Azelaic acid: what the evidence shows for redness, marks and blemishes
Azelaic acid has strong trial evidence at medicine strength for redness, blemishes and uneven tone. CSL formulation scientists explain what that means for cosmetic products at lower levels or as derivatives.
By CSL Formulation team · Evidence checked by CSL scientists
At a glance
- What it is
- A naturally occurring dicarboxylic acid, also used as the water-soluble derivative potassium azeloyl diglycinate
- Main benefits
- Less visible redness, fewer visible blemishes, more even-looking tone
- Levels tested in trials
- 15% gel and 20% cream in most trials (medicine strength); 15% in one dermocosmetic cream; derivative levels rarely disclosed
- Time to results
- 8 to 12 weeks in controlled studies
- Watch for
- Poor solubility, grittiness, stinging, and medicine status at 15–20% in many markets
01What is it?
Azelaic acid is a dicarboxylic acid made naturally by the skin yeast Malassezia and found in grains. At 15–20% it is a prescription medicine in many markets. In cosmetics it is used at lower levels, or as the more soluble derivative potassium azeloyl diglycinate.
02What it does
Azelaic acid slows melanin production, calms inflammation, normalises how skin cells shed in the pore and reduces acne-related bacteria. Over two to three months this shows as less visible redness, fewer visible blemishes and a more even-looking tone, including marks left after spots.
03The evidence
Studies below were checked against the publisher, DOI or journal record on 26 Sep 2026. We list design and size so you can judge the strength of each result.
| Study | Design | Who and how long | What it found |
|---|---|---|---|
| King et al. 2023, Journal of Cosmetic Dermatology (Wiley) Source | Systematic review with meta-analyses | 43 randomised trials of at least 6 weeks, for acne, rosacea, pigmentation and ageing | Better than vehicle for rosacea, acne and melasma at 12 weeks; often equivalent to other treatments. No eligible trials for skin ageing. |
| Al Shami 2023, Cureus (Springer Nature) Source | Systematic review and meta-analysis of randomised trials | 6 trials, 673 people with melasma, azelaic acid versus hydroquinone | Hydroquinone lowered the melasma score slightly more (mean difference 1.23 points); response, pigmentation and side effects did not differ. |
| Vladuti et al. 2024, Dermatology and Therapy (Springer Nature) Source | Open-label, randomised pilot trial | 90 people with mild to moderate acne, 84 days plus 28-day follow-up, 15% azelaic acid dermocosmetic cream vs erythromycin–zinc | Acne fell 66.5% with the azelaic acid cream versus 52.6% with erythromycin–zinc (p < 0.001), with less post-spot pigmentation. Not blinded. |
| Thiboutot et al. 2003, Journal of the American Academy of Dermatology (Elsevier) Source | Two randomised, vehicle-controlled phase III trials | 329 and 335 people with moderate papulopustular rosacea, 15% azelaic acid gel twice daily | Inflammatory lesions fell 58% vs 40% and 51% vs 39%; redness improved in 44–46% vs 28–29% with vehicle. No serious side effects. |
| Maggioni et al. 2020, Clinical, Cosmetic and Investigational Dermatology (Dove Press) Source | Open-label study, no control group | 20 adults with mild to moderate rosacea, 56 days, serum with potassium azeloyl diglycinate (level not stated) and soothing ingredients | Redness index fell from 491 to 425 and hydration rose, but with no control group and several actives the derivative's own effect is unclear. |
Azelaic acid is one of the better-evidenced actives for redness, blemishes and uneven tone, but that evidence comes mostly from 15–20% medicines. Cosmetic products at lower levels, or using potassium azeloyl diglycinate, should make modest claims such as “reduces the look of redness” and “evens the look of skin tone”, backed by testing of the finished product.
04How CSL formulation scientists use it
- Azelaic acid dissolves poorly in water (about 2.4 g/L at 20 °C), so high-level products are often suspensions that can feel gritty. CSL formulation scientists control particle size and texture, or use potassium azeloyl diglycinate for clear, water-based formats.
- Formulas are typically kept mildly acidic, around pH 4.8–5.6; stinging and itching are the most common complaints, so tolerance testing is essential.
- It pairs well with niacinamide, retinoids and soothing ingredients, and is often used where stronger lightening agents such as hydroquinone are not allowed or not wanted.
- Claims should match the form and level used: data for 15–20% azelaic acid do not transfer automatically to a low-level derivative.
05Regulatory and claims
At 15% (gel) and 20% (cream) azelaic acid is an approved medicine in the US and dispensed as a prescription product in several markets, so higher levels and acne or rosacea claims can move a product out of the cosmetic category. CSL regulatory specialists confirm the status in each target market for the exact level and form before a formula is finalised, and keep claims cosmetic: “reduces the look of redness”, not “treats rosacea”.
06Questions brands ask
Can a cosmetic contain azelaic acid?
In many markets, yes, at lower levels or as a derivative, but 15–20% products are medicines in many countries. The allowed level and claims depend on the market.
Is potassium azeloyl diglycinate as good as azelaic acid?
It is easier to formulate, but its clinical evidence is much thinner. The small studies that exist combine it with other soothing ingredients and have no control group.
Is azelaic acid as effective as hydroquinone for dark marks?
Close, but not quite. A meta-analysis of six trials found hydroquinone lowered melasma scores slightly more, with similar side effects.
07References
- King S, Campbell J, Rowe R, et al. A systematic review to evaluate the efficacy of azelaic acid in the management of acne, rosacea, melasma and skin aging. J Cosmet Dermatol. 2023;22:2650–2662. Link
- Al Shami A. Azelaic acid versus hydroquinone for managing patients with melasma: systematic review and meta-analysis of randomized controlled trials. Cureus. 2023;15:e41796. Link
- Vladuti C, Hatami A, Clément F, Mainzer C. A pilot study on the comparative efficacy and tolerability of a novel dermo-cosmetic cream with 15% azelaic acid for mild to moderate acne. Dermatol Ther (Heidelb). 2024;14:3149–3160. Link
- 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. J Am Acad Dermatol. 2003;48(6):836–845. Link
- Maggioni D, Cimicata A, Praticò A, et al. A preliminary clinical evaluation of a topical product for reducing slight rosacea imperfections. Clin Cosmet Investig Dermatol. 2020;13:299–308. Link
- Petrovici AG, Spennato M, Bîtcan I, et al. A comprehensive review of azelaic acid pharmacological properties, clinical applications, and innovative topical formulations. Pharmaceuticals (MDPI). 2025;18:1273. (Source for solubility, pH and regulatory status.) Link
Used in: Acne & oil controlHyperpigmentation & even tone
Update log
- Evidence reviewed and page published by CSL scientists
This page summarises published research for brands and formulators. It is general information, not medical advice, and results in studies depend on the full formula tested.
