Azelaic Acid Has Real Evidence. Almost None of It Is at 10%

Azelaic acid arrives with a checklist of a reputation. Proper clinical trials. An FDA approval. Gentle on sensitive skin. Fine in pregnancy. Cheap, and on every shelf as a 10% serum.

Every item on that list is true of something. What it is mostly not true of is the bottle most people buy. We read the three United States prescription labels, the largest systematic review, the Cochrane reviews, the acne guideline and the product pages of six non-prescription brands. The evidence is real. Almost all of it was generated at 15 and 20 percent, in prescription formulations, for two specific conditions.

One molecule, two prescription drugs, two different conditions

The usual shorthand is that azelaic acid is FDA-approved for rosacea. True of one brand. Not true of the other brand people name in the same breath.

Product	Approved for
Azelex cream, 20%	Acne (1995)
Finacea gel, 15%	Rosacea (2002)
Finacea foam, 15%	Rosacea (2015)

The Azelex label says the “cream is indicated for the topical treatment of mild-to-moderate inflammatory acne vulgaris”. Nothing else. The Finacea gel label and the foam label both cover the “inflammatory papules and pustules of mild to moderate rosacea”, and the gel label adds a limit that rarely survives into articles: “efficacy for treatment of erythema in rosacea in the absence of papules and pustules has not been evaluated”.

So the approval covers the bumps of rosacea, not redness on its own. No azelaic acid product in the United States is approved for melasma, dark spots or aging. Generic 15% gels exist; they copy Finacea, not a cosmetic serum.

How strong the evidence is, use by use

The claim you will meet most often is that azelaic acid has strong trial evidence for four different uses. As far as we can tell it traces to a 2023 systematic review by King and colleagues, whose title names the four: acne, rosacea, melasma and skin aging. The review itself is open access and we read all of it. Taken one at a time, the four uses look nothing alike.

Use	Evidence, as rated
Rosacea bumps	High quality
Acne	Moderate, three old trials
Melasma	Mostly poor-quality trials
Skin aging	No eligible trial found

Rosacea: the strongest case

This is where the reputation was earned. The two trials behind Finacea gel, published by Thiboutot and colleagues in 2003, randomized 664 people to the gel or to an identical gel with the drug left out, for 12 weeks. Inflammatory lesions fell by 58% against 40% in the first trial, and by 51% against 39% in the second.

The 2015 Cochrane review of rosacea treatments rated the evidence for topical azelaic acid against placebo as high quality and concluded there was “high quality evidence to support the effectiveness of topical azelaic acid”, in the same sentence as ivermectin, brimonidine, doxycycline and isotretinoin. A 2019 update by the same group kept that rating for papules and pustules. King and colleagues, pooling five trials and 2,905 people, found “high quality evidence that AA 15% is more effective than vehicle”.

Against metronidazole, the other standard topical, the picture is less tidy. One 2003 trial of 251 patients found the azelaic acid gel superior. The Cochrane authors, with three head-to-head studies in front of them, wrote that “The results from three studies were contradictory on which of these two treatments was most effective.” King and colleagues read the same comparison more favorably, reporting that “AA was more effective than metronidazole 0.75% for improved erythema severity, overall improvement, and inflammatory lesion counts”.

There is also a cost to being the strong one. A 2025 network meta-analysis of 19 trials and 8,208 people put azelaic acid 20% top for improvement on the investigator’s scale, with 15% comparable to metronidazole and ivermectin. It also found azelaic acid 15% was the only one of those topicals with a statistically significant excess of adverse events. Stinging and burning in the first weeks are on the prescription label too.

Acne: real, but thinner than it sounds

The 2024 American Academy of Dermatology acne guideline lists azelaic acid among its topical treatments and grades it with some care: “For patients with acne, we conditionally recommend azelaic acid.” The certainty of evidence is rated moderate. Benzoyl peroxide and topical retinoids, on the same certainty rating, get a strong recommendation.

The guideline names its evidence: three randomized trials, published in 1989, 1989 and 2007. The headline figure comes from one of them: “In 1 RCT of 92 patients, 28% more patients receiving azelaic acid 20% cream twice daily achieved 50% to 100% reduction in total lesion count compared to vehicle at 3 months.”

