Azelaic acid: An anti-inflammatory and depigmenting agent for acne, rosacea and dark spots

What it is

Azelaic acid is a dicarboxylic acid found naturally in cereals such as wheat and barley. It has three actions: it holds back the acne bacterium (Cutibacterium acnes), reduces melanin production and is anti-inflammatory. It is useful in acne, papulopustular rosacea and melasma and post-inflammatory dark marks, including on darker skin.

At 15–20% it is a medicine (cream or gel); in cosmetics it appears at lower concentrations or as derivatives. It does not cause photosensitivity and combines well with vitamin C or a retinoid, introducing them one at a time.

Mechanism of action

It works through:

A bacteriostatic effect against Cutibacterium acnes (it reduces colonisation)
Inhibition of tyrosinase and melanogenesis (it fades dark spots)
An anti-inflammatory effect: it reduces pro-inflammatory cytokines in the follicles

At the counter

When to recommend it

Mild to moderate acne (as an add-on to retinoids)
Inflammatory rosacea
Melasma (dark patches on the face)
Post-inflammatory hyperpigmentation

When not to

Known allergy to azelaic acid
Severe dermatitis / active atopic dermatitis
Open wounds (avoid until healed)

What to say at the counter. What to warn about: in the first few days a mild itch or sting is normal, and it usually settles within 2–3 weeks. Apply it to clean, dry skin, and use sunscreen in the morning, especially if there are dark spots.

Warnings

Caution Irritation and itching: very common at first, usually temporary.
Caution Depigmentation: on very dark skin it can cause lightening if overused.
Caution Do not start it at the same time as a very strong retinoid (let the skin adapt to one first).
Caution Pregnancy and breastfeeding: absorption is minimal and it is usually considered compatible; confirm with the doctor.

Pharmacokinetics

Absorption: Minimal skin absorption (< 3–5%). It acts mainly locally. Local peak at 2–4 hours.
Distribution: Local action in the epidermis. Minimal systemic penetration.
Metabolism: Local metabolism in the skin.
Elimination: Mostly shed unabsorbed (with skin turnover). The absorbed fraction: renal.

Azelaic acid vs retinol

Aspect	Azelaic acid	Retinol
Antibacterial action	Yes	No
Depigmentation	Excellent	Moderate
Initial irritation	Moderate	High (especially strong retinoids)
Photosensitivity	No	Yes (strict sun protection needed)
Compatibility	Good (complements retinol)	Can be used together, with care

Azelaic acid for acne + dark spots. Retinol for anti-ageing + acne, but it needs a period of adaptation.

Self-assessment

Three questions. When you check your answers you will see the explanation for each one.

What is azelaic acid's main mechanism in acne? It exfoliates the whole skin It removes sebum Bacteriostatic against the acne bacterium, and anti-inflammatory
A patient with melasma asks about azelaic acid. Is it appropriate? Yes, it has a depigmenting action through tyrosinase inhibition No, it doesn't work for melasma Yes, but only on fair skin
What is an expected effect in the first 2–3 weeks? Mild irritation and itching, which usually improve as the skin adapts No effect at all Acne disappearing immediately

Training content. It does not replace the summary of product characteristics or clinical judgement.

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