New?New to peptides?Start here →

Decoding

Carnosine_Dosage, benefits & legal status

Also known as L-carnosine, beta-alanyl-L-histidine, beta-alanyl-histidine, karnosine

By the Peptide Decoding Editorial Team

Published November 5, 2026

Destroyed in human blood in about a minute.

LongevityDipeptide (beta-alanyl-L-histidine)Supplement

InLongevity and energyTaken without a needle

Dose500 mg to 2 g per day in supplements and trials

FrequencyDaily

RouteBy mouth (capsule or powder), and on the skin in cosmetics

StatusSupplement

CycledNot cycled

Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.

See how this dose compares across the library →

What is Carnosine?

Plain language first. The technical label stays, but it never stands alone.

Overview

Carnosine is a two-part molecule your own muscles are full of, sold as an anti-aging supplement, put into skin creams, and dripped into eyes as a cataract remedy. One measurement reorganizes all of it: in human blood, carnosine lasts about a minute. Humans carry an enzyme in plasma that chops it in half, and mice and rats do not, so most of the encouraging animal research was done in a species where the molecule survives. In people, a controlled study found you need 6 to 15 grams to reliably raise blood levels, and 15 grams caused dose-limiting problems. A typical supplement capsule is 500 milligrams. None of that makes carnosine uninteresting, and it does mean the gap between what is sold and what has been shown is unusually wide, in a way that is measurable rather than a matter of opinion.

The technical version

Carnosine is a naturally occurring dipeptide, beta-alanyl-L-histidine, CAS 305-84-0, formula C9H14N4O3, molecular weight 226.2328, concentrated in skeletal muscle and brain. Its first residue is a beta-amino acid, so the peptide bond is not a standard peptidase target, but human plasma carries serum carnosinase, giving a measured plasma half-life of 1.20 plus or minus 0.36 minutes. That enzyme is present in primate blood and absent from the blood of mice and rats, both of which carry only the tissue form. It is sold as an oral supplement, used as a cosmetic ingredient, and marketed in derivative form as eye drops. No FDA-approved drug use exists. The zinc complex polaprezinc is approved in Japan for gastric indications.

What it's used for

Sold as an oral supplement for aging, glycation and cognition, used as a cosmetic ingredient in skin products, and sold in derivative form as eye drops. No approved medical use, and the oral evidence for cognition is rated low quality.

How does Carnosine work?

What it does in the body, and where.

One enzyme governs almost everything about this molecule in people, and understanding it in order makes the rest of the page predictable rather than surprising.

01
What carnosine is, and the unusual bond
Two residues: beta-alanine joined to histidine. The first is a beta-amino acid, meaning its amino group sits one carbon further along than in a normal amino acid, so the resulting bond is not a standard target for the peptidases that break down ordinary dietary peptides. That is why carnosine accumulates in muscle and brain in the first place, at concentrations high enough to act as a buffer and a scavenger of reactive carbonyls.
02
The enzyme that exists anyway
Humans have a dedicated enzyme for it, serum carnosinase, circulating in plasma. Measured directly, carnosine's half-life in human plasma is 1.20 plus or minus 0.36 minutes. For comparison in the same study, balenine lasted 34.9 minutes and anserine 2.14 minutes, and that paper's own title describes balenine as a carnosinase-resistant alternative to carnosine. Resistance is the selling point because carnosine does not have it.
03
Why the animal literature does not transfer
The species difference is not subtle. Human plasma activity is 2.73 plus or minus 0.54 micromol per mL per hour against 53.1 in hamster, and the circulating enzyme is present in primate blood and absent from the blood of other mammals, with mice and rats carrying only the tissue form. So oral carnosine work in rodents studies a species where the molecule is not destroyed on the way in. Encouraging rodent results are not evidence of a human effect, and this is the clearest mechanistic reason on this site for that kind of gap.
04
Genotype decides whether a dose does anything
In a challenge study at 60 mg per kg, only 8 of 25 healthy adults showed any measurable rise in plasma carnosine, and the non-responders carried roughly twice the carnosinase protein. Whether an oral dose reaches the bloodstream is partly determined by which version of the enzyme gene a person has. One caveat on the dose-finding work: the 16-person study used a carnosinase inhibitor in its collection tubes and never measured endogenous carnosinase activity, so it characterizes dosing rather than settling the enzymology.
05
Beta-alanine is the opposite strategy, not the same one
Beta-alanine has a large sports-nutrition evidence base, and it is routinely offered as support for oral carnosine. It is the reverse. Beta-alanine works because it bypasses the enzyme entirely: it is absorbed as a free amino acid, reaches muscle, and is assembled into carnosine inside the cell where plasma carnosinase cannot reach. Its evidence supports raising muscle carnosine by supplying the precursor, and says nothing about swallowing the finished dipeptide. Worth knowing that the 2026 meta-analysis on cognition included no beta-alanine trials at all, and its funder markets a beta-alanine brand.

