SkincareIngredient GuideAug 2026

Azelaic Acid 20 Percent: What It Treats and How It Compares

Azelaic acid is one of the few skincare actives with an approved drug label, a Cochrane review on three separate conditions, and a mechanism its own label admits is not fully known. This page stays with the ingredient: what regulators approved it for, what the trials found, and where it sits next to the retinoid, the niacinamide and the hydroquinone people already own.

20%

Approved cream strength, for acne

15%

Approved gel and foam strength, for rosacea

8 of 20

US listings under an approved application

What Azelaic Acid Is

Azelaic acid is a saturated dicarboxylic acid, chemically 1,7-heptanedicarboxylic acid, molecular weight 188.22. The US prescribing information for the 20 percent cream describes it as a dietary constituent found in whole grain cereals and animal products, one the body also forms from longer chain dicarboxylic acids and from the metabolism of oleic acid. Endogenous plasma concentrations of 20 to 80 nanograms per millilitre and daily urinary excretion of 4 to 28 milligrams are listed on that label, both of which the label says depend heavily on what a person eats.

That matters for a practical reason. The same label reports that roughly 4 percent of a topically applied dose is absorbed systemically, and that after topical treatment plasma concentration and urinary excretion were not significantly different from baseline levels. In other words the amount reaching the bloodstream from a face application sits inside the noise of a normal diet.

The mechanism is not settled, and the label says so. The 20 percent cream label states plainly that the exact mechanism of action is not known, then lists in vitro findings while noting that their clinical significance is unknown. The 15 percent foam label goes further for its own indication: the mechanisms by which azelaic acid interferes with the pathogenic events in rosacea are unknown. Anyone describing a confident mechanism for this ingredient is going past what the regulator accepted.

The in vitro findings themselves are old and reasonably consistent. A 1987 review reported that azelaic acid is a reversible inhibitor of tyrosinase and other oxidoreductases in vitro, inhibits mitochondrial respiration, and has antimicrobial effects on aerobic and anaerobic organisms. The same review noted a dose and time dependent cytotoxic effect on malignant melanocytes in tissue culture, while also reporting that tumour cell lines containing no tyrosinase were equally affected, which is a result that complicates the neat tyrosinase story rather than confirming it (Nazzaro-Porro, J Am Acad Dermatol 1987, PMID 2963038). Cell culture is not skin, and none of this is a human outcome.

One human observation does sit on the label. Electron microscopic and immunohistochemical evaluation of skin biopsies from people treated with the 20 percent cream showed a thinner stratum corneum, fewer and smaller keratohyalin granules, and less filaggrin in the epidermal layers, which the label reads as evidence of reduced microcomedo formation.

What It Is Approved To Treat

Two indications, and neither of them is melasma. These are United States approvals; every other country runs its own register, and a product legally sold in Vietnam has a Vietnamese registration that these records say nothing about.

Product	Approved indication	Application
AZELEX cream, 20 percent	Mild to moderate inflammatory acne vulgaris	NDA 020428
Azelaic acid gel, 15 percent	Inflammatory papules and pustules of mild to moderate rosacea	NDA 021470
FINACEA foam, 15 percent	Inflammatory papules and pustules of mild to moderate rosacea	NDA 207071

The 15 percent gel label carries a limitation of use that is routinely dropped when the ingredient is written up. In substance: some reduction of erythema did occur in the trials, in patients who also had papules and pustules, but efficacy for treating erythema in rosacea in the absence of papules and pustules has not been evaluated. Both halves of that sentence are load bearing. Redness improved in people who had bumps, and redness alone was never tested.

Nothing above licenses azelaic acid for pigment. Melasma use in the United States is off label, which does not mean unsupported, it means the trial package was never filed for that indication.

The Acne Evidence

The best single appraisal is a 2020 Cochrane review of topical azelaic acid, salicylic acid, nicotinamide, sulphur, zinc and alpha hydroxy acid for acne. It included 49 trials with 3,880 reported participants in total, run in clinics, hospitals, research centres and universities across Europe, Asia and the USA. The vast majority of participants had mild to moderate acne, were aged 12 to 30 with a range of 10 to 45, and were female. Twenty six of the studies were judged at high risk of bias in at least one domain (Liu et al., Cochrane Database Syst Rev 2020, PMID 32356369).

