Thicker epidermis after 3 months at 20%
Clinical trialThe thickness of the living epidermis and the glycosaminoglycan content of the dermis increase. The authors describe changes comparable to those seen with glycolic acid and ammonium lactate4.
Citric acid in cosmetics
Citric acid is an organic acid used in cosmetics mostly as a pH adjuster and chelating agent1. At high doses it is also an alpha-hydroxy acid (AHA): two older trials tested it at 20 and 25% as an exfoliant45. The CIR panel judges it safe in current uses and concentrations3.
Citric acid at a glance
Entry from our cosmetic ingredient glossary. Regulatory data from the European Commission's CosIng database1 and Regulation (EC) 1223/20092, safety according to the CIR expert panel3. Copy the identifiers in one click for your files.
- INCI name
- CITRIC ACID
- Other names
- 2-Hydroxypropane-1,2,3-tricarboxylic acidChemical name according to CosIng1; E330 when used as a food additive
- CAS number
- 77-92-9CosIng also lists 5949-29-1, that of the monohydrate form1
- EC number
- 201-069-1
- Formula
- C₆H₈O₇Molar mass 192.12 g/mol (anhydrous form)
- CosIng functions
- Buffering, chelating, fragrance"Buffering", "chelating" and "fragrance"; CosIng does not declare an exfoliating function for it1
- Appearance
- White crystalline powderVery soluble in water, dissolves in the water phase
- EU status
- No restriction for citric acid aloneAbsent from the annexes as such. Only the mixture of citric acid and silver citrate appears in Annex V, entry 59 (preservative, 0.2%, prohibited in oral products and eye products)2
- Allergen to declare
- NoAbsent from the fragrance allergen list of Regulation (EU) 2023/1545
- Safety
- Judged safe in cosmeticsCIR panel 2014: safe in current uses and concentrations3
What the research says
Each result shows the protocol and the level of evidence. The higher the level, the better the result carries over to a finished formula.
Clinical trialReview or consensusLaboratory
Facial and body skinSkincare
Thicker skin with a 25% AHA
Clinical trialSkin thickness increases by about 25%, with a thicker epidermis and a dermis denser in collagen. The study does not separate the effect of each acid5.
More collagen, pigment more visible than with glycolic acid
Clinical trialCollagen I and procollagen I increase with glycolic, lactic and citric acids, not with acetic acid. Melanin stays more visible with citric and acetic acids than with glycolic and lactic acids, which the authors judge the most useful6.
pH, the main role in formulationFormulation
The natural pH of skin is about 4.7
Clinical trialSurface pH goes from 5.12 to 4.93 after 24 h without product; the authors estimate the natural pH at 4.7. Skin below pH 5 shows better barrier, hydration and desquamation parameters. This benchmark explains why formulas are acidified; the study does not cover citric acid10.
Mild detergents aim for a pH close to 5.5
ReviewUnlike alkaline soap, synthetic detergents with a pH close to 5.5 do not interfere with the skin flora, which is tied to surface pH11.
Expert and authority viewsDermatology
A pH adjuster and chelating agent judged safe
Expert assessmentThe panel describes citric acid as a pH adjuster, chelating agent or fragrance, and concludes that these ingredients are safe in current uses and concentrations. Because citric acid is a food additive recognized as safe in the United States, the assessment focused on skin exposure3.
AHA ceilings: 10% and pH 3.5, for glycolic and lactic acids
Expert consensusProducts with glycolic and lactic acids are judged safe up to 10%, at a pH of 3.5 or higher and with a formula or instructions that protect from the sun. These ceilings target those two acids: the FDA lists citric acid among the other AHAs without giving it a figure9.
Sun sensitivity, reversible
ReviewIn volunteers, applying AHAs increases sensitivity to UV-induced redness by 18% after 4 weeks, reversibly9. The Kornhauser review stresses the safety of prolonged use on exposed skin and notes that the mechanisms of action remain to be clarified7.
European benchmarks for neighboring AHAs
ReviewAccording to this review, the European scientific committee recommends up to 4% and a pH of 3.8 or higher for glycolic acid, 2.5% and a pH of 5 or higher for lactic acid. The optimal concentration remains poorly defined8.
This page summarizes published literature on a cosmetic ingredient. It does not describe the effect of a finished product, which depends on its formula, and it is not medical advice. Some of the studies cited were run or funded by manufacturers; this is stated in the sources. Citric acid is studied almost only as an exfoliating AHA, a minority use: its main role, adjusting pH, is the subject of no trial that isolates it.
Which products can use citric acid?
No formula in our white label catalog features citric acid yet. Our formulation lab can add it to a custom formula or to a catalog formula. Its common uses:
Face
pH adjuster in serums, toners, cleansers and creams, chelating agent for trace metals.
Body
pH adjustment of shower gels, body lotions and creams.
Hair
pH adjustment of shampoos and conditioners.
Citric, glycolic, lactic or mandelic acid?