Pathway

THE PEPTIDE

Carnosine

ACTS ON

Serum carnosinase, the enzyme that meets it first

RESULT

Cut apart in about 1.2 minutes in human plasma

RESULT

Not cut apart in mouse or rat blood, where most research was done

A schematic of the compound's mechanism, not a diagnostic image.

What else is it used for?

Each group carries its own evidence level.

Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.

The enzyme that governs everything else

peer-reviewed-human

Human trialHalf-life in human plasma is 1.20 plus or minus 0.36 minutes, measured directly. Balenine lasts 34.9 minutes and anserine 2.14 in the same study.
Lab studyHuman plasma carnosinase activity is 2.73 plus or minus 0.54 micromol per mL per hour against 53.1 in hamster. The circulating form is present in primate blood, while mice and rats carry only the tissue form.
Human trialIn a 25-person oral challenge at 60 mg per kg, only 8 participants showed any measurable plasma rise, and non-responders carried roughly twice the carnosinase protein.
Lab studyBeta-alanine works by bypassing this enzyme, being absorbed as a free amino acid and assembled into carnosine inside muscle. Its evidence base therefore gives no support to swallowing the finished dipeptide.

Dose, and the size of the gap

peer-reviewed-human

Human trialA 16-person study found 6 to 15 g needed for reliable plasma elevation, 10 g for brain detection, little detectable beyond 4 hours, and dose-limiting toxicity at 15 g.
No dataSupplements cluster at 500 mg and cognition trials used 100 to 2,000 mg daily, so the shown-to-be-absorbed doses are roughly 12 to 30 times a typical capsule.
No dataThat study used a carnosinase inhibitor in its collection tubes and never measured endogenous carnosinase, and its brain arm had 5 participants, too few for statistical inference.

Cognition, where the answer is no

tested-and-failed

ReviewA 2026 meta-analysis of 13 studies rates cognition evidence low and notes most individual trials found no significant difference for L-carnosine alone.
ReviewThe two significant pooled results come from anserine and carnosine 3 to 1 combinations, majority anserine.
Human trialThe cleanest dedicated trial, 2 g daily for 14 weeks, was null on every cognitive measure, all p at or above 0.18.
No dataThe one positive signal is an explicitly post-hoc age-stratified subgroup of a secondary outcome, benefiting only healthy 23 to 35 year olds across three strata and ten tests.
No dataZero beta-alanine trials were included in that review, and its funder markets a beta-alanine brand.