On the participant assessed global improvement outcome, the review reported that azelaic acid is probably less effective than benzoyl peroxide, risk ratio 0.82, 95 percent confidence interval 0.72 to 0.95, from one study of 351 participants, moderate certainty. It also reported probably little or no difference against tretinoin, risk ratio 0.94, 95 percent confidence interval 0.78 to 1.14, from one study of 289 participants, moderate certainty. Both of those are single studies, not pooled bodies of work, and the review authors closed by asking for better designed head to head trials against commonly used active drugs.

That result is worth holding next to the older literature, because it does not match it. A 1996 overview of European trials described 20 percent azelaic acid cream as having overall efficacy comparable to tretinoin 0.05 percent, benzoyl peroxide 5 percent and topical erythromycin 2 percent, and reported that it does not induce resistance in Propionibacterium acnes. That overview was authored from the clinical development department of the company developing the product (Graupe et al., Cutis 1996, PMID 8654128). Twenty four years later, with the evidence graded by an independent group, benzoyl peroxide came out ahead in the single 351 participant trial that compared the two.

Where the guideline puts it. The 2024 American Academy of Dermatology acne guideline issued 18 evidence based recommendations. Strong recommendations went to benzoyl peroxide, topical retinoids, topical antibiotics and oral doxycycline. Azelaic acid received a conditional recommendation, alongside topical clascoterone and salicylic acid (Reynolds et al., J Am Acad Dermatol 2024, PMID 38300170). Conditional is not a dismissal. It means the panel judged the balance of benefits, harms and certainty to be closer, so the choice depends more on the individual.

The Rosacea Evidence

This is where azelaic acid has its strongest grade. A 2015 Cochrane review of rosacea interventions included 106 studies comprising 13,631 participants in total, restricted at selection to randomised trials in people with moderate to severe rosacea, mean age 48.6, mostly papulopustular. Pooling participants own assessments from four trials, it found azelaic acid more effective than placebo, risk ratio 1.46, 95 percent confidence interval 1.30 to 1.63, and rated that body of evidence high quality (van Zuuren et al., Cochrane Database Syst Rev 2015, PMID 25919144).

The same review found topical metronidazole more effective than placebo, risk ratio 1.98, 95 percent confidence interval 1.29 to 3.02, from three trials, rated moderate quality. Those two numbers are not directly comparable, because the azelaic acid figure comes from participant assessments and the metronidazole figure from physician assessments. On the direct question of which of the two is better, the review states that results from three studies were contradictory. An earlier systematic review of 29 studies had also found azelaic acid more effective than placebo, odds ratio 2.45, 95 percent confidence interval 1.82 to 3.28, while noting that study quality was generally poor (van Zuuren et al., J Am Acad Dermatol 2007, PMID 17190628).

The registration trials behind the 15 percent foam give a sense of the effect size in absolute terms. Two 12 week vehicle controlled trials enrolled 1,362 subjects in total, of whom 681 received the foam and 681 the vehicle, with a mean baseline count of 21.3 inflammatory papules and pustules. In the first trial 32.1 percent on foam reached investigator assessed success against 23.4 percent on vehicle; in the second, 43.4 percent against 32.5 percent. Mean lesion count fell by 13.2 against 10.3 in the first trial and 13.3 against 9.5 in the second.

Read the trial population before you read the result. In those foam trials 95.7 percent of participants were White and the mean age was 50.6. In the two 15 percent gel trials, which enrolled 664 subjects in total with 333 on gel, 92.5 percent were Caucasian. Rosacea in Fitzpatrick type III and IV skin, which describes most readers in Vietnam, is close to absent from the registration evidence for this ingredient. That is a gap in the data, not a claim that it works less well.

What It Does To Pigment

This is the use that brings most people to the ingredient, and it is the one with no approval behind it. The pigment story rests on the idea that azelaic acid acts on melanocytes that are already overactive rather than on normal ones. A 1991 pharmacology review described it as effective in hyperpigmentary disorders characterised by hyperactive or abnormal melanocyte function, including melasma, and reported that in patients with melasma it proved at least as effective as topical hydroquinone (Fitton and Goa, Drugs 1991, PMID 1712709).

