer test, 85 subjects, twice-daily application |
| Skin barrier repaired | 1 hour | Instrumental test |
| Skin more hydrated and supple | 90% | Consumer test, 85 subjects, twice daily |
| Improved texture | 96% | Consumer test, 85 subjects, twice daily |
| Smoother, firmer, more radiant (GLP-1 users) | 90% | Consumer study, 4 weeks, serum plus cream |
Five of six bullets carry a number with a named test type and sample size, which is rarer than it should be. The last row is the one to handle carefully: its 90% comes from a combined serum-and-cream regimen in people prescribed GLP-1 medication for weight loss, so it cannot be attributed to this bottle alone. It is a legitimate and well-designed claim that has been attached to the wrong unit of sale.
1.3 Gallery
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| Front: cobalt-blue dropper bottle, white carton-style label, "4 Hyaluronic Acid System" mark at the base. Source: Amazon |
Carton front and back. The back panel carries the full INCI, the clinical-efficacy block and the allergy-tested statement with the word "with fragrance". Source: Amazon |
Bottle back label: the complete 32-entry ingredient list, printed in sequence with no omissions. Source: Amazon |
The listing exposes twelve gallery images; the first three are shown. No buyer photographs were available on this capture, so no customer imagery appears in this dossier.
1.4 The routine the brand is actually selling
| Step | Product | Price | Rating | Texture |
|---|---|---|---|---|
| 1 · Cleanse | Purifying Foaming Wash | $19.99 | 4.7 (46,721) | Gentle foaming gel |
| 2 · Treat | Hyalu B5 — this product | $39.99 | 4.6 (36,437) | Rich serum |
| 3 · Moisturise | Hyalu B5 Cream | $27.99 | 4.5 (1,999) | Cream |
| 4 · Protect | Anthelios Ultra SPF 60 | $26.99 | 4.6 (8,612) | Lightweight, sheer |
The serum costs more than the cream that follows it, which is unusual in prestige skincare and tells you where the range's margin sits. It is also the only step described as "rich" — the texture word that, in Section 3, turns out to be doing real formulation work.
2. How it has been received
4.6 out of 5 from 36,437 ratings. This is the second-largest rating base in its category band and one of the highest averages at that volume: a 4.6 sustained across five figures is a materially different claim from a 4.6 across five hundred.
2.1 Star distribution
| Stars | Share | Reading |
|---|---|---|
| 5 star | 81% | Dominant, and dominant by a wide margin |
| 4 star | 9% | Normal shoulder |
| 3 star | 5% | Modest "unremarkable" bucket |
| 2 star | 1% | Below both neighbours — the unusual cell |
| 1 star | 4% | Four times the two-star bucket |
The 2% dip is the analytical detail worth having. In a normal distribution of disappointment you expect 1 star < 2 star < 3 star. Here 2 star sits below 1 star, which means dissatisfaction is binary rather than graduated: buyers either find the product unremarkable (three stars) or they have a specific bad reaction (one star). There is very little "it was a bit disappointing" in between. Section 2.3 names what the specific bad reaction is.
2.2 What buyers argue about
| Theme | Mentions | Positive share | Position |
|---|---|---|---|
| Moisturising | 692 | 90% | Strongest signal on the page |
| Skin appearance | 279 | 90% | Glow and plumpness |
| Effectiveness | 1,139 | 84% | Largest theme, settled positive |
| Texture | 492 | 74% | Positive with a real minority dissent |
| Duration | 88 | 70% | Small sample |
| Value for money | 299 | 55% | Split — the price is contested |
| Skin compatibility | 212 | 55% | Split — this is the sensitive-skin question |
| Fragrance | 446 | 46% | Weakest theme; near-even split |
Four themes at 74% or above describe the product's actual job and they are not in dispute: it hydrates, it makes skin look better, it works, and the texture pleases most people. The two soft spots — fragrance at 46% and compatibility at 55% — are the same issue seen twice, because this is a scented serum sold to sensitive skin and 446 people wrote about the scent to a near-even split.