Skin, where the main study contradicts itself

Early research

No dataNo controlled human trial of topical carnosine could be found, against searches that did retrieve other topical-peptide primary literature, so the absence is controlled rather than a search artifact.
Lab studyThe main source is ex vivo explants from one 41-year-old donor in triplicate at 0.2%, with no living person treated and no cream-without-carnosine arm, and its own authors acknowledge one is needed.
No dataSeveral of its reported reductions exceed 100%, at minus 150%, minus 136%, minus 122% and minus 108%, with no explanation of the metric.
No dataIts text and its Table 4 invert which arm worked: minus 49% at p below 0.01 and minus 2% not significant in the text, against 42% not significant and minus 136% at p=0.03 in the table.
No dataThe alternative human dataset is a 466-person injected trial whose control arm received no intervention at all, testing a product containing carnosine plus hyaluronate plus three amino acids plus a vitamin.

The eye drops, and what they are legally

none

ReviewThe Cochrane review of N-acetylcarnosine drops for age-related cataract included zero studies and found no convincing evidence of reversal or slowed progression.
No dataThe only two human trials, covering 114 people, are awaiting classification, are unregistered, and were funded and organized by the company that markets the product and holds the worldwide patent.
RegulatoryOn the FDA ingredient record, N-acetylcarnosine appears in 9 products and is an inactive ingredient in every one, with the declared actives being glycerin, carboxymethylcellulose or hypromellose. The products are legally marketed as lubricant eye drops.
RegulatoryCarnosine itself appears in 370 records, all cosmetic use in sunscreens and skin protectants, never as an active ingredient. A control query on ibuprofen returned 1,173 records, so the pattern is real rather than a query artifact.

The cosmetic market, and what the sources actually say

none

lab-analysisA major brand's reformulated serum does contain carnosine at 0.3%, where it sits eleventh of eighteen ingredients.
No dataThat brand's own product page never mentions carnosine at all, and every clinical figure in circulation is for the whole formula, with nothing attributing anything to the carnosine in it.
No dataA new plant-derived carnosine ingredient was announced in August 2026 with a use level as low as 0.2%, no data disclosed, no INCI name given, and a release that contradicts itself between fully plant-derived and biofermentation.
No dataA reformulation date in circulation for that serum does not check out: two independent outlets published coverage six days before it, and neither gives a launch date.

Often left out

Four things get repeated about carnosine, and the first one explains the other three. Its half-life in human plasma is 1.20 minutes, because humans carry a dedicated enzyme in blood that mice and rats lack in blood entirely. So rodent oral-carnosine research, most of the encouraging literature, was done in a species where the molecule is not destroyed on the way in. Second, the beta-alanine evidence base is offered as support, when beta-alanine works by the opposite route: it bypasses that enzyme, supplying a precursor that muscle assembles into carnosine internally. Third, the dose. Supplements sell 500 mg capsules and the trials used up to 2 g, while the one controlled dose-finding study needed 6 to 15 g for a reliable blood rise and hit dose-limiting toxicity at 15 g. Fourth, the eye drops. The Cochrane review on cataract included zero studies, the only two human trials are unregistered and were run by the patent holder, and on the FDA's own ingredient record the derivative is an inactive ingredient in all nine products, sold as artificial tears. Two smaller corrections: the topical claim rests on a single-donor ex vivo study whose text and tables disagree about which arm worked, and a widely repeated reformulation date for one branded serum does not check out, since coverage appeared six days earlier.

The published record

Research index

486

Papers about Carnosine

Searched: carnosine, L-carnosine, beta-alanyl-L-histidine.