A genuine effect, from a drug approved for the purpose. It is also 20% cream, in a trial nearly forty years old, and nowhere near the weight of evidence behind the acne treatments the guideline recommends more firmly.

An independent group reached the same place. A 2020 Cochrane review of six topical acne treatments found that “azelaic acid is probably less effective than benzoyl peroxide” and that there is “probably little or no difference when comparing azelaic acid to tretinoin”, both on moderate-quality evidence.

Melasma: the use it is not approved for

Melasma is where azelaic acid gets sold as a brightener, and where the evidence is oldest and most poorly rated. King and colleagues do report that across their seven melasma trials, “AA 20% was significantly better than vehicle for both severity and global improvement”. Most of those trials, though, set 20% azelaic acid against hydroquinone, the long-standing prescription lightener, and hydroquinone is a high bar rather than a blank cream.

• A 1989 trial of 155 patients found good to excellent results in 73% on azelaic acid against 19% on 2% hydroquinone.
• A 1991 trial of 329 women, against the stronger 4% hydroquinone, found no significant difference between them.
• A 2011 study of 29 women favored azelaic acid over 4% hydroquinone, but its own abstract calls it “an open trial” and asks for larger studies.

Read plainly, parity with the strongest common lightener is a result rather than a shortfall, and the 1991 trial is the largest of the three. The 2010 Cochrane review of melasma treatments put it in one line: azelaic acid did better than 2% hydroquinone “at lightening melasma but not when compared to 4% hydroquinone”. On the field as a whole it was blunter: “The quality of studies evaluating melasma treatments was generally poor and available treatments inadequate.”

Skin aging: no trial at all

The fourth use in the review’s title is the one the review could not support. King and colleagues searched to December 2022 and wrote: “No RCTs were identified in the literature that specifically evaluated hyperpigmentation or anti-aging measures.” Note what else that sentence covers. Melasma has seven trials, but hyperpigmentation in general, which is what most 10% serums are sold for, has none. Their abstract closes by asking for trial evidence. Four uses, then: one well established, one moderate, one shaky, one untested.

Almost every trial behind that reputation used 15 or 20 percent

This is the part the product pages leave out. King and colleagues list the strengths their 43 trials used:

In their words: “Twenty of the trials assessed AA 20% gel or cream, nineteen assessed AA 15% gel or foam, one evaluated AA 5% gel, and two trials did not report the dose of AA.” Two unreported doses leave a small gap, so the honest form of the statement is that none of the 43 is reported as a 10% trial. Two things stop that being the whole story. The 5% trial is a real sub-10% result, an add-on to clindamycin rather than a treatment on its own, and the review rates it high quality. And the 2021 trial below is a 10% trial that is not in the 43 at all, although it was published inside the review’s search window. We could not find it named anywhere in the review.

We then searched Europe PMC ourselves for randomized trials at 10% or below. We found two, and neither tests the kind of product this article is about. The better of the two is a 2021 acne trial from Mostar and Zagreb: double-blind, 68 patients randomized, eight weeks, 10% azelaic acid against the 20% prescription cream, with no blank-cream arm. Both arms improved by similar amounts, and the 10% arm’s figures were if anything slightly better. The catch is what the 10% was: a nanocrystal hydrogel engineered to carry more drug into the skin, which the authors had measured in an earlier penetration study. It was funded by the federal education ministry of Bosnia and Herzegovina and two universities, and also by a research grant from PLIVA Croatia, part of the Teva group, where one of the authors works. The other is from 2026 and put 10% azelaic acid combined with 0.1% retinal against a vehicle, split-face, on 23 people who completed the study, measuring texture, redness and pores by imaging. All four authors list the same company, Skinome Research AB. We read the abstract only, and because two actives went on together it cannot isolate the azelaic acid.

