Hyaluronic Acid for Skin: Hydration, Wrinkles and Aging

Table of Contents

1. 1. How Hyaluronic Acid Holds Water in the Skin
2. 2. How Much of the Body’s Hyaluronan Sits in the Skin
3. 3. What Happens to Skin Hyaluronan With Age
4. 4. Oral Hyaluronic Acid Trials: Wrinkles and Moisture
5. 5. The 2025 Meta-Analysis of Oral Hyaluronic Acid
6. 6. Does Swallowed Hyaluronic Acid Reach the Skin?
7. 7. Molecular Weight in Creams and Serums
8. 8. Injected Hyaluronic Acid and Skin Quality
9. 9. Reported Side Effects of Fillers and Skin Products
10. 10. Gaps and Limits in the Skin Research
11. Key Research Papers
12. Connections

1. How Hyaluronic Acid Holds Water in the Skin

Hyaluronic acid is a long, unbranched chain made of one repeating pair of sugars: D-glucuronic acid and N-acetyl-D-glucosamine, joined over and over again. A single chain can be enormous — reviews describe chains reaching millions of daltons, far larger than most molecules in the body. Unlike its chemical cousins chondroitin sulfate and heparin, it carries no sulfate groups and is not attached to a protein core; cells spin it out directly at the inner face of their outer membrane.

Each glucuronic acid unit carries an acid group, which is why the molecule is called an acid and why it is often sold as its sodium salt. A long chain packed with these groups attracts and binds water around itself. Laurent and colleagues described how hyaluronan chains tangle into networks even at very dilute concentrations (under 1 mg per mL), which gives hyaluronan solutions their unusual thick, slippery flow. In skin, that tangled, water-swollen network fills the space between cells and fibres.

A 2012 review by Papakonstantinou, Roth and Karakiulakis calls hyaluronic acid “a key molecule in skin aging” and the main molecule involved in skin moisture, while stressing that its making and breaking in skin are complex and tightly regulated. It works alongside collagen and elastin rather than replacing them: collagen gives the skin its strength, and hyaluronan holds the water that keeps that framework plump.

The body makes its own

The natural source of skin hyaluronan is the skin itself. Three enzymes, the hyaluronan synthases HAS1, HAS2 and HAS3, build the chain from two activated sugars (UDP-glucuronic acid and UDP-N-acetylglucosamine) that cells make from glucose. In laboratory studies HAS2 made the very largest chains, while HAS3 made shorter ones. The amino sugar in hyaluronan is the same family of molecule described on the site’s Glucosamine page.

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2. How Much of the Body’s Hyaluronan Sits in the Skin

Hyaluronan is found in every vertebrate tissue and body fluid, and is especially abundant in loose connective tissue. Reviews state that an adult weighing 70 kg carries about 15 g of it, and Stern estimated that about 5 g of that is broken down and replaced every day — a remarkably fast turnover for a structural material.

The skin holds the largest share. The 2018 review by Fallacara and colleagues states that approximately half of all the body’s hyaluronic acid resides in the skin. That figure was measured directly in rats: Reed, Lilja and Laurent found in 1988 that more than half of a rat’s total hyaluronan was in its skin, about a quarter in the skeleton and supporting tissues, and less than a tenth in muscle. They also estimated that the hyaluronan naturally present in rat skin, once corrected for breakdown during extraction, had a molecular weight of several million.

Skin hyaluronan does not sit still. One review estimates its half-life in skin at about 24 hours, compared with one to three weeks in cartilage and around 70 days in the vitreous of the eye. That estimate is the review’s citation of earlier work rather than a fresh measurement, but it fits the broader picture of a molecule that the skin is constantly making, breaking down and remaking. Old chains are taken up through the CD44 receptor and cut into smaller and smaller pieces by hyaluronidase enzymes, and the pieces are recycled inside the cell.

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3. What Happens to Skin Hyaluronan With Age

It is often said that skin “loses its hyaluronic acid” with age. The evidence is more interesting than that.

In 1994, Lawrence Meyer and Robert Stern measured hyaluronan in human skin taken at autopsy from people of many ages, from fetal skin to old age. They found no significant change with age in the total concentration of hyaluronan or in the size of its chains. What did change was how the hyaluronan was held. A fraction that could be freed only by digesting the tissue with the enzyme papain — hyaluronan tightly bound into the tissue — rose from about 7% in fetal skin to about 23% in elderly skin, and the location of the hyaluronan within the skin shifted. In other words, older skin in that study had about as much hyaluronan, but more of it was locked away and less of it was free to bind water.

