Only a handful of places left for our September 2026 cohort. Applications close soonApply now →

MSTA
Your future
starts here.

Azelaic acid

Also known as: azelaic, azelaic acid cream, azelaic acid gel, Finacea

Azelaic acid is a topical dicarboxylic acid used in specific medicinal formulations for acne and papulopustular rosacea, with narrower off-label evidence for melasma and post-inflammatory hyperpigmentation. Results depend on the finished product and indication; direct human pregnancy and breastfeeding outcome data are sparse.

Evidence status

Moderate

Strongest for specific prescription formulations in papulopustular rosacea, moderate for acne. Melasma and PIH evidence is limited and formulation-specific. Low systemic exposure explains cautious clinical selection in pregnancy, but direct human outcome data are far too sparse for a proven-safe claim.

What azelaic acid is, and the forms available#

Azelaic acid is a dicarboxylic acid — a different chemistry from the alpha and beta hydroxy acids it is usually filed alongside. In the UK it is used in specific licensed medicinal formulations for acne and papulopustular rosacea, with narrower off-label evidence in melasma and post-inflammatory hyperpigmentation.

The evidence belongs to particular finished products, at particular strengths, in particular indications. It does not travel to every cosmetic that lists azelaic acid on the back of the bottle, and the finished formulation rather than the number on the front is what a recommendation rests on.[16]

Use of azelaic acid in aesthetic practice#

Finacea 15% gel and Skinoren 20% cream are both prescription-only medicines. Finacea is licensed for facial papulopustular acne and papulopustular rosacea; Skinoren for acne vulgaris.[1, 2] You can discuss azelaic acid with a client and recommend that she be assessed for it, but starting a licensed strength is a prescriber’s decision.

Cosmetic products and the medicines boundary

Lower-strength azelaic acid does appear in cosmetics, and where the boundary sits is less tidy than commonly stated. MHRA borderline guidance sets no fixed 10%, 15% or 20% cutoff; classification turns on the claims made, the presentation, the intended purpose and the mode of action.[4]

A 10% cosmetic serum is therefore not lawful by virtue of its percentage, and it does not inherit the trial evidence built on the 15% and 20% medicines.

Contraindications and cautions#

Pregnancy and breastfeeding

Azelaic acid is the active most often reached for when a client is pregnant and a retinoid stops. It is a defensible choice, and what underpins it is exposure rather than outcomes. Systemic exposure from topical application is low.[1, 12] Oral animal studies found no teratogenicity, but did report embryotoxicity alongside maternal toxicity at high exposure, with no-effect levels around 3–32 times the maximum recommended human dose by body surface area.[1, 2, 11, 12]i

Adequate product-specific safety in pregnancy has not been established, and the decision belongs to the prescriber in any event, since the strengths in question are medicines.

Breastfeeding is thinner still. No measured human-milk or breastfed-infant outcome study was located, and the low-risk language in the reference sources is an exposure-based inference. The advice attached to it is to avoid breast and nipple application and infant contact.[1, 2, 13]i

Compromised skin barrier

Local irritation is a recognised effect and is frequently treatment-limiting.[1, 2, 9, 10] The product information also notes that azelaic acid penetrates damaged skin faster than intact skin, which is exactly the wrong direction for a client who has arrived with a barrier that is already compromised.

Clinical uses and the evidence behind them#

Papulopustular rosacea

This is the strongest indication. The Cochrane vehicle-controlled comparison covered 1,179 participants and carried high GRADE certainty, and BAD guidelines give a strong recommendation for azelaic acid, ivermectin or metronidazole as first-line topical options.[1, 6, 7]

The phenotype is the ceiling. Both the evidence and the licence concern papulopustular rosacea — the papules and the pustules. Flushing, persistent erythema alone, telangiectasia, phymatous change and ocular rosacea sit outside what has been established. A client with a red face is not automatically a client for azelaic acid, and that distinction accounts for a good deal of the disappointing outcomes in this category.

Acne vulgaris

NICE includes topical azelaic acid at 15% or 20% in selected acne treatment and maintenance pathways, so it is a legitimate option.

Its ceiling is a comparison the trade rarely repeats. Cochrane compared azelaic acid against benzoyl peroxide and concluded that it probably leads to a worse treatment response.[1, 2, 3, 5] That is a materially different finding from an absence of superiority, and it makes azelaic acid an option chosen for other reasons — usually tolerability, or a pregnancy context — rather than an equal alternative to benzoyl peroxide.

Melasma

Off-label, and the evidence is old, heterogeneous and generally poor quality. A 20% cream outperformed 2% hydroquinone in one trial (340 randomised, 300 completing) but was not superior to 4% hydroquinone in another (329 enrolled, 243 analysed), and long-term response remained uncertain.[8]

The funding travels with the literature: the pivotal 4%-hydroquinone trial was conducted in association with Schering AG, and the review found 11 of 20 melasma trials were industry-sponsored.