2.3 The summary, in the marketplace's own words
Customers find the serum effective and notice visible results, with their skin feeling deeply hydrated and soft. Moreover, the product gives a glowing look and lasts throughout the day. However, opinions are mixed regarding fragrance, with some finding it lovely while others describe it as very strong perfume. Additionally, skin compatibility receives mixed feedback — while some find it gentle enough for most skin types, others report it irritated their skin. Value for money opinions are also divided, with some considering it well worth the cost while others warn not to waste money on it.
Note what this abstract does not resolve. It reports that buyers disagree about whether a fragrance-forward serum suits sensitive skin, and it stops there — which is the honest position, because the disagreement is real and the underlying formula (Section 3) explains both sides.
2.4 What could not be collected
Review text and buyer photographs did not render. Three escalating fallbacks were attempted after the initial fetch — a mobile render, a non-US context render, and a retry sequence with fresh sessions. No review body appeared and the buyer-photo carousel reported zero image tiles. This dossier therefore quotes no reviewer and shows no customer imagery. The rating, distribution and theme tally above are unaffected, and no buyer language has been reconstructed from the summary.
3. What is actually in the bottle
The pack prints 32 ingredients. That number matters before anything else, because the most widely mirrored third-party ingredient table for this product lists only 22 of them — and the ten-row gap includes three ingredients that do real work.
3.1 The official list, as printed on the pack
Expand the complete 32-entry INCI (F.I.L. code T70066625/1)
| # | Ingredient | What it is doing here |
|---|---|---|
| 1 | Aqua / Water / Eau | Base |
| 2 | Glycerin | Primary humectant |
| 3 | Alcohol Denat. | Thins a rich formula, accelerates dry-down |
| 4 | Propylene Glycol | Humectant and penetration enhancer |
| 5 | Panthenol | Vitamin B5 — soothing humectant, the named active |
| 6 | Pentylene Glycol | Humectant, preservative booster |
| 7 | Dimethicone | Silicone — the "rich" feel |
| 8 | PEG-6 Caprylic/Capric Glycerides | Solubiliser |
| 9 | Alpinia Galanga Leaf Extract | Botanical, antioxidant support |
| 10 | Calcium Chloride | Electrolyte, texture control |
| 11 | Glyceryl Isostearate | Emollient ester — the fungal-acne flag |
| 12 | Madecassoside | Purified centella fraction, soothing |
| 13 | PPG-6-Decyltetradeceth-30 | Emulsifier |
| 14 | Sodium Acetylated Hyaluronate | Hyaluronic species two of four |
| 15 | Sodium Hyaluronate | Hyaluronic species three of four |
| 16 | Algin | Algal thickener |
| 17 | Adenosine | Anti-wrinkle active |
| 18 | Ammonium Polyacryloyldimethyl Taurate | Emulsion stabiliser |
| 19 | Propanediol | Humectant and solvent |
| 20 | Hydrolyzed Hyaluronic Acid | Hyaluronic species four of four (low weight) |
| 21 | Hydroxyacetophenone | Antioxidant preservative booster |
| 22 | Caprylic/Capric Triglyceride | Emollient |
| 23 | Caprylyl Glycol | Humectant preservative booster |
| 24 | Citric Acid | pH buffer |
| 25 | Trisodium Ethylenediamine Disuccinate | Chelator |
| 26 | Acetyl Glucosamine | Brightening and barrier precursor |
| 27 | Xanthan Gum | Thickener |
| 28 | Butylene Glycol | Humectant |
| 29 | 1,2-Hexanediol | Solvent, preservative booster |
| 30 | Tocopherol | Vitamin E, antioxidant |
| 31 | Phenoxyethanol | Preservative |
| 32 | Parfum / Fragrance | Fragrance — declared, not incidental |
3.2 The four-weight claim, checked
| Claim element | What the INCI supports |
|---|---|
| High-weight HA | Sodium hyaluronate (position 15) — the high molecular weight form |
| Encapsulated HA + vitamin B5 | Not separately declarable; panthenol is present at position 5. Encapsulation is a process, not an ingredient, so it leaves no INCI trace |
| Low and micro weight HA | Hydrolyzed hyaluronic acid (position 20) and sodium acetylated hyaluronate (position 14) |
So the pack supports three named hyaluronic species plus panthenol, which is a fair reading of "4 Hyaluronic Acid System" if the fourth element is the vitamin B5 partner rather than a fourth HA molecule. The claim is defensible and it is also not four hyaluronic acids. Anyone repeating "four weights of hyaluronic acid" is repeating marketing shorthand.
