Acids for pigmentation: benefits, limits and safe use

Glycolic, lactic, mandelic and azelaic acid act in different ways. The right option depends on the cause and depth of colour, your skin sensitivity and whether inflammation is still active.

Surface exfoliating acids loosen pigmented cells in the outer skin layers. Azelaic acid also affects pathways involved in pigment production and may suit marks left after acne. Deeper pigment, melasma and a changing mole do not behave like a simple surface mark.

Irritation itself can trigger or deepen post-inflammatory darkening, particularly in skin that readily develops colour after a rash or spot. Professional chemical peels use controlled formulations that should be selected for skin tone and diagnosis; a stronger peel is not automatically a better choice.

Start with one product on a small test area and use it less often than the maximum allowed by its label. Apply moisturiser if the skin feels dry, and avoid scrubs, picking and multiple exfoliants. Do not apply acids to broken, sunburnt or freshly treated skin.

Broad-spectrum sunscreen, shade and protective clothing help prevent treated marks from darkening again. Take photographs in consistent lighting to judge gradual change rather than reacting to day-to-day differences. If prescription hydroquinone or another pigment treatment is planned, have a dermatologist explain how it fits with exfoliation.

Have a new or changing pigmented lesion assessed instead of treating it with acid, especially if it is asymmetric, has an irregular border, contains varied colours, bleeds or does not heal. These features require diagnosis rather than cosmetic lightening.

Stop the product and obtain prompt advice for blistering, swelling, raw skin or severe pain. A clinician can assess persistent patches, widespread colour change or pigmentation accompanied by another unexplained symptom.

Ask what is causing the colour, whether pigment sits near the surface, which acid is compatible with your skin tone and medicines, and how irritation should be managed. If considering a peel or light-based procedure, ask what preparation and aftercare your skin requires.