Later reviews, including the 2012 Papakonstantinou review, describe a decline of skin hyaluronan with age, and the authors of a 2023 oral trial wrote that skin hyaluronic acid “decreases significantly with age.” No verified source gives a single reliable figure for how much is lost, so this page does not quote one. Both findings are reported here: older autopsy measurements found the amount stable but the binding changed, while newer reviews describe a decline.

Hyaluronan is only one part of the skin’s structure, so changes in it are one strand of skin aging alongside changes in collagen and elastin (see the site’s Collagen for Skin Elasticity page) and the effects of sunlight covered on the UV Radiation page.

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4. Oral Hyaluronic Acid Trials: Wrinkles and Moisture

Several double-blind, placebo-controlled trials have tested hyaluronic acid swallowed as a capsule or drink and measured the skin with instruments rather than by impression alone. The main ones are summarised below.

• Oe and colleagues, 2017. 60 adults took 120 mg/day of hyaluronic acid of either 2 kDa (very small) or 300 kDa (medium) size, or placebo, for 12 weeks. The 300 kDa group had fewer wrinkles than the placebo group at 8 weeks.
• Hsu and colleagues, 2021. 40 adults took 120 mg/day of hyaluronic acid or placebo for 12 weeks. Wrinkles, water content of the outer skin layer, water loss through the skin and elasticity all improved compared with placebo.
• Gao and colleagues, 2023. 129 women took oral hyaluronic acid or placebo. Skin hydration improved from 2 to 8 weeks, skin tone from 4 to 8 weeks, and the thickness of the outer skin layer by 12 weeks.

The Oe 2017 trial is of particular interest because it compared two sizes of molecule directly. Both forms showed better wrinkle measures than placebo over the study, but only the medium-sized (300 kDa) form reached statistical significance against placebo at the 8-week point; the authors concluded that both forms inhibited wrinkles. Chain size comes up again and again in hyaluronan research, because large and small pieces behave differently in the body (see section 7).

These trials were small and lasted no longer than three months. Several share authors with a 2016 review of oral hyaluronan for knee pain written by researchers connected to a hyaluronic acid manufacturer (Oe and colleagues, 2016). Industry funding is common in supplement research and does not by itself make a result wrong, but independent replication is the usual test, and few independent trials exist yet.

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5. The 2025 Meta-Analysis of Oral Hyaluronic Acid

In 2025, Amin and colleagues pooled seven randomised controlled trials of oral hyaluronic acid for skin in a meta-analysis published in the Journal of Drugs in Dermatology. Pooling trials gives a better sense of the overall effect than any single small study.

What improved

• Skin hydration — a statistically significant improvement over placebo.
• Skin elasticity — significant improvement.
• Wrinkle depth — significant reduction.

What did not

• Skin firmness — no significant difference.
• Wrinkle volume — no significant difference.
• Transepidermal water loss (how fast water escapes through the skin) — no significant difference when trials were pooled.

That last result is worth noting, because the single Hsu 2021 trial did report less water loss. A finding that appears in one trial but not in the pooled data is a reason for caution. The authors themselves pointed to the small sample sizes and the differences between trials as limits.

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6. Does Swallowed Hyaluronic Acid Reach the Skin?

A natural question is how a large molecule swallowed in a capsule could reach the skin at all. The answer from animal research is disputed. Kimura and colleagues, writing in 2016, summed it up in their own words: “the absorption of orally administrated HA remains controversial.” No human study tracing swallowed hyaluronan into the skin was found for this page.

Studies suggesting it does

• Rats, labelled carbon (Oe and colleagues, 2014). About 90% of the radioactive label was absorbed from the gut; the amount in the skin was higher than in the blood at 24 and 96 hours. Because the label follows the carbon atoms, part of what reached the skin may have been breakdown products rather than intact hyaluronan.
• Rats, mechanism (Kimura and colleagues, 2016). Hyaluronan survived artificial stomach and small-intestine juices but was broken down by gut bacteria in the caecum into short pieces (oligosaccharides), which passed through the wall of the large intestine. After oral 300 kDa hyaluronan, short and long pieces were found in the skin.
• Rats and dogs (Balogh and colleagues, 2008). Most of a radioactively tagged high-molecular-weight dose came out in the faeces, yet radioactivity appeared in tissues from 15 minutes to 48 hours, concentrated in joints, vertebrae and salivary glands, and imaging showed it taken up into skin, bone and joints.

