Azelaic Acid

Azelaic acid is a dicarboxylic acid found naturally in grains such as wheat, rye and barley, and also produced by yeast that lives on human skin. The version used in skincare is made synthetically, which gives the consistency and purity a formulated product needs.

Despite the name it does not behave like the exfoliating acids people usually have in mind. It is not an AHA or a BHA, it does not need a low pH to work, and it does not cause the shedding or sun sensitivity associated with glycolic acid. In practice it is one of the better-tolerated actives available, which is a large part of its appeal.

On an ingredients list it appears as Azelaic Acid. Over-the-counter products in the UK typically use 10%, sometimes described as a suspension or a cream-gel, since it is poorly soluble and often sits in a formula as fine particles rather than fully dissolved. Higher strengths of 15% and 20% are available on prescription. You may also see the derivative Potassium Azeloyl Diglycinate, a more soluble, gentler relative used in lighter textures.

Its texture is worth mentioning because it surprises people: 10% azelaic products often feel slightly grainy or thick going on and can leave a faint white cast for a minute or two. That is normal and settles as it is absorbed.

It is most often chosen for skin that looks red and reactive, uneven in tone, or congested, and it is one of the few actives that addresses all three without demanding a careful tolerance-building process.

Azelaic acid works along several routes at once, which is why it appears in products aimed at quite different-looking concerns.

On tone, it interferes with tyrosinase, the enzyme that governs melanin production. Usefully, it appears to act selectively, having more effect on overactive pigment-producing cells than on normally behaving ones. In practice that means it tends to soften the look of dark marks without lightening the surrounding skin, which is a common worry with brightening ingredients.

On congestion, it has an antibacterial action against organisms associated with the look of breakouts, and it helps normalise the way cells shed inside the pore, so plugs are less likely to form. It is mild enough to keep using once things settle, which matters because congestion tends to return when treatment stops abruptly.

On the appearance of redness, it has a calming action linked to its effect on free radicals and on inflammatory signalling in the skin. This is the reason it is so often recommended for skin that looks persistently flushed. Because none of these routes involves stripping the surface, azelaic acid can usually be used daily, and often twice daily, from early on. Visible change is gradual: expect two to three months of consistent use before judging it.

Azelaic acid is unusually easy to live with, and it suits people who have found other actives too demanding.

• Strength: 10% is the standard over-the-counter figure. Higher strengths are prescription only.
• Frequency: once daily to begin with, moving to twice daily if it suits you. There is no lengthy tolerance-building process required.
• When: morning or evening. Both work, and many people use it at both ends of the day.
• Order in the routine: after cleansing and any watery serum, before moisturiser. It is thicker than most serums, so it should not go underneath something even lighter.
• Expect a texture. A slight grittiness and a brief white cast are normal with 10% suspensions. Massage it in and give it a minute.
• A mild tingle in the first week or two is common and usually fades. Persistent stinging is not, and means you should use it less often.
• Pairs well with: niacinamide, hyaluronic acid, ceramides, panthenol and gentle moisturisers. It also sits reasonably well alongside a retinoid if you separate them by time of day.
• Go carefully with: strong AHAs, BHAs and benzoyl peroxide on the same occasion.
• Sunscreen: still essential. Azelaic acid does not increase sun sensitivity, but daylight will undo any progress on the look of tone and redness.

Give it a full three months. Azelaic acid is a slow, steady ingredient rather than a dramatic one, and stopping early is the usual reason people conclude it did nothing.