The two most quoted head to head trials say different things and both have limits. A 24 week double blind study randomised 329 women between 20 percent azelaic acid cream and 4 percent hydroquinone cream, both used with a broad spectrum sunscreen, so roughly half received each. Azelaic acid produced 65 percent good or excellent results, and no significant treatment differences were seen on overall rating, lesion size or pigmentary intensity (Baliña and Graupe, Int J Dermatol 1991, PMID 1816137). A much later comparison of 29 women, 15 on hydroquinone and 14 on azelaic acid for two months, found a lower melasma area and severity index on azelaic acid at two months, 3.8 against 6.2, a statistically significant difference. The author immediately qualified it: this was an open trial in mild melasma and larger studies are needed before the result is conclusive (Farshi, J Cosmet Dermatol 2011, PMID 22151936).

Set against the wider review, the picture is narrower than either trial alone. The Cochrane melasma review covering 20 studies and 2,125 participants in total found azelaic acid 20 percent significantly more effective than 2 percent hydroquinone, risk ratio 1.25, 95 percent confidence interval 1.06 to 1.48, but not more effective than 4 percent hydroquinone, risk ratio 1.11, 95 percent confidence interval 0.94 to 1.32. That review also judged the quality of melasma trials generally poor and available treatments inadequate (Rajaratnam et al., Cochrane Database Syst Rev 2010, PMID 20614435).

Pigment is also not one thing. A pilot study of 50 women of South East Asian ancestry with dermoscopically confirmed solar lentigines, treated twice daily for two or three months and assessed by reflectance spectrophotometry and image analysis, reported that a 20 percent azelaic acid formulation appeared inefficacious on those lesions, while a stabilised soy extract showed a modest lightening effect. The authors concluded that topical whitening agents control focal epidermal hyperpigmentation better when the extra melanin reflects modest functional overactivity of melanocytes (Hermanns et al., Dermatology 2002, PMID 12077522). It was a small pilot split across three formulations, so it is a signal about which pigment problem responds, not a verdict.

This page stops here on purpose. Melasma is a condition with its own causes, its own light problem and its own long list of trialled treatments, and repeating that here would only split it in half. The melasma guide covers the condition, including what the evidence says about the alternatives and why it comes back. This page covers the ingredient.

20 Percent, 15 Percent, Gel or Cream

People search for azelaic acid gel 20, and the format and the strength are not as interchangeable as that phrase makes them sound. Querying the openFDA National Drug Code directory on the active_ingredients.name field for azelaic acid, using the data refresh dated 4 August 2026, returned 29 records. Nine of those are bulk ingredient entries for compounding rather than finished products. Of the 20 finished products, this is how they split by marketing category:

Marketing category	Count	What that means
NDA	2	Approved new drug application. The 20 percent cream and the 15 percent foam.
NDA authorised generic	1	Sold under an existing approved application. A 15 percent gel.
ANDA	5	Approved generic of an approved product. All five are 15 percent gels.
OTC monograph	10	Marketed under a monograph. Not an individually approved product.
Unapproved drug other	2	Listed with the regulator. Explicitly not approved.

Eight of those 20 sit under an approved application. The other 12 are listed, which is a registration step, not an approval. Being findable in a national drug database says a company filed paperwork, and nothing at all about whether a regulator reviewed the evidence for that product.

Read across the strengths and the formats and the search term falls apart. Among the eight approved application records, exactly one is 20 percent and it is a cream. The other seven are all 15 percent, and all are gels or a foam. No 20 percent gel appears under an approved application in that directory. This does not mean a 20 percent gel is fake or unsafe. It means the US approval package that people cite when they discuss azelaic acid gel 20 does not cover a 20 percent gel, and any specific product needs its own national registration checked instead.

A registration record is not a specification either

Two of the listings in that directory are worth looking at closely, because they show what a filed record can look like. A product branded 10 percent azelaic acid acne cream, NDC 84148-009, marketing category unapproved drug other, lists azelaic acid in its active ingredients at 0.015 grams per 100 grams. The 10 grams per 100 grams figure on that record belongs to madecassoside. A companion product branded 15 percent azelaic acid acne cream, NDC 84148-010, lists azelaic acid at 0.03 grams per 100 grams, and the 15 grams per 100 grams figure belongs to a dandelion leaf ingredient.