A study suggesting it does not

• Rats (Laznicek and colleagues, 2012). After oral hyaluronan tagged in two different ways, the authors found no significant absorption into the bloodstream with one tag and only traces with the other.

One possible way to fit these together, offered by the Kimura group, is that gut bacteria break hyaluronan into small pieces that can be absorbed, so what reaches the body is mainly fragments rather than the original long chain. Whether that is what drives the skin results in human trials has not been shown.

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7. Molecular Weight in Creams and Serums

Creams, lotions and serums are the most familiar way hyaluronic acid meets the skin. A large molecule spread on the surface tends to stay on the surface, holding water there like a film; smaller pieces are often described as moving further in. Product labels frequently advertise “low” or “multi” molecular weight for this reason.

A 2024 double-blind randomised trial by Muhammad and colleagues tested this directly in 36 elderly people with xerosis cutis (dry, rough skin, common in old age). They compared a low-molecular-weight hyaluronic acid lotion, a high-molecular-weight hyaluronic acid lotion and the same lotion without hyaluronic acid. After 4 weeks:

• The low-molecular-weight lotion gave higher skin capacitance (a measure of surface hydration) than either the high-molecular-weight lotion or the plain lotion.
• There was no difference between the groups in water loss through the skin.
• No side effects were recorded in any group.

Why size matters in the body

Size does more than change how deep a molecule goes. Reviews by Stern and colleagues describe large hyaluronan polymers as space-filling and calming to the immune system, while small fragments can act as “danger signals” that switch on inflammation and the growth of new blood vessels. Small fragments are produced naturally whenever tissue is injured. This is one reason researchers study molecular size so closely, and it reappears in the safety findings for fillers below.

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8. Injected Hyaluronic Acid and Skin Quality

Hyaluronic acid is also injected into the skin. The best-known use is the dermal filler: a gel of hyaluronic acid, usually chemically cross-linked so that it lasts longer, injected to fill lines or add volume. A second use places small amounts of hyaluronic acid throughout an area to improve overall skin quality rather than to fill a single line.

A 2025 systematic review and meta-analysis by Zhou and Yu pooled six studies of locally injected hyaluronic acid and skin aging. It reported:

• Skin hydration improved, with a large pooled effect (standardised mean difference 1.34).
• Skin radiance improved, with a moderate effect (standardised mean difference 0.51).
• Skin elasticity did not improve significantly.
• Melanin index (a measure of pigmentation) did not change significantly.

So in this pooled analysis, injected hyaluronic acid made skin measurably wetter and brighter, but did not make it springier or change its pigment. Injections are a medical procedure, and their side effects are covered in the next section.

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9. Reported Side Effects of Fillers and Skin Products

Dermal fillers: the trial evidence

Kyriazidis and colleagues reviewed 48 randomised controlled trials of hyaluronic acid fillers for the face, published in 2024. Most side effects were short-lived reactions at the injection site. Severe events — including severe swelling and angioedema — were rare but needed treatment. The enzyme hyaluronidase, which breaks hyaluronic acid down, was among the treatments used.

Late-onset reactions

Some reactions appear well after the injection. A 2024 expert consensus led by Baranska-Rybak described late-onset reactions to hyaluronic acid fillers that typically appear three to four months after injection, though sometimes from as early as 24 hours. The panel proposed three possible causes: low-molecular-weight hyaluronic acid present in the product (in line with the “danger signal” behaviour of small fragments described in section 7), infection or a bacterial biofilm on the gel, and an imbalance in the person’s immune response. This is an expert opinion document rather than trial data.

Creams and oral forms

In the 2024 elderly dry-skin trial, no side effects were recorded with either hyaluronic acid lotion. The oral skin trials summarised in section 4 did not report safety problems in their published abstracts. That is not the same as a proof of safety: the trials were small and short, and no independent review dedicated to the long-term safety of oral hyaluronic acid was found for this page.