Post-inflammatory hyperpigmentation

Also off-label. Small, formulation-specific trials suggest that 15–20% may improve acne-associated PIH, and the limits travel with the result: one 12-week vehicle-controlled study randomised 72 and analysed 60, predominantly phototype III, and the comparative study against tranexamic acid randomised 82 with 60 completing, had no untreated control arm, and used sunscreen throughout.[9, 10]

None of that transfers to an undiagnosed dark mark of unknown cause.

Selecting a formulation#

The decision is which finished product, not which percentage. Most of the established evidence concerns the named 15% and 20% licensed medicines, and those are prescription-only. Lower-strength evidence exists, and it is specific to the formulation tested: a double-blind randomised trial compared a 10% azelaic-acid nanocrystal in-situ hydrogel — an engineered delivery system built to compensate for the lower concentration — with a 20% cream over eight weeks, and the hydrogel performed comparably.[16]

That result belongs to the delivery system rather than to the number. A retail 10% serum is not the same object as the hydrogel that was trialled, and neither is interchangeable with a licensed 15% or 20% medicine. Where a cosmetic product is what is available, its performance is a property of that finished formulation and has not been established by the trials run on the medicines.

Adverse effects and their management#

Expected local effects

Burning, itching, pain, redness, dryness and exfoliation are the recognised local effects, and they are common enough to end a course: 11 participants discontinued azelaic acid because of side effects in one comparative trial.[1, 2, 9, 10]

The reported purge

No primary evidence was located that a purging phase demonstrates azelaic acid is working.[no source found]

The position that follows is narrower than calling the purge a myth. Irritation is an adverse effect, and nothing in the primary literature connects it to efficacy, so a client whose skin worsens after starting is one to reassess rather than one to reassure that the reaction is progress.

Reducing, stopping and referring

Where a licensed strength is in use, the decision to reduce or stop it sits with the prescriber who started it. Where the skin has worsened rather than settled, that is information rather than a phase, and it belongs back with that prescriber.

Referral and scope boundaries#

The strengths carrying the evidence in this category are medicines, which makes referral a routine part of competent practice here rather than a limitation of it. Referral is indicated in four situations:

  • A client who needs a licensed strength. The 15% and 20% formulations are prescription-only, so the route to them is an assessment rather than a recommendation.[1, 2]
  • Pregnancy and breastfeeding.
  • Pigmentation of unclear cause. The pigment evidence is acne-associated PIH and melasma; an undiagnosed dark mark is a diagnostic question first.
  • Rosacea beyond papules and pustules. Flushing, telangiectasia, phymatous change and ocular rosacea sit outside both the licence and the evidence.

Photoprotection was part of the pigment regimens that were studied, and it continues alongside a prescriber without requiring one.

Mechanism of action#

Azelaic acid is described as antibacterial, anti-keratinising, anti-inflammatory and a tyrosinase inhibitor. Those proposed actions draw on a mixture of clinical, purified-enzyme, cultured-cell and animal evidence, and no single molecular story fully explains the clinical outcomes.[1, 2, 14, 15]i

The clinical benefit in pigmentation is better established than any proposed explanation for it — an acceptable position to hold, and a more honest one than picking a mechanism because it sounds tidy.

Commonly misstated claims#

Four statements circulate widely in the trade. Each is set out below with what the primary literature was found to support.

“Azelaic acid is the pregnancy-safe active.”

It is the commonly chosen one, on the basis of low systemic exposure and reassuring animal data. The original licensing programme documented two exposed pregnancies, both reported as apparently healthy, with full term explicitly documented for one — and two documented exposures is not a safety dataset.[1, 2, 11, 12]i

Supported statement: azelaic acid is chosen in pregnancy because exposure is low and the animal signal is reassuring, not because human outcomes have been studied and found safe.

“Only 3.6% of it is absorbed.”

The figure derives from urinary recovery in six healthy men after a single large-area application of one 20% cream. It describes that measurement, not a universal rate across products, sites, quantities or skin conditions.[1, 12]

Supported statement: systemic exposure from topical azelaic acid is low, and the single percentage attached to it comes from one small study of one cream.

“It works by inhibiting tyrosinase.”

In the purified-enzyme work usually cited, direct inhibition was weak, and observed only at cytotoxic concentrations. A concentration that kills the cell is not a plausible mechanism for a cosmetic effect on living skin.[15]

Supported statement: the pigment effect is better established than any explanation for it, and tyrosinase inhibition is not a usable account of it.

