Azelaic acid

Most of what this site writes about pregnancy is a list of things to set aside. This is one of the few pages that goes the other way, which is worth saying because a reader who has just been told to stop using half their bathroom shelf deserves to know what is left.

What it is

Azelaic acid is a nine-carbon dicarboxylic acid. It occurs naturally in wheat, rye and barley, and it is produced on human skin by Malassezia, a yeast that lives there on everyone. What goes into a tube is manufactured rather than extracted, but it is not a molecule your body is meeting for the first time.

That grain origin causes an occasional worry that is worth closing immediately: it is not gluten. Gluten is a protein, azelaic acid is a small acid molecule, and neither the source nor the manufacturing carries protein into the product.

What it does

More things than most actives, which is the reason it appears in prescriptions for several unrelated conditions.

It is antibacterial against the organisms involved in acne, it dampens inflammation, it slows the overproduction of keratin that blocks pores, and it inhibits tyrosinase, the enzyme that makes pigment. That last property is why it turns up in treatments for melasma and post-inflammatory marks as well as for spots.

Clinical work concentrates on two strengths: a 15 percent gel and a 20 percent cream. For rosacea the 15 percent gel performed comparably to metronidazole, and for acne the reductions in lesions were comparable to topical retinoids with better tolerability in some studies.

The pregnancy part

This is the reason the page exists in this cluster. MotherToBaby records that “ACOG suggests that OTC topical products containing benzoyl peroxide, azelaic acid, salicylic acid, or glycolic acid may be used during pregnancy, if needed.”

Four ingredients named by a clinical body, and azelaic acid is one of them. That is a much stronger statement than the absence of a warning, which is what most reassurance on the internet actually amounts to.

The absorption numbers support it. A review of the mechanism reports that a 15 percent gel “does not increase plasma AzA concentration beyond the level derived from nutrition and endogenous metabolism”. You already have azelaic acid in your blood from eating grain and from ordinary fatty acid metabolism, and a topical gel does not add measurably to it.

What to expect from it

Mild transient stinging, scaling or redness in the first weeks is the common experience and it usually settles. The review describes it as well tolerated and notes that it does not cause allergic sensitisation or photosensitivity, which distinguishes it from Glycolic acid and from the retinoids.

It is slow. Pigmentation responses in particular are measured in months rather than weeks, and a product abandoned at four weeks was abandoned before the evidence says anything happens.

The label problem

The same one that runs through all of cosmetics: concentration is what matters here and the ingredient list does not carry it.

The studied strengths are 15 and 20 percent. Below the 1 percent mark on an ingredient list the order carries no information at all, which is set out in the guide to reading a cosmetics label. A serum listing azelaic acid twelfth has told you almost nothing, and a product that states a percentage on the front has told you more than the entire back of the pack.