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10. Gaps and Limits in the Skin Research

• Small, short trials. The oral trials enrolled between 40 and 129 people and ran for 12 weeks at most. The 2025 meta-analysis rests on seven of them.
• Industry links. Several oral trials share authors with researchers connected to a hyaluronic acid manufacturer. Independent replication is limited.
• Absorption is unsettled. The animal studies disagree on whether swallowed hyaluronan is absorbed, and no human tracing study was found.
• Age decline is contested. A careful autopsy study found the amount of skin hyaluronan stable with age but its binding changed; later reviews describe a decline. No reliable figure for the loss exists in the verified sources.
• Molecular size varies between products. Trials used different sizes (2 kDa, 300 kDa, “low” and “high” molecular weight), so results from one form do not automatically apply to another.
• Food sources. Animal connective tissues such as rooster comb are traditional sources from which hyaluronic acid is extracted, and chicken-vegetable bone broth contains hyaluronan together with chondroitin sulfate. No verified source gives the hyaluronan content of any food, and no verified study shows a food raising skin hyaluronan in people. The body builds its own from glucose-derived sugars; vitamin C’s well-known role in skin is in making collagen, not hyaluronan (see Vitamin C for Collagen Synthesis).
• Outcomes measured. Instrument readings such as skin capacitance and wrinkle depth are useful, but the trials measured them over weeks; whether the changes last after stopping has not been studied in the verified trials.