None of this proves that 10% does nothing. In laboratory studies azelaic acid acts on bacteria at concentrations far below 10%, and the molecule is the same at any strength. The 2021 trial makes the point better than we could: 10% matched 20% when the 10% was built to deliver more of the drug. What carries over from a trial is the whole product, not the number on the front. And no trial we found has tested a cosmetic azelaic acid serum on its own. A 10% serum that borrows the reputation is borrowing from a different product, and strength is only one of the things that differ. It is the gap we found with retinol conversion numbers: the direction is well supported, the dose equivalence is not.

What the 10% bottles actually claim

In the United States a product is a drug or a cosmetic according to what it is intended to do, not what is in it. FDA puts it plainly: “Certain claims may cause a product to be considered a drug, even if the product is marketed as if it were a cosmetic.” One of the agency’s own examples is a claim to “increase or decrease the production of melanin (pigment) in the skin”.

Nor is azelaic acid on the list of permitted active ingredients for over-the-counter acne products. That list is benzoyl peroxide, salicylic acid, sulfur, and resorcinol or resorcinol monoacetate combined with sulfur. A non-prescription azelaic acid product that wants to stay a cosmetic therefore has to talk about appearance. Most of the pages we read do. A few do something more interesting.

• The Ordinary Azelaic Acid Suspension 10% stays on the cosmetic side of the line: it “improves the look of uneven skin tone and visibly improves skin texture”. Azelaic acid sits fourth of 17 ingredients, which tells you its rank and nothing about its dose; the dose is on the front of the bottle. Our guide to reading ingredient lists explains why those are two different things.
• Paula’s Choice 10% Azelaic Acid Booster also sticks to appearance, and says “Helps improve the appearance of redness”. It adds that “Azelaic acid’s effectiveness is backed by over 20 years of research”, which is true of azelaic acid. The research was on 15% and 20% prescription formulations.
• Naturium sells what is now called “Azelaic Acid Derivative Complex 10%”. Its ingredient list contains no azelaic acid. Third on that list is potassium azeloyl diglycinate, a different compound made from it, and none of the trials above tested it.
• Geek & Gorgeous aPAD is candid about the same substitution, describing itself as a serum “with a potent Azelaic Acid derivative (Potassium Azeloyl Diglycinate or PAD)”.
• Cos De BAHA Azelaic Acid 10% Facial Serum puts “Fast Rosacea Skin Care Product” in its product name, and on the same page says “our products are not medicines”. Rosacea is a disease, and a disease in a product title is the kind of claim FDA describes. We are not a regulator and we are not calling this unlawful. We are pointing out that the name and the disclaimer pull in opposite directions.
• La Roche-Posay Effaclar A.Z. Gel is sold as an acne treatment, legitimately, because it is an over-the-counter drug. The active ingredient on its label is “Salicylic Acid 1.2%”. Azelaic acid is second on its list of inactive ingredients. The product with azelaic acid in its name is, in regulatory terms, a salicylic acid product.

What the labels say about pregnancy

Azelaic acid is often described as pregnancy-safe, and at least one brand we read, Geek & Gorgeous, prints “Pregnancy-safe” on its page. The prescription labels are more careful than that, and they do not even agree with each other in form.

The current Finacea labels, gel and foam, say azelaic acid is minimally absorbed and that “maternal use is not expected to result in fetal exposure to the drug”. They also report that in animal studies with oral dosing, toxicity to the developing fetus appeared at “162, 19, and 65 times the maximum recommended human dose” in rats, rabbits and monkeys, with no malformations. The older-format Azelex label says “There are, however, no adequate and well-controlled studies in pregnant women.” and that “this drug should be used during pregnancy only if clearly needed”.

The acne guideline lands in much the same place: fetal harm from topical azelaic acid is “not expected based on limited expected systemic absorption”. That is an expectation reasoned from low absorption, not a trial in pregnant women, because none has been done. It is a question for whoever looks after the pregnancy, not for a product page and not for us.

Two more label warnings rarely get repeated. The Finacea gel label notes that hypopigmentation has been reported and that “Since azelaic acid has not been well studied in patients with dark complexion, monitor these patients for early signs of hypopigmentation”. It also records that “Worsening of asthma has been reported” in people using azelaic acid formulations.

