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Sodium PCA

Also known as: Sodium pyrrolidone carboxylate

A humectant related to the skin's natural moisturizing factors, with a specific nitrosation qualification in its safety review.

Indigo water-ripple print with a shallow glass dish
Editorial illustration

Sodium PCA is a salt of pyrrolidone carboxylic acid used as a humectant in cosmetics. Its role is to help a formula retain moisture, not to treat every cause of dry skin. CIR's 2019 review supported reported cosmetic uses but specified that these ingredients should not be used in products where N-nitroso compounds can form.1

  • A humectant salt, not a sodium supplement.1
  • CIR reassessed PCA and sodium PCA with additional salts in 2019.1
  • The conclusion includes avoiding conditions that allow N-nitroso compound formation.1

What is Sodium PCA?

PCA chemistry is associated with the skin's natural moisturizing factors, while the cosmetic sodium salt is a manufactured ingredient. This distinction matters: something related to normal skin chemistry can still require attention to formula composition and manufacturing. Sodium PCA is not the same as PCA's calcium, magnesium or potassium salts, though they were evaluated together.1

Where it comes from

Natural sources

  • PCA is associated with natural moisturizing factors in skin.

How it's made

Cosmetic sodium PCA is manufactured and purified as a defined salt rather than extracted from skin.

What it does in products

  • Skin-conditioning humectant

Benefits

Moisture support in a finished formula

limited evidence

Sodium PCA has a documented humectant role, but hydration outcomes belong to the tested moisturizer rather than this ingredient in isolation.1

The cited CIR report is a safety assessment and function record, not comparative evidence that sodium PCA outperforms glycerin or cures eczema.

Evidence scope and limitations

Cosmetic sodium PCA and the 2019 PCA-salt safety assessment; no oral electrolyte use.

  • The safety assessment does not establish an optimal clinical percentage.
  • The conclusion is conditional on formulation chemistry.

Evidence last checked: 2026-10-01

Side effects & safety

Finished-product irritation (varies)A favorable ingredient assessment does not eliminate reactions to fragrance, preservatives or other ingredients in the same moisturizer.

Safety considerations

  • Nitrosation compatibility is a manufacturer-level formulation issue, not a reason to invent consumer rules about which separate serums can be used together.
  • Not for: Avoid a finished product that causes a reproducible reaction; ingredient attribution may need professional evaluation.
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Amounts studied & product use

These figures describe research or common product use, not a personal dose or treatment recommendation.

In skincare studies and products

The review covers reported cosmetic concentrations, not a single clinically optimal humectant percentage. More sodium PCA does not automatically mean more moisture or a better formula.

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Regulatory status

  • A U.S. cosmetic humectant, not an FDA-approved treatment for dry-skin disease.
  • INCI name on cosmetic labels: Sodium PCA.
  • 2019: safe under reported cosmetic use; do not formulate where N-nitroso compounds can form.
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Read natural moisturizing factor as a chemistry clue

The phrase helps explain why formulators use PCA salts. It should not be read as evidence of allergy-proof, universally compatible or medically reparative performance.

A useful moisturizer also has a vehicle, an emollient or occlusive profile and a preservation system. Comparing those finished products is more meaningful than ranking sodium PCA against another humectant by name alone.

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Frequently asked questions

Is sodium PCA the same as hyaluronic acid?

No. It is a different humectant chemistry; both can appear in a moisturizer without being equivalent ingredients or requiring equal percentages.1

Does the sodium name make it drying?

The salt's documented cosmetic role is humectancy. The name alone does not predict that a finished moisturizer will dry skin.1

The bottom line

Sodium PCA is a formulation humectant. Preserve the safety review's qualification and avoid converting a function into a disease-treatment promise.

References

  1. Fiume MM, Bergfeld WF, Belsito DV et al.. Safety Assessment of PCA (2-Pyrrolidone-5-Carboxylic Acid) and Its Salts as Used in Cosmetics. International Journal of Toxicology / Cosmetic Ingredient Review (2019) · safety assessment · PMID 31522652; DOI 10.1177/1091581819856568
  2. Allergens in Cosmetics. U.S. Food and Drug Administration · government guidance · Undated live resource; accessed October 1, 2026
  3. FDA Authority Over Cosmetics: How Cosmetics Are Not FDA-Approved, but Are FDA-Regulated. U.S. Food and Drug Administration (2013) · government guidance · Page updated August 3, 2013; accessed October 1, 2026

Revision history

  1. Initial AI-assisted evidence compilation with source-linked claims, formulation distinctions and explicit research limitations; not independent medical review.