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Key Research Papers

1. Papakonstantinou E, Roth M, Karakiulakis G. Hyaluronic acid: A key molecule in skin aging. Dermatoendocrinol. 2012;4(3):253-8. PubMed PMID: 23467280
2. Meyer LJ, Stern R. Age-dependent changes of hyaluronan in human skin. J Invest Dermatol. 1994;102(3):385-9. PubMed PMID: 8120424
3. Reed RK, Lilja K, Laurent TC. Hyaluronan in the rat with special reference to the skin. Acta Physiol Scand. 1988;134(3):405-11. PubMed PMID: 3227957
4. Fallacara A, Baldini E, Manfredini S, Vertuani S. Hyaluronic Acid in the Third Millennium. Polymers (Basel). 2018;10(7):701. PubMed PMID: 30960626
5. Laurent TC, Laurent UB, Fraser JR. The structure and function of hyaluronan: An overview. Immunol Cell Biol. 1996;74(2):A1-7. PubMed PMID: 8724014
6. Stern R. Hyaluronan catabolism: a new metabolic pathway. Eur J Cell Biol. 2004;83(7):317-25. PubMed PMID: 15503855
7. Stern R, Asari AA, Sugahara KN. Hyaluronan fragments: an information-rich system. Eur J Cell Biol. 2006;85(8):699-715. PubMed PMID: 16822580
8. Itano N, Sawai T, Yoshida M, Lenas P, Yamada Y, Imagawa M, Shinomura T, Hamaguchi M, Yoshida Y, Ohnuki Y, Miyauchi S, Spicer AP, McDonald JA, Kimata K. Three isoforms of mammalian hyaluronan synthases have distinct enzymatic properties. J Biol Chem. 1999;274(35):25085-92. PubMed PMID: 10455188
9. Oe M, Sakai S, Yoshida H, Okado N, Kaneda H, Masuda Y, Urushibata O. Oral hyaluronan relieves wrinkles: a double-blinded, placebo-controlled study over a 12-week period. Clin Cosmet Investig Dermatol. 2017;10:267-273. PubMed PMID: 28761365
10. Hsu TF, Su ZR, Hsieh YH, Wang MF, Oe M, Matsuoka R, Masuda Y. Oral Hyaluronan Relieves Wrinkles and Improves Dry Skin: A 12-Week Double-Blinded, Placebo-Controlled Study. Nutrients. 2021;13(7):2220. PubMed PMID: 34203487
11. Gao YR, Wang RP, Zhang L, Fan Y, Luan J, Liu Z, Yuan C. Oral administration of hyaluronic acid to improve skin conditions via a randomized double-blind clinical test. Skin Res Technol. 2023;29(11):e13531. PubMed PMID: 38009035
12. Amin P, Sarabi A, Choe S, Scott S, Suh S, Mesinkovska NA. Oral Hyaluronic Acid Supplement: Efficacy in Skin Hydration, Elasticity, and Wrinkle Depth Reduction. J Drugs Dermatol. 2025;24(9):910-919. PubMed PMID: 40911749
13. Oe M, Tashiro T, Yoshida H, Nishiyama H, Masuda Y, Maruyama K, Koikeda T, Maruya R, Fukui N. Oral hyaluronan relieves knee pain: a review. Nutr J. 2016;15:11. PubMed PMID: 26818459
14. Oe M, Mitsugi K, Odanaka W, Yoshida H, Matsuoka R, Seino S, Kanemitsu T, Masuda Y. Dietary hyaluronic acid migrates into the skin of rats. ScientificWorldJournal. 2014;2014:378024. PubMed PMID: 25383371
15. Kimura M, Maeshima T, Kubota T, Kurihara H, Masuda Y, Nomura Y. Absorption of Orally Administered Hyaluronan. J Med Food. 2016;19(12):1172-1179. PubMed PMID: 27982756
16. Balogh L, Polyak A, Mathe D, Kiraly R, Thuroczy J, Terez M, Janoki G, Ting Y, Bucci LR, Schauss AG. Absorption, uptake and tissue affinity of high-molecular-weight hyaluronan after oral administration in rats and dogs. J Agric Food Chem. 2008;56(22):10582-93. PubMed PMID: 18959406
17. Laznicek M, Laznickova A, Cozikova D, Velebny V. Preclinical pharmacokinetics of radiolabelled hyaluronan. Pharmacol Rep. 2012;64(2):428-37. PubMed PMID: 22661195
18. Muhammad P, Novianto E, Setyorini M, Legiawati L, Yusharyahya SN, Menaldi SL, Budianti WK. Effectiveness of topical hyaluronic acid of different molecular weights in xerosis cutis treatment in elderly: a double-blind, randomized controlled trial. Arch Dermatol Res. 2024;316(6):329. PubMed PMID: 38829483
19. Zhou R, Yu M. The Effect of Local Hyaluronic Acid Injection on Skin Aging: A Systematic Review and Meta-Analysis. J Cosmet Dermatol. 2025;24(1):e16760. PubMed PMID: 39807700
20. Kyriazidis I, Spyropoulou GA, Zambacos G, Tagka A, Rakhorst HA, Gasteratos K, Berner JE, Mandrekas A. Adverse Events Associated with Hyaluronic Acid Filler Injection for Non-surgical Facial Aesthetics: A Systematic Review of High Level of Evidence Studies. Aesthetic Plast Surg. 2024;48(4):719-741. PubMed PMID: 37563436
21. Baranska-Rybak W, Lajo-Plaza JV, Walker L, Alizadeh N. Late-Onset Reactions after Hyaluronic Acid Dermal Fillers: A Consensus Recommendation on Etiology, Prevention and Management. Dermatol Ther (Heidelb). 2024;14(7):1767-1785. PubMed PMID: 38907876
22. Seki Y, Ohkuma RC, Miyakawa Y, Karakida T, Yamamoto R, Yamakoshi Y. Hyaluronan and chondroitin sulfate in chicken-vegetable bone broth delay osteoporosis progression. J Food Sci. 2024;89(3):1791-1803. PubMed PMID: 38317402

PubMed Topic Searches

1. https://pubmed.ncbi.nlm.nih.gov/?term=oral+hyaluronic+acid+skin+randomized
2. https://pubmed.ncbi.nlm.nih.gov/?term=hyaluronan+skin+aging
3. https://pubmed.ncbi.nlm.nih.gov/?term=topical+hyaluronic+acid+molecular+weight+skin
4. https://pubmed.ncbi.nlm.nih.gov/?term=hyaluronic+acid+filler+adverse+events

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Connections

• Hyaluronic Acid: The Body’s Water-Holding Molecule
• Hyaluronic Acid Benefits: What the Research Shows
• Hyaluronic Acid for Joints
• Hyaluronic Acid for Eyes and Wound Healing
• Hyaluronic Acid as an Antioxidant: Forms and Safety
• Amino Acid Derivatives
• Glucosamine
• Collagen for Skin Elasticity
• Vitamin C for Collagen Synthesis
• Tremella for Skin & Hydration
• Silicon
• UV Radiation