How it is thought to work

Three mechanisms are usually listed. Each has a primary source, and all three are laboratory findings rather than measurements in human skin.

• Pigment. The story starts with a yeast. In 1978 Nazzaro-Porro and Passi isolated compounds from cultures of Pityrosporum, a yeast that lives on skin, which blocked tyrosinase, the enzyme that starts melanin production. The abstract names them as the nine-carbon and eleven-carbon dicarboxylic acids, and azelaic acid is the nine-carbon one. Of those compounds, “Enzymatic kinetic studies showed that they act as competitive inhibitors of tyrosinase.”
• Bacteria. A 1994 laboratory study found that azelaic acid disrupts the internal pH of the acne bacterium and killed it quickly at pH 4.0. At pH 6.0 the picture changed: “At pH 6.0 little change in viable numbers of P. acnes and S. epidermidis were observed over a 2 h incubation period.” The antibacterial effect leans heavily on acidity.
• Inflammation. A 1991 study found that azelaic acid cut the reactive oxygen species released by human white blood cells in the lab, which the authors proposed as part of its effect on inflamed skin.

Who paid for the evidence

The planning note we started from called azelaic acid the active nobody is selling you. We could not measure that, and in one respect it is the wrong way round. The review behind the four-uses claim was paid for by a company. Its acknowledgments say: “The authors were funded by Dermatica Pharma Ltd. to conduct and/or provide expert consultation on this systematic review.” All six authors give the Dermatica Institute of Clinical Excellence as their affiliation. Dermatica is a UK online service whose clinicians prescribe personalized skin formulas.

That does not make the review wrong. It is registered, it follows the Cochrane method, and its rosacea findings agree with the independent Cochrane review. It does mean that the largest recent review of azelaic acid was paid for by a company in the business of prescribing skin treatments, and that of the two 10% trials we found, one was part-funded by a generics manufacturer and the other was run by a skincare company’s own research arm. Most evidence in this field has someone behind it. The useful question is whether a finding survives when someone else looks, and for rosacea it does.

So is azelaic acid worth using

• Rosacea bumps: the strongest case, at 15%, on prescription.
• Acne: approved at 20%, conditionally recommended, moderate evidence.
• Melasma: not approved, and the trials are mostly poor.
• Skin aging: no trial found.
• At 10%: not one of the 43 trials in the largest review.

Where to find these

The two links below are affiliate links, and the disclosure above the article applies to both. Prescription azelaic acid cannot be bought through a link and we have not tried. These two are cosmetics that contain azelaic acid itself rather than a derivative. Neither has been tested in a trial on its own.

• The Ordinary Azelaic Acid Suspension 10% (paid link)
• Paula’s Choice 10% Azelaic Acid Booster (paid link)