Left out: beta-alanine (THE most important rejection, and the reason is mechanistic rather than nominal. Beta-alanine works precisely BECAUSE it bypasses serum carnosinase: absorbed as a free amino acid and assembled into carnosine INSIDE muscle where plasma CN1 cannot reach. Its large sports-nutrition evidence base therefore gives NO support to oral carnosine, and it must not be merged in); N-acetylcarnosine (a separate registered substance, UNII 0TPN86OQIF, sold as cataract eye drops. The Cochrane review on that use included ZERO studies, and on the FDA ingredient record it is an INACTIVE ingredient in all nine products, which are legally lubricant eye drops); carcinine (a separate registered substance, UNII WIV0W167TC, C8H14N4O, MW 182.22, which is carnosine minus a carbon dioxide. Consumers meet it as a cosmetic ingredient); D-carnosine (a separate registered substance, UNII LE2264A962, the mirror-image form used in carnosinase-resistance research); anserine (a methylated relative with a 2.14-minute plasma half-life. The only two significant pooled cognition results come from anserine/carnosine 3:1 combinations, which are MAJORITY ANSERINE and are routinely reported as carnosine findings); balenine (another relative, at 34.9 minutes, whose key paper's own title describes it as a CARNOSINASE-RESISTANT ALTERNATIVE to carnosine); polaprezinc (zinc L-carnosine, approved in JAPAN ONLY for peptic ulcer and dyspepsia. A different substance including zinc, and a gastric indication that is not evidence for skin, eye or cognitive claims); carnosic acid (an unrelated rosemary diterpene whose name collides in keyword search).

248 papers tagged human · 125 not reviews or lab · 22 clinical trial publications

How the compound was given: 70 applied to skin · 35 injected · 63 by mouth or rectal · 3 intranasal · 342 route not stated in the abstract

Read from each paper's indexing terms and abstract, by rule. A paper that mentions a cream studied a cream, not necessarily the product being sold.

53 registered trials · 5 with posted results

Furthest stage reached: Phase 4 as registered, status not updated

Compare this against the whole library →

Browse the records

In animals192

In the lab21

Reviews78

Senior author shareSpread across many groups

Evidence summary

Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count. A preprint and its journal version count once. 486 papers and 53 trials indexed in detail.

Compound field notes

At a glance

Four things to know about Carnosine

Evidence

Supplement

How much, and do you cycle it?

The range, and whether you take breaks.

500 mg to 2 g per day in supplements and trials, daily. Not cycled Community practice

Taken daily as a supplement rather than in blocks. The open question is whether an oral dose reaches the bloodstream at all, not tolerance.

Compare this against the whole library →

How long does it stay in the body?

The half-life, and where the figure comes from.

1.2 minutes in human plasmaHuman study

Measured directly as 1.20 plus or minus 0.36 minutes, one of the shortest figures on this site. The cause is serum carnosinase, an enzyme in human plasma, and the comparison in the same study makes the point: balenine lasted 34.9 minutes and anserine 2.14. Two consequences follow. One: mice and rats lack the circulating form of this enzyme, carrying only the tissue version, so rodent oral work does not transfer. Two: in a 25-person challenge, only 8 people showed any measurable plasma rise, with non-responders carrying about twice the enzyme protein, so whether a dose survives is partly genetic.

Source: Scientific Reports 2023, volume 13, DOI 10.1038/s41598-023-33300-1

You can compare this against the whole library to see where it sits.

How is it given?

Dosing context and source notes.

No draw available

Nutrients 2025, volume 17, article 2130, 16 participants

Sold as capsules and powder, so no vial draw can be shown and the calculator does not apply. Supplements cluster at 500 mg and the cognition trials used 100 to 2,000 mg per day. The figure worth holding beside those: a 16-person controlled study found 6 to 15 g was needed for reliable plasma elevation and 10 g for brain detection, with 15 g reaching dose-limiting toxicity. So the doses that have been shown to raise blood levels are roughly 12 to 30 times a typical capsule.

How do you store it?

Before mixing, and after.

Room temperature. Cool, dry, out of light.

Carnosine is taken as a pill or capsule. Keep it in its original container at room temperature, away from heat, humidity, and direct sun. No fridge or mixing needed. Check the expiration date on the bottle.

What are the side effects and cautions?

Known cautions and warnings for this compound.

Who should avoid it

Check these before anything else.

