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Ingredient guide
disodium phosphate
In short
A buffering salt that keeps a product’s pH stable over time. This helps maintain the performance of pH‑sensitive ingredients such as vitamin C or exfoliating acids.
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Best used
Anytime
What it is
Inorganic phosphate salt used as a buffering agent and pH stabiliser. Keeps product pH within a narrow range over time, which is especially important for formulas containing pH-sensitive actives like vitamin C or acids.
Also found as
Where to find it
La Roche-Posay Pure Vitamin C10 Serum
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Common questions
It acts as a pH stabiliser, ensuring the product stays within its intended acidity range to maintain texture and ingredient stability.
Yes. It is widely used and generally well tolerated because it functions mainly within the formula rather than on the skin surface.
Stable pH helps keep products consistent and supports the effectiveness of ingredients that can degrade when pH drifts.
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Personal guidance only · For clinical concerns, see a dermatologist.