Disodium Phosphate
Mineral pH buffer. Together with sodium dihydrogen phosphate it keeps formula pH near the physiological 5.5-6.5. No sensorial impact and no skincare effect. Pregnancy-safe.
Supporting ingredient
It gives a product its texture, stability or shelf life. It has no claimed effect on the skin, so an efficacy tier does not apply. What is known about its safety is below
Tolerability and safety
- Irritation potential
- Low
- Allergen risk
- Low
- Pregnancy
- Safe
- Suitable for
- Normal, Dry, Combination, Oily, Sensitive
About this ingredient
Disodium Phosphate (Na2HPO4) is an inorganic sodium salt of orthophosphoric acid. In pharmaceutical and cosmetic formulas it works as a pH buffer: paired with sodium dihydrogen phosphate (NaH2PO4) it forms a phosphate buffer system stable in the pH range 6.0-7.5. INCI: Disodium Phosphate. Food code E339(ii). In cosmetics it is used at 0.05-0.5% to keep the formula at its target pH. Particularly important in toners, essences, vitamin C serums (low pH 3.5 required), AHA/BHA exfoliants (pH 3.5-4.5), and niacinamide creams (pH 5.5-7). Without a buffer, pH drifts over time and actives lose efficacy or start to irritate. Pregnancy safety. Topical use is safe. Systemic absorption through the skin is minimal. Disodium phosphate is also used in injectable pharmacology – the human safety profile is established. Skin tolerance. Low irritation and allergen potential at cosmetic concentrations. At very high levels (>5%) it can slightly irritate mucous membranes – these levels are not used in cosmetics. No standalone active effects. This is a background ingredient that keeps other ingredients working. Marketing rarely calls it out, but without a buffer most active formulas do not perform as claimed.
Frequently asked questions
Is Disodium Phosphate safe during pregnancy?
Disodium Phosphate is considered safe during pregnancy at typical cosmetic concentrations. Systemic absorption through the skin is minimal.
What skin types is Disodium Phosphate for?
Disodium Phosphate suits: normal, dry, combination, oily, sensitive.
What is Disodium Phosphate and what does it do in cosmetics?
Mineral pH buffer.
Is Disodium Phosphate comedogenic?
On the Fulton scale 0/5 – non-comedogenic. For acne-prone skin, a rating of 3 or higher suggests choosing an alternative.
What's the INCI name for Disodium Phosphate?
The INCI name is Disodium Phosphate. It may also appear as: Sodium Phosphate Dibasic, Na2HPO4.
See Disodium Phosphate in a product composition right on the store page
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Similar role in the formula
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