Carrying over rodent findings, since mice and rats lack the blood enzyme that destroys carnosine in humans within about a minute
Treating the beta-alanine sports-nutrition evidence as support for oral carnosine, because beta-alanine works precisely by bypassing that enzyme
Using N-acetylcarnosine eye drops as a cataract treatment, since the Cochrane review on that question included zero studies and the products are legally marketed in the US as lubricant eye drops

Stop and get help

These are emergencies. Seek care.

Nausea, cramping or diarrhea at gram-scale doses, the point at which tolerability problems have been reported
Any eye pain, discharge or vision change while using eye drops, all of it needing an eye examination rather than more drops

Common effects

Expected, and usually mild.

Little at supplement doses. Gastrointestinal effects appear at the gram-scale doses that actually raise blood levels.

Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.

Is Carnosine approved?

And where the numbers on this page come from.

Not as a medicine. Carnosine is sold without a prescription as a supplement, which is a different thing from being approved as a drug.

Approval status
SupplementSold without a prescription as a dietary supplement. The FDA does not approve supplements before they are sold, and being easy to buy says nothing about whether it works.
Route
By mouth (capsule or powder), and on the skin in cosmetics
Checked
5 November 2026
Dose
From community reports. No regulator or trial established this dose.
Vial size
From what vendors typically list; not a recommendation.
Sources
Scientific Reports, plasma stability of carnosine and its analogs Nutrients, oral dose-finding and brain detection in 16 participants Nutrients, systematic review and meta-analysis of carnosine and cognition Skin Pharmacology and Physiology, a carnosine facial cream against glycation in skin explants Cochrane Database of Systematic Reviews, N-acetylcarnosine drops for age-related cataract FDA substance registration record for carnosine

What has happened recently

A supplement and a cosmetic ingredient in the US, with no approved drug use. The openFDA record is unusually clear on this, and worth reading because it reframes a whole product category. Against a control query returning 1,173 records for ibuprofen, carnosine returns 370 records, every one of them cosmetic use in sunscreens and skin protectants and never as an active ingredient. N-acetylcarnosine returns 9 records, and in every case it is listed as an inactive ingredient, with the declared actives being glycerin, carboxymethylcellulose or hypromellose. So the products sold as cataract drops are legally marketed in the US as over-the-counter lubricant eye drops, artificial tears, with the carnosine derivative as an inactive ingredient. Separately, the zinc complex polaprezinc is approved in Japan only, for peptic ulcer and dyspepsia: a gastric indication involving zinc, and not evidence for skin or cognitive claims. Identity is fully documented: UNII 8HO6PVN24W, CAS 305-84-0, C9H14N4O3, 226.2328, INCI name CARNOSINE. Four look-alikes have their own registry records and consumers meet all of them: D-carnosine, N-acetylcarnosine, carcinine at 182.22, equal to carnosine minus a carbon dioxide, and a decarboxylated cosmetic form.

You can compare this against the whole library, or read how to check a seller.

What else is like Carnosine?

Others in Longevity and energy, side by side.

If you're weighing Carnosine, it's worth reading CB4211, GDF-11, and Nicotinamide Riboside (NR) in the same class.

YOU ARE HERE

CARNO2 residues

Carnosine

Destroyed in human blood in about a minute.

Supplement or cosmetic

Dose: 500 mg to 2 g per day in supplements and trials
How often: Daily

CB4211

A modified MOTS-c analog that completed human safety trials and was abandoned over its formulation.

Investigational

Dose: 25 mg per day in the phase 1b stage
How often: Once daily

GDF-11

The young blood rejuvenation protein, and the field that spent a decade arguing about it.

Research only

Dose: Research only
How often: Not established

Nicotinamide Riboside (NR)

The NAD+ precursor that kept its paperwork in order.

Supplement or cosmetic

Dose: 300 up to 1,000 mg per day
How often: Daily

Compare peptides used for aging and mitochondria Compare oral, nasal, and topical peptides

Guides for this compound

mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
How to Read a Peptide COA
What the purity number does and does not tell you, and how to spot an edited report.
How to Vet a Peptide Vendor
Independent COAs, HPLC purity, and the red flags that mean walk away.