“It repairs the barrier and controls oil.”

One 12-week trial of a 15% gel measured transepidermal water loss, hydration and sebum, and found no between-group advantage over vehicle on any of them.[9]

Supported statement: barrier-repair and oil-control claims for azelaic acid are unestablished.

Areas of remaining uncertainty#

  • Whether cosmetic-strength azelaic acid does anything comparable to the licensed medicines, which leaves the finished formulation rather than the percentage as the only basis a recommendation can rest on.
  • Human pregnancy and breastfeeding outcomes, which barely exist as data — so the defensible language remains “commonly chosen” rather than “proven safe”.
  • Which mechanism accounts for the pigment effect. Until one is established, the effect is described rather than explained.
  • Long-term melasma response, which the review left unresolved, leaving no duration of benefit that can be quoted to a client.
  • How much of the PIH result belongs to azelaic acid and how much to the sunscreen used alongside it, which makes photoprotection part of the regimen that was studied rather than an optional addition to it.

Frequently asked questions#

Can azelaic acid be recommended to a client?

It can be discussed, and a client can be referred for assessment. The strengths with evidence behind them are prescription-only in the UK, so supplying or directing the use of those is a prescriber’s decision.[1, 2]

Is a 10% cosmetic serum equivalent to a licensed product?

No. The 10% product with a trial behind it was a nanocrystal in-situ hydrogel, an engineered delivery system, compared with a 20% cream over eight weeks.[16] A retail serum at the same percentage is a different object, and the comparison does not carry across to it.

How long before a client sees a result?

Weeks to months. The vehicle-controlled study in acne-associated PIH measured its outcomes at twelve weeks,[9, 10] which makes early expectation-setting more useful than later explanation.

References#

Each source is graded by evidence tier. Tier 4 material (manufacturer documents, expert consensus, practitioner experience) is useful for protocol and context, and is never presented as equivalent to independent clinical evidence.