3.3 Ingredient roles, counted
The largest group is humectants and solvents — ten of thirty-two, a third of the formula — which is exactly what a hydration product should look like. But the third line of the list is where the story is.
3.4 Position 3
Alcohol Denat. sits at position 3 of 32 — ahead of every humectant except glycerin, ahead of the panthenol the product is named after, and ahead of all four hyaluronic species. In EU labelling, position reflects concentration, so this is a formula in which denatured alcohol is the third most abundant ingredient.
Its job is real and it is not a cost shortcut: a serum carrying dimethicone plus caprylic/capric triglyceride would otherwise feel heavy on the skin, and alcohol is what makes a "rich serum" dry down quickly. The trade is texture against tolerance. It is also why the box says CAUTION: FLAMMABLE UNTIL DRY — a warning that appears on very few facial serums and is a direct consequence of this one line of the INCI.
3.5 The claim matrix
| Claim | Holds | Evidence |
|---|---|---|
| EU-allergen-free | Yes | No individually declarable allergen among the 32 entries |
| Oil-free | Yes | No oil-phase ingredient; the emollients are esters and a silicone |
| Paraben-free | Yes | Preservation is phenoxyethanol, caprylyl glycol, hydroxyacetophenone, 1,2-hexanediol |
| Sulfate-free | Yes | No sulfate surfactant present |
| Pore-clogger-free | Yes | Nothing on the tracked trigger list |
| Reef-safe | Yes | Nothing on the tracked restriction list |
| Fragrance-free | No | Parfum at position 32 — and the carton states "allergy tested formula with fragrance" |
| Alcohol-free | No | Alcohol Denat. at position 3 |
| Silicone-free | No | Dimethicone at position 7 |
| Vegan | No | Brand-level status |
| Cruelty-free | No | Brand-level status |
| Fungal-acne-safe | No | Glyceryl Isostearate at position 11 — an ester on the trigger list |
Six pass and six fail. The fragrance failure is the most interesting, because this brand did not hide it: the carton prints ALLERGY TESTED FORMULA WITH FRAGRANCE in a highlighted band, and the marker line reads TESTED ON SENSITIVE SKIN directly beneath it. That is a deliberate positioning decision — the scent is treated as part of the product experience, and the allergy testing is offered as the mitigation. Whether that is acceptable is a genuine judgement call, and the 46%-positive fragrance theme is what that judgement call looks like in aggregate.
3.6 Grading, and how thin it is
| Grading status | Ingredients | How to read it |
|---|---|---|
| Graded 0 comedogenic / 0 irritant | 4 — glycerin, propylene glycol, panthenol, sodium hyaluronate | No known risk on either scale |
| Graded 1 comedogenic / 0 irritant | 2 — dimethicone, butylene glycol | Lowest non-zero grade; note that the listing claims non-comedogenic, which is a claim about the finished product |
| Range-rated 0–3 | 1 — tocopherol | Sources disagree; judged at the upper bound |
| No grade at all | 25 | Missing data — not a clean bill of health |
Twenty-five of thirty-two ingredients carry no grade. The alcohol at position 3 is one of them. The parfum is another. So the two entries most likely to cause a reaction in a sensitive-skin buyer are precisely the two the grading system does not score, and the risk signal for this formula has to come from the class-level concerns below rather than from a per-ingredient table.
3.7 Concerns
| Concern | Ingredients implicated | What it describes |
|---|---|---|
| May worsen eczema | 3 | Increased itching or irritation on eczema-prone skin |
| May worsen rosacea | 3 | Flare-ups in rosacea-prone skin |
| May worsen dryness | 1 | Can strip moisture |
| May worsen irritation | 1 | Stinging, redness or sensitivity |
The counts are the message. Eczema and rosacea implicate three ingredients each — alcohol denat., parfum and the citric acid buffer — while dryness and irritation implicate one. The database is saying this formula is more likely to be a problem for barrier-disordered or reactive skin than to be drying in itself. That is consistent with a rich hydrator built on glycerin, panthenol and three hyaluronic species. It is also the exact opposite of what a shopper buying "for sensitive skin" expects to find.