Sources

Scientific Reports, plasma stability of carnosine and its analogs(2023)
Volume 13. The single most important number on this page: carnosine's half-life in human plasma is 1.20 plus or minus 0.36 minutes, against 34.9 minutes for balenine and 2.14 for anserine. The paper's own title describes balenine as a carnosinase-resistant alternative to carnosine, stating the problem from the other direction. It also reports the species gap in numbers: human plasma activity 2.73 plus or minus 0.54 micromol per mL per hour against 53.1 in hamster, with the circulating enzyme present in primate blood and mice and rats carrying only the tissue form.
Nutrients, oral dose-finding and brain detection in 16 participants(2025)
Volume 17, article 2130. The dose study nobody quotes. Reliable plasma elevation required 6 to 15 g, brain detection by spectroscopy required 10 g in 5 participants, little was detectable beyond 4 hours, and 15 g reached dose-limiting toxicity. Set against supplement capsules of 500 mg and cognition trials using 100 to 2,000 mg per day, this is the clearest statement of the gap between what is sold and what has been shown to get in. One limitation: the study used a carnosinase inhibitor in its collection tubes and never measured endogenous carnosinase activity, and the brain arm had 5 participants, too few for statistical inference.
Nutrients, systematic review and meta-analysis of carnosine and cognition(2026)
Volume 18, article 1385. Thirteen studies, with cognition rated low on the GRADE framework and the authors noting that individual trials mostly found no significant cognitive differences for L-carnosine alone. The two significant pooled results come from anserine and carnosine 3 to 1 combinations, majority anserine rather than carnosine. Two disclosures worth carrying: zero beta-alanine trials were included, and the review's funder is a company marketing a beta-alanine brand. The cleanest dedicated trial, 2 g daily for 14 weeks, was null on every cognitive measure with all p values at or above 0.18, and the one positive signal in that literature is an explicitly post-hoc age-stratified subgroup of a secondary outcome, benefiting only healthy 23 to 35 year olds across three strata and ten tests.
Skin Pharmacology and Physiology, a carnosine facial cream against glycation in skin explants(2018)
Volume 31, pages 324 to 331. The main source behind topical carnosine claims, and it has three problems that are visible in the paper itself. It used ex vivo explants from one donor, a 41-year-old woman, in triplicate at 0.2% carnosine with glycation induced chemically, so no living person was treated. Several reported reductions exceed 100%, at minus 150%, minus 136%, minus 122% and minus 108%, with no explanation of the metric. Worse, the paper contradicts itself on its primary numbers: the running text gives one arm as minus 49% at p below 0.01 and the other as minus 2% and not significant, while Table 4 gives 42% not significant and minus 136% at p=0.03, inverting which arm worked. There is no cream-without-carnosine arm, and the authors acknowledge one is needed, and three authors are employees of the company that manufactures the tested cream.
Cochrane Database of Systematic Reviews, N-acetylcarnosine drops for age-related cataract(2017)
The strongest statement of absence available on this page. The review included zero studies and concluded there is no convincing evidence that these drops reverse cataract or prevent its progression. The only two human trials in existence, covering 114 people, are awaiting classification, are unregistered, and were funded and organized by the company that markets the product and holds the worldwide patent.
FDA substance registration record for carnosine(2026)
UNII 8HO6PVN24W, CAS 305-84-0, formula C9H14N4O3, molecular weight 226.2328, systematic name beta-alanyl-L-histidine, INCI name CARNOSINE. One stereocenter only, because beta-alanine is achiral. The registry also holds separate records for the four look-alikes a consumer will meet: D-carnosine, N-acetylcarnosine, carcinine at C8H14N4O and 182.22, equal to carnosine minus a carbon dioxide, and a decarboxylated cosmetic form.

Beyond these, 539 records are indexed. Browse the records