That describes what was filed, not what is physically in the tube, which is not something a database can tell anyone. The point stands either way: the percentage printed on a box is a marketing claim until some document ties it to a measured content, and the number in a brand name can attach to a completely different ingredient in the paperwork behind it.

Vehicle is the other half of the question. A gel base and a cream base at the same percentage are not automatically equivalent, because the base changes how much active reaches the skin and how much irritation comes with it. No bioequivalence study comparing a 20 percent gel to the 20 percent cream was found in the sources searched for this page.

Compared To Other Actives

Every row below is a comparison that was actually run, with the population and the certainty attached. Nothing here is inferred from mechanism.

Compared with	In	What the appraisal found	Certainty
Benzoyl peroxide	Acne	Azelaic acid probably worse, RR 0.82, CI 0.72 to 0.95, one study, 351 participants	Moderate
Tretinoin	Acne	Probably little or no difference, RR 0.94, CI 0.78 to 1.14, one study, 289 participants	Moderate
Clindamycin	Acne	May be little or no difference, RR 1.13, CI 0.92 to 1.38, one study, 229 participants	Low
Adapalene	Acne	Uncertain, one study, 55 participants	Very low
Niacinamide	Acne	No head to head trial found. The four nicotinamide studies in the same review were against clindamycin or erythromycin and none measured the participant global assessment	Not assessed
Hydroquinone 2 percent	Melasma	Azelaic acid 20 percent more effective, RR 1.25, CI 1.06 to 1.48	Trials rated generally poor
Hydroquinone 4 percent	Melasma	No significant difference, RR 1.11, CI 0.94 to 1.32	Trials rated generally poor
Metronidazole	Rosacea	Both beat placebo. Results from three studies were contradictory on which of the two is more effective	High for azelaic acid vs placebo

The acne rows come from the 2020 Cochrane review (PMID 32356369), the melasma rows from the 2010 Cochrane review (PMID 20614435), the rosacea row from the 2015 Cochrane review (PMID 25919144). Confidence intervals are 95 percent throughout.

The niacinamide row is the one that surprises people. Both ingredients appear in the same Cochrane review, so the absence of a comparison is not an oversight of searching. What that review found for nicotinamide was four studies against topical antibiotics, none of which reported the outcome the review had chosen as primary. The niacinamide guide goes through what its own trials did measure. For the retinoid side of the comparison, the retinol guide and tretinoin versus retinol cover where the prescription and over the counter forms differ.

What The Labels Report Going Wrong

The reported rates differ a lot between the 20 percent cream and the 15 percent gel, and the reason is worth noting before the numbers: they come from different trials, in different conditions, with different reporting conventions, so they cannot be read as a strength comparison.

The 20 percent cream label reports the most common adverse reactions in US trials as pruritus, burning, stinging and tingling, occurring in approximately 1 to 5 percent of patients, and describes them as generally mild and transient. Erythema, dryness, rash, peeling, irritation, dermatitis and contact dermatitis were reported in less than 1 percent.
The 15 percent gel label reports burning, stinging or tingling in 29 percent, pruritus in 11 percent, scaling, dry skin or xerosis in 8 percent, and erythema or irritation in 4 percent. Those percentages are out of the 457 subjects who received the gel across three trials, not the 788 total who were monitored, which includes the 331 on vehicle.
In the gel trials, scaling, dry skin or xerosis was reported more often on the vehicle than on the gel, 46 of 331 against 36 of 457. Not every uncomfortable thing that happens during treatment is caused by the active.
In an active controlled trial within that programme, 19.4 percent, or 24 of 124, reported at least one of a listed group of local reactions on azelaic acid gel at 15 weeks, against 7.1 percent, or 9 of 127, on the comparator gel. That figure counts anyone with any one of burning, stinging or tingling, dryness, tightness or scaling, itching, or erythema, irritation or redness. It is not the rate of any single reaction.
The 15 percent foam label reports application site pain in 6.2 percent against 1.5 percent on vehicle, and application site pruritus in 2.5 percent against 0.3 percent. Application site dryness and erythema were both at or below the vehicle rate.

