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Citric Acid

Citric acid

Well toleratedpH adjusterph-adjusterbufferchelatorexfoliant

No meaningful concern for most people; irritation is possible but rare.

Also written as: 2-Hydroxypropane-1,2,3-tricarboxylic acid

What it is

Citric acid is a weak organic acid that occurs naturally in citrus fruit, but the cosmetic grade is made industrially by fermenting sugars with the mould Aspergillus niger. In most face masks it is there purely to pull the pH down into a skin-friendly range, often paired with sodium citrate as a buffer, and it is printed accordingly: of the seventy-one masks here whose list shows the point where ingredient order stops indicating quantity, every one puts citric acid below that point. Across cosmetics as a whole the Cosmetic Ingredient Review records a far wider spread - up to 4% in leave-on products and 10% in rinse-off ones - because the same acid is also used deliberately as an exfoliant. It also binds trace metals, so it quietly supports formula stability. Only at much higher concentrations, and at a low pH, does it behave as an alpha hydroxy acid (AHA) that loosens dead surface cells.

How it shows up on a label

Position in the list tells you the role: near the bottom it is a pH adjuster, higher up it is being used as an exfoliating acid.

What it does well

  • Sets and holds the pH so the rest of the formula works properly

    Preservatives, acids and many actives only perform in a defined pH window, and healthy skin sits at roughly pH 4.5-5.5. Citric acid is the most common way to reach that window, which is why it appears in a very large share of masks.

    Strong evidence

  • At AHA-level concentrations it can improve sun-damaged skin

    A controlled study of topical citric acid on photodamaged skin found increased viable epidermal thickness and more glycosaminoglycans, comparable to other alpha hydroxy acids. This applies to deliberate AHA formulas, not to the trace amounts used for pH adjustment.

    Moderate evidence

Worth knowing

  • Can sting on broken or very sensitive skin

    Any acid at low pH can produce transient stinging on compromised skin, and this rises with concentration. At the fractional percentages used for pH adjustment, stinging is uncommon; in a deliberate AHA mask it is more likely.

Where the EU stands

No specific restriction

Not restricted for cosmetic use in the EU: citric acid has no entry of its own in Annex II (prohibited), Annex III (restricted) or Annex V (preservatives), and carries no concentration limit. The one annex entry that names it is Annex V entry 59, "Citric acid (and) Silver citrate", where the 0.2% ceiling is a control on the silver it releases (0.0024% as silver) rather than on citric acid. Finished AHA products must still be safe at their in-use pH.

Regulation (EC) No 1223/2009 - no annex entry for citric acid; named only in Annex V entry 59 (Citric acid (and) Silver citrate) · source ↗

Sources (3)

Every link goes to the original: a journal, a PubMed record or an EU document.

  1. [1]
    Citric acid increases viable epidermal thickness and glycosaminoglycan content of sun-damaged skin

    Dermatologic Surgery · 1997 · doi:10.1111/j.1524-4725.1997.tb00391.x

    Topical citric acid produced measurable increases in viable epidermal thickness and dermal glycosaminoglycans in photodamaged skin, comparable with other alpha hydroxy acids.

  2. [2]
    Skin pH: from basic science to basic skin care

    Acta Dermato-Venereologica · 2013 · doi:10.2340/00015555-1531

    Skin's naturally acidic surface pH is central to barrier repair, stratum corneum integrity and antimicrobial defence, which is the reason products are deliberately pH-adjusted rather than left alkaline.

  3. [3]
    Final Report on the Safety Assessment of Citric Acid, Inorganic Citrate Salts, and Alkyl Citrate Esters as Used in Cosmetics

    Cosmetic Ingredient Review · 2012

    A Final Report dated 27 March 2012, carrying no do-not-cite stamp. On how much is actually used it says: "Citric acid is used in almost every category of cosmetic product, with 6795 reported uses at concentrations up to 4% in leave-on formulations, 10% in rinse-off formulations, and 39% in products diluted for (bath) use." Those are maxima reported to the industry survey rather than typical levels, and the report publishes no typical figure. It records citric acid's cosmetic functions as chelating agent, pH adjuster and fragrance ingredient. Checked 31 August 2026.

Masks that contain Citric Acid