  1. LEO Laboratories Limited. Finacea 15% Gel: Summary of Product Characteristics. Electronic Medicines Compendium. Text revised 13 July 2023.Tier 1Supports: UK prescription status, 15% formulation, acne and papulopustular-rosacea indications, adverse effects, and the note that absorption is faster through damaged than intact skin. Oral animal studies found no teratogenicity but reported embryotoxicity with maternal toxicity at high exposure; animal NOAELs correspond to roughly 3–32× the maximum recommended human dose by body surface area.
  2. LEO Laboratories Limited. Skinoren 20% Cream: Summary of Product Characteristics. Electronic Medicines Compendium. Last updated 12 September 2023.Tier 1Supports: UK prescription status, 20% formulation, acne-only indication, common local reactions, uncommon depigmentation, pregnancy caution, and modelled — not measured — lactation exposure.
  3. National Institute for Health and Care Excellence. Acne vulgaris: management. NICE guideline NG198.Tier 1Supports: Defines topical azelaic acid as 15% or 20% and includes it in selected acne treatment and maintenance pathways for England.
  4. Medicines and Healthcare products Regulatory Agency. Borderline products: how to tell if your product is a medicine.Tier 1Supports: UK classification turns on claims, presentation, intended use and pharmacological properties. The guidance states no fixed azelaic-acid concentration boundary.
  5. 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;(5):CD011368.Tier 1Supports: Compared with benzoyl peroxide, azelaic acid PROBABLY LEADS TO A WORSE TREATMENT RESPONSE — not merely an absence of superiority. Certainty for the acne comparisons was moderate to low.Funding / interest: The review notes extensive pharmaceutical support across the underlying trial evidence.
  6. van Zuuren EJ, Fedorowicz Z, Carter B, van der Linden MMD, Charland L. Interventions for rosacea. Cochrane Database of Systematic Reviews. 2015;(4):CD003262.Tier 1Supports: Vehicle-controlled rosacea efficacy across 1,179 participants, predominantly papulopustular. The vehicle comparison carried HIGH GRADE certainty. Response duration was incompletely reported.Funding / interest: 66 of 106 included studies stated funding, mostly pharmaceutical. This describes the underlying evidence base, not authorship of the review.
  7. Hampton PJ, Berth-Jones J, Duarte Williamson CE, et al. British Association of Dermatologists guidelines for the management of people with rosacea 2021. British Journal of Dermatology. 2021;185(4):725–735.Tier 1Supports: Strong recommendation for azelaic acid, ivermectin or metronidazole as first-line topical options in papulopustular rosacea, with irritancy discussed.Funding / interest: No direct funding. Several authors disclosed relationships with pharmaceutical and skincare companies.
  8. Rajaratnam R, Halpern J, Salim A, Emmett C. Interventions for melasma. Cochrane Database of Systematic Reviews. 2010;(7):CD003583.Tier 1Supports: Old, heterogeneous, generally poor-quality melasma trials. 20% cream outperformed 2% hydroquinone (340 randomised, 300 completing) but NOT 4% hydroquinone (329 enrolled, 243 analysed). Long-term response remained uncertain.Funding / interest: The pivotal 4%-hydroquinone trial (Baliña 1991) was conducted in association with Schering AG — the same manufacturer disclosed on the absorption study at source 12. The review found 11 of 20 melasma trials were industry-sponsored.
  9. Shucheng H, Zhou X, Du D, Li J, Yu C, Jiang X. Effects of 15% azelaic acid gel in the management of post-inflammatory erythema and post-inflammatory hyperpigmentation in acne vulgaris. Dermatology and Therapy. 2024;14(5):1293–1314.Tier 2Supports: Twelve-week vehicle-controlled study, 72 randomised and 60 analysed, predominantly phototype III. Notable attrition, retrospective registration, early local effects, and NO between-group advantage for TEWL, hydration or sebum.Funding / interest: Funded by the National Natural Science Foundation of China; formulations supplied by Kelun Pharma. Authors declared no conflicts.
  10. Sobhan M, Alizadeh P, Sheykhi N. A comparative study of 20% azelaic acid cream versus 5% tranexamic acid solution for postinflammatory hyperpigmentation in patients with acne vulgaris: a single-blinded randomized clinical trial. Journal of Research in Medical Sciences. 2023;28:18.Tier 2Supports: Active-comparator acne-PIH study, 82 randomised and 60 completing, with 11 azelaic-acid discontinuations for side effects, sunscreen co-intervention throughout, and no untreated control arm.
  11. US Food and Drug Administration, Center for Drug Evaluation and Research. Finacea (azelaic acid) gel 15%, NDA 21-470: Medical Review, Part 2. 2002.Tier 1Supports: Two pregnancies exposed to active 15% gel across the original clinical programme. Both outcomes reported as apparently healthy, with full term explicitly documented for one. Far too little to establish fetal safety.
  12. Täuber U, Weiss C, Matthes H. Percutaneous absorption of azelaic acid in humans. Experimental Dermatology. 1992;1(4):176–179.Tier 3Supports: The widely quoted 3.6% absorption estimate derives from urinary recovery in six healthy men after a single large-area application of one 20% cream.Funding / interest: Study affiliation was the Institute of Pharmacokinetics, Schering AG — the manufacturer associated with the product studied.
  13. National Institute of Child Health and Human Development. Azelaic acid. Drugs and Lactation Database (LactMed). Updated 15 March 2026.Tier 4Supports: States that topical use has not been studied in breastfeeding. The low-risk assessment is inferred from exposure, with no breast or nipple application and no infant contact advised.
  14. Coda AB, Hata T, Miller J, et al. Cathelicidin, kallikrein 5, and serine protease activity is inhibited during treatment of rosacea with azelaic acid 15% gel. Journal of the American Academy of Dermatology. 2013;69(4):570–577.Tier 3Supports: Cultured human keratinocyte, mouse-skin and open-label human findings on the rosacea inflammatory pathway. 60 entered, 55 completed, 49 analysed. Contains NO pigment data and does not support a melanogenesis claim.Funding / interest: Supported in part by an investigator-initiated Bayer/Intendis grant; several authors disclosed consultancy or research relationships.
  15. Schallreuter KU, Wood JW. A possible mechanism of action for azelaic acid in the human epidermis. Archives of Dermatological Research. 1990;282(3):168–171.In vitroTier 3Supports: Purified-enzyme and in-vitro work finding only weak direct tyrosinase inhibition, and at CYTOTOXIC concentrations. Not a human pigmentation outcome study.
  16. 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(5):567.Tier 2Supports: REFUTES THE CLAIM THAT NOTHING BELOW 15% HAS BEEN TRIALLED. A double-blind randomised trial comparing a 10% azelaic-acid NANOCRYSTAL in-situ hydrogel with a 20% azelaic-acid cream, about 1 g twice daily for eight weeks. At week eight the hydrogel reached a 36.51% success rate against 30.37% for the cream, with total inflammatory lesions down 39.15% against 33.76%. SCOPE LIMIT THAT MATTERS MORE THAN THE RESULT: this is one experimental nanocrystal delivery system, engineered specifically to compensate for the lower concentration. It says nothing about an ordinary retail 10% serum.Funding / interest: One author, Sandra Miočić, is affiliated with R&D, PLIVA Croatia Ltd., a Teva Group member.

Continue learning with MSTA#

Skinipedia is written by the educators at MSTA, the medic-led skincare training academy in Liverpool.