The warning that matters most for readers here. All three approved US azelaic acid labels carry a version of it. The 20 percent cream and the 15 percent gel report isolated reports of hypopigmentation after use of azelaic acid; the 15 percent foam drops the word isolated and reports that there have been reports of it. All three then say the same thing: because azelaic acid has not been well studied in patients with dark complexions, those patients should be monitored for early signs of hypopigmentation, and the cream and foam labels both instruct that abnormal changes in skin colour be reported to a doctor. An ingredient used to even out pigment carrying a warning about losing pigment is exactly the kind of thing a product page will not tell you.

The labels also list worsening of asthma, and the 15 percent gel label adds post marketing hypersensitivity reactions including angioedema, eye swelling, facial swelling, dyspnea and urticaria. Contact with the eyes and mucous membranes is addressed on all three. The aerosol foam adds a flammability warning about its propellant. None of that is a reason to be frightened of a common ingredient, and all of it is a reason to read the leaflet in the box rather than a summary of it.

Where The Evidence Stops

Mechanism. Both label families state the mechanism is unknown for their indication. The tyrosinase and antimicrobial findings behind the popular explanation are in vitro, and the 20 percent cream label says their clinical significance is unknown.
Skin type. The registration trials for the rosacea products were 92.5 percent and 95.7 percent white. No trial in a predominantly Vietnamese or Southeast Asian population was found for any of the three approved indications in the sources searched here.
Head to head against niacinamide. Not run, at least not in the Cochrane review that assessed both ingredients for acne.
The 20 percent gel format. No approved application covers it in the US directory, and no bioequivalence study against the 20 percent cream was found.
Combination with topical peptides. No trial of azelaic acid alongside a topical peptide was found in the searches run for this page. Azelaic acid is a small dicarboxylic acid, not a peptide, and the two sit in different evidence categories.
Long term use. The rosacea registration trials ran 12 weeks. The longest melasma comparison cited here ran 24 weeks. What happens over years is not in this evidence base.

One thing this page cannot settle is the regulatory status of azelaic acid products in Vietnam. Whether a given strength is sold over the counter or requires a prescription, and whether a specific brand holds a current Vietnamese registration, could not be verified from any database queried for this page, all of which are United States sources. A pharmacist can answer both questions in about a minute.

The Short Version

Azelaic acid is a dicarboxylic acid that is also a normal dietary and endogenous compound. About 4 percent of a topical dose is absorbed, and the label reports that plasma and urine levels afterwards are not significantly different from baseline.
In the United States the 20 percent product approved is a cream, for mild to moderate inflammatory acne. The 15 percent products approved are gels and a foam, for the papules and pustules of mild to moderate rosacea. Melasma is not an approved indication.
Rosacea is its strongest grade: high quality Cochrane evidence that it beats placebo, RR 1.46, CI 1.30 to 1.63, though three studies disagreed on whether it or metronidazole is better.
For acne it sits behind benzoyl peroxide on the graded evidence, RR 0.82, CI 0.72 to 0.95, from a single trial of 351 participants, and roughly level with tretinoin. The 2024 AAD guideline gives it a conditional recommendation, not a strong one.
For melasma it beat 2 percent hydroquinone and matched 4 percent hydroquinone in the Cochrane review's own comparison, in a literature that same review called generally poor.
Against niacinamide there is no head to head trial in the review that covered both ingredients.
Every approved US azelaic acid label warns about isolated hypopigmentation and tells doctors to monitor patients with dark complexions, which is the line most product pages leave out.
A product being listed in a drug database is not the same as it being approved. Eight of the 20 finished azelaic acid products in the US directory sit under an approved application.

Frequently Asked Questions

What is azelaic acid gel 20 used for?+

Be careful with the strength and the format together, because in the United States drug listing they do not pair the way the search term suggests. The one azelaic acid product there carrying a 20 percent strength under an approved application is AZELEX, a cream, approved for the topical treatment of mild to moderate inflammatory acne vulgaris (application NDA 020428). Every azelaic acid product in that listing that is a gel or a foam under an approved application is 15 percent, and those are approved for the inflammatory papules and pustules of mild to moderate rosacea. Querying the openFDA National Drug Code directory on the active_ingredients.name field for azelaic acid on 5 August 2026 returned 29 records and no 20 percent gel under an approved application. A 20 percent gel sold elsewhere in the world is not covered by those US approvals, and its own national registration is the thing to check.

