What Is Citric Acid And Its Benefits for Skin

Flip over almost any skincare product and scan the ingredients list. Somewhere near the bottom, between the preservatives and the parfum, you will usually spot citric acid. It has a reputation problem: because it sounds like the sour stuff in a bag of sweets, plenty of people assume it is either a harsh stripping agent or a filler ingredient with no real job. Neither is true.

Citric acid is one of the most versatile ingredients in modern formulation — a genuine alpha-hydroxy acid (AHA) when used at meaningful levels, and a quiet piece of background engineering when used at low ones. Understanding which role it is playing in a given product is the difference between expecting exfoliation and expecting nothing at all.

Here is what citric acid actually is, what it does for skin, and exactly where you will find it across the REFORM Skincare range.

What is citric acid?

Citric acid is a weak organic acid that occurs naturally in citrus fruits — lemons, limes, oranges and grapefruits — which is where it gets its name. It was first isolated from lemon juice in 1784 by the Swedish chemist Carl Wilhelm Scheele, and today it is produced commercially by fermenting glucose with the mould Aspergillus niger. The version used in cosmetics is chemically identical to the version in a lemon; the source just happens to be a fermentation tank rather than a fruit.

Structurally, citric acid belongs to the family of alpha-hydroxy acids. An AHA is an organic acid with a hydroxyl group attached to the carbon adjacent to the carboxylic acid group — that specific arrangement is what allows the molecule to interact with the bonds holding dead skin cells together. The better-known AHAs are glycolic and lactic acid, and the FDA lists both along with citric acid among the acids commonly used in cosmetic products. Citric acid has one feature the others do not: three carboxylic acid groups rather than one, which is why it can also act as a chelating agent, grabbing onto metal ions that would otherwise destabilise a formula.

On an ingredients list you will usually see it simply as Citric Acid, or occasionally under its chemical name, 2-hydroxy-1,2,3-propanetricarboxylic acid. In the EU and UK, where INCI naming applies, it appears under the same plain name. It is also used as a flavouring and preservative in food, which is a reasonable shorthand for how safe the molecule is — the Cosmetic Ingredient Review Expert Panel assessed citric acid and concluded it is safe in the present practices of use and concentration in cosmetics.

The two roles it plays in a formula

This is the part most articles skip, and it is the most useful thing to understand.

At low levels, citric acid works as a pH adjuster and buffering agent. Almost every skincare formula needs to sit within a specific pH window — the skin's own acid mantle sits around pH 4.5 to 5.5, and many actives only function within a narrow range. Citric acid is a convenient tool for nudging a finished formula into that window and holding it there. At these levels it is not exfoliating anything. It is doing the same job as a thermostat: keeping the conditions right so the ingredients that are active can do their work. It also serves as a chelating agent, binding trace metals from water and raw materials that would otherwise cause a formula to discolour, oxidise or lose potency over time.

At higher levels, citric acid functions as a true AHA exfoliant. It loosens the bonds between dead surface cells so they shed more easily, revealing fresher skin underneath. How much exfoliation you get depends on three things: the concentration of the acid, the pH of the final product, and what else is in the formula. The FDA's own guidance for AHA-containing cosmetics points to a concentration of 10 per cent or less and a final pH of 3.5 or greater as the parameters within which products can be formulated with adequate safety data.

So the same ingredient name on a label can mean "this is an exfoliant" or "this is housekeeping". Both are legitimate. The role depends entirely on where in the list it appears and how much of it is there.

What are the benefits of citric acid for skin?

Gentle surface exfoliation

As an AHA, citric acid helps dissolve the desmosomes — the protein "rivets" that hold dead keratinocytes onto the skin's surface. When those bonds loosen, dull, flaky cells slough away and the skin beneath reflects light more evenly. Citric acid is generally considered one of the milder AHAs, partly because its molecule is larger than glycolic acid's and therefore penetrates less aggressively, which makes it a reasonable option for people who find glycolic acid too much.

