"Azelaic Acid: What the 10% on the Bottle Really Means"

22 September 2026

One of the best-selling azelaic acid serums online contains no azelaic acid, and its brand page now says so in the name. We read the labels, the fine print and the studies behind four popular 10% products, and compared them with the prescription strengths the big trials actually tested. The short answer: the ingredient is well proven, but mostly at 15% and 20%, and what "10%" means depends on the bottle.

What we checked

What the label said

Azelaic acid is a natural acid found in grains such as wheat, rye and barley. It is even made by a yeast that lives on normal skin [5]. On the skin it does three useful things: it calms redness, helps clear breakouts, and slows pigment production, so dark marks can fade. Brands also sell it as gentler than many other acids, which is why people with sensitive, redness-prone skin reach for it. It has celebrity pull too: Kendall Jenner, Anua's first global ambassador, has named its azelaic serum as a favourite [8].

Here is what each label told us [7].

The Ordinary. Azelaic acid is fourth on the list, in a cream-gel with the acid suspended as tiny particles, the classic way. The brand says to keep it apart from strong acids, retinoids and vitamin C in the same routine.

Naturium. The list explains the name: there is no azelaic acid. The active is potassium azeloyl diglycinate, a water-friendly cousin made from azelaic acid and the amino acid glycine. Naturium says its own eight-week study showed less redness, but the page does not say how many people took part.

Anua. Azelaic acid is second on the list. Fourth is sodium hydroxide, a common way to get the acid to dissolve into a clear serum by turning part of it into its salt. Anua's own redness test used 20 adults for about a month at a skin-testing lab, and the fine print says the redness was caused by dryness, not a skin condition.

Paula's Choice. Azelaic acid is second, straight after water, in a cream, with 0.5% salicylic acid added for clogged pores. Almost 2,000 reviews on the brand's own site average 4.2 stars. Some people feel tingling at first.

What the evidence shows

The strong evidence for azelaic acid comes from prescription products: a 15% gel and a 20% cream.

For the bumps of rosacea, two large 12-week trials of the 15% gel included 664 adults [1, 2]. In the first trial, spots dropped by about 58% with the gel, against 40% with the same gel minus the active [2]. For melasma, a condition of dark patches on the skin, a trial of 329 women over 24 weeks found the 20% cream did about as well as 4% hydroquinone, the long-time standard treatment [3].

So the ingredient is real. The question is what happens at 10%, the usual ceiling on the beauty shelf, where there is far less published research.

There is also a chemistry catch. Azelaic acid barely dissolves in water: only about 2.4 grams per litre at 20°C [6]. A 10% product holds about 40 times more than that. This is why the classic versions are creams, with the acid suspended as particles. A clear, watery serum has to do something different: change the acid into another form, or swap it for a related molecule.

That is what Naturium and Anua do, in different ways. Research on Naturium's ingredient, potassium azeloyl diglycinate, is thin. The best-known trial involved 42 people with rosacea over four weeks at 5%, and some of its authors worked for the companies behind the ingredient [4]. Anua uses real azelaic acid, but in a partly dissolved form, and no published trial has tested whether that form works as well on skin as the prescription gel.

The verdict

For most people, The Ordinary is the one to buy: real azelaic acid, in the classic suspended form, at the lowest price here. If breakouts and bumpy texture are your main concern, Paula's Choice earns its higher price with the added salicylic acid. If your skin is sensitive and you want a light serum, Anua is a fair pick, with the caveat that its clear-serum form has not been trial-tested. We would wait on Naturium: its label is now honest, but it is not the ingredient the big studies tested, so consider it only if real acids irritate your skin.

For the real ingredient at a fair price, The Ordinary; for rosacea or melasma, ask about the prescription strengths.

Worth knowing

• Start slowly. Anua suggests once or twice a week at first, building up from there [7].
• Give it time. The prescription trials ran for 12 weeks, so judge a product at three months, not three days [1].
• Wear sunscreen daily. Fading dark marks does not work if the sun keeps making new ones.
• If you have rosacea or melasma, the 15% and 20% versions are what the big trials tested, and a doctor or dermatologist can prescribe them. This post is not medical advice.
• No sponsors. Every price is the brand's own site price.

Watch the video

See all four labels compared in the video: Azelaic Acid: What the 10% on the Bottle Really Means.

Sources

1. US FDA, prescribing information, azelaic acid gel 15% (two 12-week trials, 664 adults)
2. Thiboutot D et al., "Azelaic acid 15% gel in papulopustular rosacea", Journal of the American Academy of Dermatology, 2003
3. Baliña LM, Graupe K, International Journal of Dermatology, 1991;30:893-5
4. Berardesca E et al., Journal of Cosmetic Dermatology, 2012;11:37-41
5. DrugBank, DB00548, azelaic acid
6. Fisher Scientific / TCI, product data for azelaic acid (water solubility)
7. Ingredient lists and claims: theordinary.com, naturium.com, anua.com, paulaschoice.com, checked 22 September 2026
8. NewBeauty, Kendall Jenner named Anua's first global ambassador, 1 June 2026

Every claim above is sourced in the text. Prices are what we paid, on the date shown. We buy what we test; nothing is gifted, and nothing is sponsored.