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Disodium Phosphate

Well toleratedpH adjusterph-adjusterbuffering

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

Also written as: Disodium Hydrogen Phosphate · Sodium Phosphate Dibasic · Disodium hydrogenorthophosphate

What it is

Disodium phosphate is the sodium salt of phosphoric acid with two of the three acidic hydrogens replaced. On its own it makes a mildly alkaline solution; paired with the monosodium form or with an acid it makes a buffer, a pair that resists pH change as the formula ages or as other ingredients react. That is almost always why it is on a mask list - not for anything it does to skin, but to keep the rest of the formula at the pH it was designed for.

How it shows up on a label

On all nine masks here that print it, it sits below the point where ingredient order stops indicating quantity - the most consistent placement of any name in this batch, and exactly what a buffer salt should look like.

What it does well

  • Keeps a formula at the pH its other ingredients need

    Buffering is well-understood chemistry and is the ingredient's recorded function. It matters most where pH drives whether something else works or stays stable - an acid, a preservative system, or a protein.

    Strong evidence

Worth knowing

  • Structural, with no effect of its own on skin

    The safety conclusion covering it is conditioned on the formula being non-irritating, which for a pH-adjusting salt is a statement about the pH the formula ends up at rather than about the salt. Nothing on the label tells you that final pH.

Where the EU stands

No specific restriction

Not restricted under the EU Cosmetics Regulation; it appears in no annex and has no concentration limit. The phosphates named in the annexes are unrelated substances - organophosphate pesticides and tritolyl phosphate in the prohibited list.

Regulation (EC) No 1223/2009 - no annex entry · source ↗

Sources (2)

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

  1. [1]
    Quick Reference Table: CIR conclusions by ingredient

    Cosmetic Ingredient Review · 2024

    The quick reference table records for Disodium Phosphate: "The CIR Expert Panel concluded that the following 31 ingredients are safe in the present practices of use and concentration in cosmetics as described in this safety assessment, when formulated to be non-irritating." The citation given is International Journal of Toxicology 40(S1):34-85, 2021. Checked 26 September 2026.

  2. [2]
    Regulation (EC) No 1223/2009 on cosmetic products, consolidated text of 18 May 2026

    Official Journal of the European Union · 2026

    A word-boundary sweep of the full consolidated text returns no occurrence of disodium phosphate. The thirty-six occurrences of the word phosphate are unrelated entries, chiefly organophosphates in the Annex II prohibited list such as diethyl 4-nitrophenyl phosphate, tetraethyl pyrophosphate and tritolyl phosphate. Checked 26 September 2026.

Masks that contain Disodium Phosphate