Four alpha-hydroxy acids. Citric acid is mainly a pH adjuster; the other three are chosen as exfoliants. Each has its own detailed page.
| Citric acid | Glycolic acid | Lactic acid | Mandelic acid | |
|---|---|---|---|---|
| Main role | pH adjuster and chelating agent1 | AHA exfoliant, also a buffer in CosIng | Exfoliant and humectant | AHA exfoliant with a benzene ring |
| What the studies show | Thicker epidermis at 20%4; pigment more visible than with glycolic acid6 | Less pigment visible than with citric acid6 | Less pigment visible than with citric acid6 | See the mandelic acid page |
| EU regulation | No restriction for the acid alone12 | No restriction in the annexes. Benchmark: 4%, pH 3.8 or higher8 | No restriction in the annexes. Benchmark: 2.5%, pH 5 or higher8 | No restriction, no numeric benchmark |
| Expert opinion | CIR panel: safe in current uses3 | CIR panel: 10% maximum, pH 3.5 or higher9 | CIR panel: 10% maximum, pH 3.5 or higher9 | No dedicated opinion, see the page |
| Sun | Precaution of the AHA family at exfoliating doses9 | Increased UV sensitivity during use9 | Sun protection recommended with AHAs9 | Sun protection recommended with AHAs9 |
Frequently asked questions about citric acid
What is citric acid used for in cosmetics?
Is citric acid an AHA?
Yes, it is an alpha-hydroxy acid, listed among the AHAs by the FDA9. But it is not the most used: in the histological study cited, glycolic and lactic acids leave less melanin visible than citric acid6. See the pages on glycolic acid, lactic acid and mandelic acid.
What percentage of citric acid should a product contain?
As a pH adjuster, there is no fixed percentage: you aim for a pH and measure it on the finished formula. As an exfoliant, two older trials test 20 and 25%45, well above the benchmarks for other AHAs (4% at pH 3.8 for glycolic acid according to the European committee, 10% at pH 3.5 according to the CIR)89. The European regulation sets no ceiling for citric acid alone2.
Can you use food-grade or household citric acid in a cosmetic?
The molecule is the same, but a cosmetic requires a cosmetic-grade, traceable raw material and a pH checked on the finished formula. We advise against homemade preparations based on acid powder: pH cannot be judged by eye. For a brand, development and stability testing are part of formulation.
Is citric acid harmful to skin?
Citric acid and hair: is it useful in a shampoo?
It is used there to adjust the pH of shampoos and conditioners. We found no controlled study showing a benefit specific to citric acid on hair: this page therefore promises none.
Can you formulate a pH-adjusted product for my brand?
Yes. Our ISO 22716 certified lab sets the pH of each formula and validates it with stability tests. You start from a catalog formula to customize or from a custom formula. Free samples are included.
- Peri-procedural skincare: create a white label dermocosmetic rangeAn example of a physiological pH formula, 5.5, for sensitized skin
- Cosmetic product specification: 5 secrets to succeedOrganic specifications: the restrictive list of synthetic chemistry, pH included
- Natural vs synthetic cosmeticsOrigin of ingredients, pros and cons of each approach
- Top 10 trending cosmetic ingredients in 2026The actives to add to a white label range
Sources
Peer-reviewed studies and official regulatory sources, checked on November 3, 2026.
- European Commission. CosIng, entry CITRIC ACID (CAS 77-92-9, EC 201-069-1). ec.europa.eu/growth/tools-databases/cosing
- European Parliament and Council. Regulation (EC) No 1223/2009 on cosmetic products, version consolidated on May 1, 2025: Annex V, entry 59 (citric acid and silver citrate); no entry for citric acid alone in Annexes II to VI. eur-lex.europa.eu
- Fiume MM, Heldreth BA, Bergfeld WF, et al. Safety Assessment of Citric Acid, Inorganic Citrate Salts, and Alkyl Citrate Esters as Used in Cosmetics. Int J Toxicol. 2014;33(2 Suppl):16S-46S. doi:10.1177/1091581814526891
- Bernstein EF, Underhill CB, Lakkakorpi J, et al. Citric acid increases viable epidermal thickness and glycosaminoglycan content of sun-damaged skin. Dermatol Surg. 1997;23(8):689-694. doi:10.1111/j.1524-4725.1997.tb00391.x
- Ditre CM, Griffin TD, Murphy GF, et al. Effects of alpha-hydroxy acids on photoaged skin: a pilot clinical, histologic, and ultrastructural study. J Am Acad Dermatol. 1996;34(2 Pt 1):187-195. doi:10.1016/s0190-9622(96)80110-1
- Yamamoto Y, Uede K, Yonei N, et al. Effects of alpha-hydroxy acids on the human skin of Japanese subjects: the rationale for chemical peeling. J Dermatol. 2006;33(1):16-22. doi:10.1111/j.1346-8138.2006.00003.x
- Kornhauser A, Coelho SG, Hearing VJ. Applications of hydroxy acids: classification, mechanisms, and photoactivity. Clin Cosmet Investig Dermatol. 2010;3:135-142. doi:10.2147/CCID.S9042
- Almeman AA. Evaluating the efficacy and safety of alpha-hydroxy acids in dermatological practice: a comprehensive clinical and legal review. Clin Cosmet Investig Dermatol. 2024;17:1661-1685. doi:10.2147/CCID.S453243
- Food and Drug Administration (United States). Alpha hydroxy acids, "Cosmetic Ingredients" page. fda.gov
- Lambers H, Piessens S, Bloem A, et al. Natural skin surface pH is on average below 5, which is beneficial for its resident flora. Int J Cosmet Sci. 2006;28(5):359-370. doi:10.1111/j.1467-2494.2006.00344.xSara Lee Household and Body Care
- Schmid MH, Korting HC. The concept of the acid mantle of the skin: its relevance for the choice of skin cleansers. Dermatology. 1995;191(4):276-280. doi:10.1159/000246568
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