Does azelaic acid work for melasma?+

The trial record is real but mixed, and it depends on which comparison you look at. A Cochrane review of 20 randomised studies covering 2,125 participants in total found azelaic acid 20 percent significantly more effective than 2 percent hydroquinone at lightening melasma, risk ratio 1.25, 95 percent confidence interval 1.06 to 1.48, but not more effective when compared with 4 percent hydroquinone, risk ratio 1.11, 95 percent confidence interval 0.94 to 1.32 (Rajaratnam et al., Cochrane Database Syst Rev 2010, PMID 20614435). The same review judged the quality of melasma trials generally poor. Melasma is not an approved indication on any of the US azelaic acid labels, so that use is off label there. The condition itself, including what else has been trialled for it, is covered on the melasma guide rather than repeated here.

Azelaic acid vs niacinamide, which has better evidence?+

They have not been put head to head in the review that covers both. A 2020 Cochrane review examined azelaic acid, salicylic acid, nicotinamide, sulphur, zinc and alpha hydroxy acid for acne across 49 trials with 3,880 reported participants in total. It produced graded comparisons for azelaic acid against benzoyl peroxide, tretinoin, clindamycin and adapalene, but for nicotinamide it found only four studies, all against clindamycin or erythromycin, and none of them measured the participant global assessment of improvement at all (Liu et al., Cochrane Database Syst Rev 2020, PMID 32356369). So the honest answer is that azelaic acid has been measured against more comparators on the outcome that matters, not that it beat niacinamide in a trial. No such trial was found in that review.

Is azelaic acid safer than a retinoid for pigment and acne?+

Safer is not a word the evidence supports on its own. On effectiveness for acne, the 2020 Cochrane review found probably little or no difference between azelaic acid and tretinoin on participant assessed response, risk ratio 0.94, 95 percent confidence interval 0.78 to 1.14, from one study of 289 participants, moderate certainty (PMID 32356369). On tolerability, a 1997 review article on the 20 percent cream described it as broadly comparable in efficacy to 0.05 percent tretinoin, 5 percent benzoyl peroxide and 2 percent erythromycin, but less irritating than tretinoin and benzoyl peroxide (Gibson, Dermatol Nurs 1997, PMID 9392765). That is a review article summing up, not a trial that measured irritation head to head. The approved US azelaic acid labels do carry their own warnings, including isolated reports of hypopigmentation and a specific instruction to monitor patients with dark complexions. Which agent suits a particular person is a dermatologist or pharmacist question, not something a page can answer.

Can azelaic acid be used during pregnancy?+

That is a doctor question, and the label is the honest place to start rather than a blog. The current US prescribing information for the 15 percent foam states that azelaic acid is minimally absorbed systemically after topical use and that maternal use is not expected to result in fetal exposure to the drug. It then reports animal data: oral dosing during organogenesis produced embryofetal toxicity in rats, rabbits and cynomolgus monkeys at doses the label puts at 162, 19 and 65 times the maximum recommended human dose on a body surface area basis, with maternal toxicity at those doses and no malformations observed. Those are oral animal doses and do not translate into a human topical figure. Anyone who is pregnant or breastfeeding should take the decision with the clinician who knows their case.

Is Ezanic gel 20 the same thing as azelaic acid?+

Ezanic gel 20 is a brand name people search alongside azelaic acid 20 percent, and brand searches like it are usually a route to the ingredient rather than to a distinct molecule. What could not be verified here is the specific product: no composition, manufacturing or registration record for that brand was retrievable from the databases queried for this page, which were the openFDA drug label and National Drug Code endpoints and PubMed, all of which cover the United States rather than Vietnam. So the ingredient is well documented and the individual box is not, at least not from here. The pharmacist selling it can show the Vietnamese registration number, and that is the check worth doing.