References

• Almirall. Azelex (azelaic acid cream) 20%, prescribing information, revised February 2024. accessdata.fda.gov. Read in full.
• LEO Pharma. Finacea (azelaic acid) Gel, 15%, prescribing information, revised November 2021. accessdata.fda.gov. Read in full.
• LEO Pharma. Finacea (azelaic acid) Foam, 15%, prescribing information, revised December 2020. accessdata.fda.gov. Read in full.
• United States Food and Drug Administration. Drugs@FDA records for NDA 020428, NDA 021470 and NDA 207071.
• United States Food and Drug Administration. Is It a Cosmetic, a Drug, or Both? (Or Is It Soap?). fda.gov.
• 21 CFR 333.310, Acne active ingredients, revised as of 1 April 2024. govinfo.gov.
• King S, Campbell J, Rowe R, Daly ML, Moncrieff G, Maybury C. A systematic review to evaluate the efficacy of azelaic acid in the management of acne, rosacea, melasma and skin aging. Journal of Cosmetic Dermatology 2023;22(10):2650-2662. Open access. Read in full. Funded by Dermatica Pharma Ltd.
• van Zuuren EJ, Fedorowicz Z, Carter B, van der Linden MM, Charland L. Interventions for rosacea. Cochrane Database of Systematic Reviews 2015, CD003262.pub5. Europe PMC. Abstract read.
• van Zuuren EJ, Fedorowicz Z, Tan J, et al. Interventions for rosacea based on the phenotype approach: an updated systematic review including GRADE assessments. British Journal of Dermatology 2019. Europe PMC. Abstract read.
• Thiboutot D, Thieroff-Ekerdt R, Graupe K. Efficacy and safety of azelaic acid (15%) gel as a new treatment for papulopustular rosacea: results from two vehicle-controlled, randomized phase III studies. Journal of the American Academy of Dermatology 2003. Europe PMC. Abstract read.
• Elewski BE, Fleischer AB, Pariser DM. A comparison of 15% azelaic acid gel and 0.75% metronidazole gel in the topical treatment of papulopustular rosacea: results of a randomized trial. Archives of Dermatology 2003. Europe PMC. Abstract read.
• Reynolds RV, Yeung H, Cheng CE, et al. Guidelines of care for the management of acne vulgaris. Journal of the American Academy of Dermatology 2024. jaad.org. Read in full.
• Rajaratnam R, Halpern J, Salim A, Emmett C. Interventions for melasma. Cochrane Database of Systematic Reviews 2010, CD003583.pub2. Europe PMC. Abstract read.
• Verallo-Rowell VM, Verallo V, Graupe K, et al. Double-blind comparison of azelaic acid and hydroquinone in the treatment of melasma. Acta Dermato-Venereologica Supplementum 1989. Europe PMC. Abstract read.
• Baliña LM, Graupe K. The treatment of melasma. 20% azelaic acid versus 4% hydroquinone cream. International Journal of Dermatology 1991. Europe PMC. Abstract read.
• Farshi S. Comparative study of therapeutic effects of 20% azelaic acid and hydroquinone 4% cream in the treatment of melasma. Journal of Cosmetic Dermatology 2011. Europe PMC. Abstract read.
• Gaudicheau C, Ahlström M, Gillbro JM, Åkerström U. Efficacy and safety of a novel anhydrous 0.1% retinal and 10% azelaic acid concentrate for blemish-prone skin. International Journal of Cosmetic Science 2026. Europe PMC. Abstract read; full text not read.
• Nazzaro-Porro M, Passi S. Identification of tyrosinase inhibitors in cultures of Pityrosporum. Journal of Investigative Dermatology 1978. Europe PMC. Abstract read.
• Bojar RA, Cunliffe WJ, Holland KT. Disruption of the transmembrane pH gradient, a possible mechanism for the antibacterial action of azelaic acid in Propionibacterium acnes and Staphylococcus epidermidis. Journal of Antimicrobial Chemotherapy 1994. Europe PMC. Abstract read.
• Akamatsu H, Komura J, Asada Y, Miyachi Y, Niwa Y. Inhibitory effect of azelaic acid on neutrophil functions: a possible cause for its efficacy in treating pathogenetically unrelated diseases. Archives of Dermatological Research 1991. Europe PMC. Abstract read.
• Tomić I, Miočić S, Pepić I, Šimić D, Filipović-Grčić J. Efficacy and Safety of Azelaic Acid Nanocrystal-Loaded In Situ Hydrogel in the Treatment of Acne Vulgaris. Pharmaceutics 2021;13(4):567. Europe PMC. Open access, read in full.
• Liu H, Yu H, Xia J, et al. Topical azelaic acid, salicylic acid, nicotinamide, sulphur, zinc and fruit acid (alpha-hydroxy acid) for acne. Cochrane Database of Systematic Reviews 2020, CD011368.pub2. Europe PMC. Abstract read.
• Shaheen EA, Aljefri YE, Ghaddaf AA, et al. The efficacy and safety of minocycline, metronidazole, ivermectin, and azelaic acid in moderate-to-severe papulopustular rosacea: a systematic review and network meta-analysis. JAAD International 2025. Europe PMC. Abstract read.
• Product pages as published by the manufacturers and read 16 September 2026: The Ordinary, Paula’s Choice, Naturium, Geek & Gorgeous, Cos De BAHA and La Roche-Posay.