3.8 The count check, and why it changes the benefit reading
The most useful byproduct of reading the pack label is a discrepancy check. The widely mirrored third-party table for this product lists 22 of the 32 official entries:
| Check | Result |
|---|---|
| Official INCI count (pack label) | 32 |
| Third-party table count | 22 |
| Entries absent from the table | 11 |
| Entries in the table but not on the pack | 1 — "Disodium EDTA", where the pack prints trisodium ethylenediamine disuccinate |
The eleven absent entries are: Alpinia Galanga Leaf Extract, Calcium Chloride, Sodium Acetylated Hyaluronate, Algin, Adenosine, Propanediol, Hydroxyacetophenone, Caprylic/Capric Triglyceride, Trisodium Ethylenediamine Disuccinate, Acetyl Glucosamine and 1,2-Hexanediol.
Three of those are functional rather than incidental, and each one shifts a conclusion:
- Sodium acetylated hyaluronate is one of the four hyaluronic species the product is sold on. A table without it understates the headline claim.
- Adenosine is an anti-wrinkle active. Its absence is why the "anti-ageing" benefit below shows only four supporting ingredients.
- Acetyl glucosamine is a brightening and barrier precursor. Its absence is why "brightening" shows up with a single ingredient, which is not a fair reading of this formula.
So benefit counts derived from the 22-row table are lower bounds, not properties of the product. That caveat is carried into the next chart rather than quietly dropped.
3.9 Benefits, weighted
| Benefit | Ingredients (from the 22-row table) | Adjustment from the full INCI |
|---|---|---|
| Hydrating | 7 | Higher — propanediol and 1,2-hexanediol are also humectants |
| Barrier repair | 7 | Higher — acetyl glucosamine contributes |
| Scar healing | 5 | Unchanged |
| Anti-ageing | 4 | Higher — adenosine is missing from the count |
| Redness reducing | 4 | Unchanged |
| Reduces irritation | 2 | Unchanged |
| Brightening | 1 | Materially understated — acetyl glucosamine is absent |
| Dark spots | 1 | Materially understated for the same reason |
| Skin texture | 1 | Unchanged |
Seven ingredients behind hydration and seven behind barrier repair is the strongest benefit profile in this batch, and the full INCI makes it stronger, not weaker. The formula is not a bare hyaluronic serum with two actives bolted on — it is a thirty-two-entry formulation in which hydration, barrier support and soothing are each carried by a genuine group of ingredients.
4. Price
| Current price | $39.99 |
|---|---|
| List price | $39.99 — current matches list exactly |
| Discount or coupon | None |
| Subscribe & save | $37.99 — a 5% step, not the 10% this programme usually gives |
| Unit price | $39.59 per fluid ounce |
| Delivery | Free over $35; Prime next-day offered |
The 5% subscribe step is worth pausing on. On a $39.99 item that is $2.00, which is thin enough to be almost invisible, and it is the only price incentive on the page — no list-price discount, no coupon, no multipack. For a product selling 36,437 ratings' worth of volume, the absence of any discount architecture is a deliberate choice, and the price record below shows how deliberate.
4.1 The price record
| Channel | Lowest ever | Highest ever | Current | Average |
|---|---|---|---|---|
| Amazon retail | $17.99 (22 Jan 2021) | $39.99 (25 Apr 2025) | $39.99 (29 Oct 2026) | $39.48 |
| Third-party new | $27.97 (6 Oct 2026) | $39.99 (4 Oct 2026) | $39.99 (30 Oct 2026) | $35.51 |
| Third-party used | No data at any point since monitoring began in March 2018 — this product has no secondary market | |||
Dated observations only. The tracker publishes five values per channel rather than a daily series, so nothing is interpolated between points.
4.2 What the record actually says
1. The average is misleading, and in a specific direction. The $39.48 all-time average sits 1.3% under today's price, which reads as "normal". It is not a normal average: it is a mean computed across a series that moved once, in April 2025, and has not moved since. Eighteen months of a fixed price plus a cheaper earlier era produces a number that describes neither period.