References

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 Syst Rev. 2020;5(5):CD011368. 49 trials, 3,880 reported participants, Europe, Asia and the USA. PMID 32356369
van Zuuren EJ, Fedorowicz Z, Carter B, van der Linden MM, Charland L. Interventions for rosacea. Cochrane Database Syst Rev. 2015;(4):CD003262. 106 studies, 13,631 participants, trials restricted to moderate to severe rosacea. PMID 25919144
Rajaratnam R, Halpern J, Salim A, Emmett C. Interventions for melasma. Cochrane Database Syst Rev. 2010;(7):CD003583. 20 studies, 2,125 participants, 23 treatments. PMID 20614435
Reynolds RV, Yeung H, Cheng CE, et al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol. 2024;90(5):1006.e1-1006.e30. United States guideline, 18 recommendations. PMID 38300170
van Zuuren EJ, Gupta AK, Gover MD, Graber M, Hollis S. Systematic review of rosacea treatments. J Am Acad Dermatol. 2007;56(1):107-115. 29 studies. PMID 17190628
Baliña LM, Graupe K. The treatment of melasma. 20% azelaic acid versus 4% hydroquinone cream. Int J Dermatol. 1991;30(12):893-895. 24 weeks, 329 women randomised between the two creams, Buenos Aires. PMID 1816137
Farshi S. Comparative study of therapeutic effects of 20% azelaic acid and hydroquinone 4% cream in the treatment of melasma. J Cosmet Dermatol. 2011;10(4):282-287. Open trial, 29 women, Tehran. PMID 22151936
Hermanns JF, Petit L, Piérard-Franchimont C, Paquet P, Piérard GE. Assessment of topical hypopigmenting agents on solar lentigines of Asian women. Dermatology. 2002;204(4):281-286. Pilot study, 50 women of South East Asian ancestry. PMID 12077522
Nazzaro-Porro M. Azelaic acid. J Am Acad Dermatol. 1987;17(6):1033-1041. Review of in vitro and tissue culture findings. PMID 2963038
Fitton A, Goa KL. Azelaic acid. A review of its pharmacological properties and therapeutic efficacy in acne and hyperpigmentary skin disorders. Drugs. 1991;41(5):780-798. PMID 1712709
Graupe K, Cunliffe WJ, Gollnick HP, Zaumseil RP. Efficacy and safety of topical azelaic acid (20 percent cream): an overview of results from European clinical trials and experimental reports. Cutis. 1996;57(1 Suppl):20-35. Lead author from the developing company. PMID 8654128
Gibson JR. Azelaic acid 20% cream (AZELEX) and the medical management of acne vulgaris. Dermatol Nurs. 1997;9(5):339-344. PMID 9392765
Draelos ZD, Elewski BE, Harper JC, et al. A phase 3 randomized, double-blind, vehicle-controlled trial of azelaic acid foam 15% in the treatment of papulopustular rosacea. Cutis. 2015;96(1):54-61. PMID 26244354
AZELEX (azelaic acid) cream, 20%, United States prescribing information, Almirall LLC, NDA 020428. Indications, clinical pharmacology, adverse reactions, warnings and precautions read from the label record. open.fda.gov
Azelaic acid gel, 15%, United States prescribing information, NDA 021470. Indications with limitations of use, clinical studies and adverse reactions tables read from the label record. open.fda.gov
FINACEA (azelaic acid) Foam, 15%, United States prescribing information, LEO Pharma Inc, NDA 207071. Clinical studies, adverse reactions, warnings and pregnancy sections read from the label record. open.fda.gov
US Food and Drug Administration, openFDA National Drug Code directory. Queried on the active_ingredients.name field for azelaic acid, returning 29 records, with the marketing_category, dosage_form and active_ingredients.strength fields read per product. Data refresh dated 4 August 2026, queried 5 August 2026. open.fda.gov

Note on sourcing: every figure on this page was read from the abstract or the database field named beside it, not from a secondary summary. Trial totals are given as totals and the per arm numbers separately where the source reported them. Where a result is restricted to a country, a condition severity or a trial population, that restriction is stated in the same sentence as the number. Where a source qualified its own finding, the qualification is carried with it. In vitro, tissue culture and animal findings are labelled as such and are never converted into human figures. No figure for the Vietnamese regulatory status or market of azelaic acid is quoted here, because no source covering it was retrievable.