Ingredient

Citric Acid

Korean label: 시트릭애씨드

A weak organic acid found naturally in citrus fruits that plays several quiet but important roles in a formula.

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Similar ingredients

others that do something alike

Vitamin C

Pure vitamin C; an antioxidant that brightens and supports collagen.

Azelaic Acid

Calms redness and fades post-acne marks; one of the few actives considered pregnancy-friendly.

AHA exfoliant (gentle)

A gentler AHA exfoliant that also hydrates; good for first-time acid users.

What it does

moderate evidence

Most often it is a pH adjuster and buffer — used in tiny amounts to fine-tune and stabilise a product's acidity — and a chelator that binds stray metal ions to keep the formula stable. At much higher concentrations and low pH it is also an alpha hydroxy acid (AHA) that exfoliates by loosening dead surface skin cells, though it is a milder, less-studied exfoliant than glycolic or lactic acid.

Benefits

Precisely adjusts and buffers a product's pH so actives work and the formula stays stable
Chelates metal ions, improving stability and helping preservatives work
At exfoliating strengths, gently sloughs dead cells for smoother, brighter skin
Naturally derived, inexpensive and widely compatible across product types

Side effects

As a helper ingredient at low levels it is essentially non-irritating
Used as a leave-on AHA exfoliant it can sting, cause irritation, and (like all AHAs) increase sun sensitivity, so sunscreen is advised
Less skin-renewing benefit than glycolic or lactic acid at comparable use