2. The spread measures one event, not volatility. A 122% high-to-low spread looks dramatic. The low is January 2021, the high is April 2025, and the price has held the high ever since. This is a repricing, not a market that moves.
3. The third-party range is 48 hours wide. Its all-time high is 4 October 2026 and its all-time low is 6 October 2026 — two days apart, twelve days before capture. Whatever happened there, it happened once and it reverted. The record cannot distinguish a promotional episode from a brief competitive entrant, and no claim is made about which.
4. Parity is total, and that is the finding. Both channels sit at $39.99, which equals the published list. With Amazon itself in the buy box, this is a manufacturer-controlled price point rather than a competitive one. Nothing on this page is competing on price, and the 5% subscribe step is the only lever the brand has left itself.
4.3 Position summary
| Benchmark | Amazon versus benchmark | Third-party versus benchmark |
|---|---|---|
| All-time low | +122.3% | +43.0% |
| All-time high | 0.0% — today is the high | 0.0% — today is the high |
| All-time average | +1.3% | +12.6% |
| List price | 0.0% | 0.0% |
5. Verdict
| Question | Answer | Confidence |
|---|---|---|
| Does it do what it is sold to do? | Yes. Hydration at 90% positive across 692 mentions, appearance at 90%, effectiveness at 84% across 1,139 | High |
| Is the four-weight hyaluronic claim true? | Three named HA species plus panthenol; defensible as a system, not as four hyaluronic acids | Medium-high |
| Is it right for sensitive skin? | Contested by design — alcohol at position 3 and declared parfum, with the brand selling the allergy testing as mitigation | Medium |
| Is the ingredient record trustworthy? | The pack is; the common third-party table is not — it omits 11 of 32 entries | High on the pack, low on the table |
| Is the price competitive? | It is not competing. Both channels sit at list, with a 5% subscribe step as the only incentive | High |
| Is the listing accurate? | No on size — three of four size attributes are wrong, one by a factor of 3.3 | High |
| Are buyer voices represented? | Only in aggregate; no review text or photography rendered | Low |
6. Method and limits
Method. One capture on 31 October 2026 with the delivery address set to a United States ZIP code before any price was read and the currency pinned to US dollars. All prices are native USD; none converted, estimated or given as a range. Gallery images downloaded at 1500 pixels, and the pack label was read from the gallery imagery at full resolution rather than from any secondary summary. Rating, star distribution and theme tally come from the same capture. No reviewer name, handle, identifier or profile link was collected, and none appears here. Ingredient grading is community-database reference material, not a regulatory or dermatological finding.
| Element | Confidence | Basis |
|---|---|---|
| Price and currency | High | US delivery context verified; USD price present; buy box at $39.99 on the capture date |
| Rating and distribution | High | Rendered directly |
| Official INCI (32 entries) | High | Read from the pack label in the gallery imagery |
| Claim statistics | High | Published with test type and sample size |
| Theme tally | Medium-high | Marketplace aggregate; rounding not disclosed |
| Per-ingredient grading | Low | 7 of 32 entries graded; 25 ungraded |
| Benefit counts | Medium | Derived from a 22-row table that omits 11 entries — lower bounds only |
| Price statistics | High for values | Current observations one to two days old at capture |
| Buyer reviews and photos | None collected | Did not render; not reconstructed |
- Review bodies and buyer photographs did not render; no verbatim buyer language appears.
- Three of four size attributes contradict each other; the 1.01 fl oz figure was adopted because the stated unit price corroborates it.
- Per-ingredient grades cover 7 of 32 entries; 25 are ungraded, and ungraded is not zero.
- Benefit counts come from a 22-row table that omits 11 official entries and are reported as lower bounds.
- The third-party price range compresses into 48 hours twelve days before capture; its cause cannot be established from the record.
- Price statistics are all-time by nature of the source; no period-specific figure exists in this record.
- Sales rank is a single observation and moves between captures.
Captured 31 October 2026 with a United States delivery context. Prices in US dollars, unconverted. Treat every figure as an observation of that date.