Brighter, more even tone

The immediate visible payoff of exfoliation is radiance. A build-up of dead cells on the surface scatters light and makes skin look grey and tired, and it also exaggerates the appearance of uneven pigmentation. Regular, gentle resurfacing keeps that layer turning over, which is why citric acid shows up in brightening treatments. There is also clinical literature suggesting citric acid is useful in the management of melasma and pigmentation concerns.

Support for cell renewal and skin thickness

This is where citric acid has more evidence behind it than its reputation suggests. A study published in Dermatologic Surgery examined a 20 per cent citric acid lotion applied over three months and found increases in viable epidermal thickness and dermal glycosaminoglycan content in the treated skin — changes comparable to those seen with glycolic acid and retinoic acid. Thicker, better-hydrated skin translates into a more resilient barrier and a smoother appearance over time.

Antioxidant and chelating activity

Citric acid has antioxidant capacity in its own right, and because it binds metal ions it also protects other antioxidants in a formula from being degraded by trace metals. That is one reason it is often found alongside vitamin C, vitamin E and phytic acid — it is not just compatible with them, it helps them last.

Better-behaving formulas

Though it is a behind-the-scenes benefit rather than a visible one, citric acid's pH-adjusting and chelating work keeps active ingredients stable and effective. A formula whose pH drifts is a formula whose actives stop working. That matters for you even if you never notice it on the label.

Realistic expectations

The FDA's adverse-event review of AHA products recorded reports including burning, dermatitis, swelling, pigmentary changes and increased sunburn, though it noted that the more serious reactions tend to occur with products causing the greatest degree of exfoliation, such as professional peelers. For an at-home product formulated within the usual parameters, and used sensibly, citric acid is well tolerated by most people. The two things worth knowing: AHAs can increase sun sensitivity, so daily sunscreen is non-negotiable while you are using them; and if you have sensitive or compromised skin, patch test first.

Which REFORM Skincare products contain citric acid?

REFORM Skincare uses citric acid across the range in both capacities — as a genuine exfoliating active in some products, and as a pH adjuster and stabiliser in others. Here is where you will find it in the range.

Repair & Renew Gel — where citric acid is the point

This is the one product in the range where citric acid is listed as a named active rather than a support ingredient, and it is worth understanding why. Repair & Renew Gel is described as a gentle at-home resurfacing treatment, and citric acid is formulated alongside phytic acid — a plant-derived exfoliant and antioxidant that dissolves dead skin cells and chelates the minerals that contribute to dullness. Citric acid provides mild surface exfoliation and brightness, and simultaneously balances the pH so the other exfoliating ingredients work as intended. It is a good illustration of how the two roles overlap: here, the acid is doing both jobs at once.

It is positioned for anyone looking to brighten dull skin, even out tone and decongest clogged pores, and it comes in at €40.

Intensive Moisturiser — citric acid as pH adjuster

The Intensive Moisturiser's active story is niacinamide, macadamia seed oil, carnosine with vitamin E and ascorbyl palmitate, and hydrolysed hyaluronic acid. It is an ultra-nourishing cream built for dry, sensitive and menopausal skin, formulated to restore hydration and reinforce the barrier. Citric acid appears in the formula under "stability and preservation", described explicitly as a pH adjuster that balances the formula. There is no exfoliation happening here, and there is not meant to be — this is a cream for skin that needs building up, not resurfacing. €52.

Skin Barrier Repair Cream — pH adjuster alongside lactic acid

The Skin Barrier Repair Cream is a rich emollient for very dry, rough, flaky and compromised skin, built around urea, 3.6% lactic acid, vitamin E, olus oil and pro-vitamin B5. Lactic acid is the AHA doing the exfoliating work here, at a concentration and in a base suited to dry and sensitive skin; it also stimulates ceramide production. Citric acid sits in the "stability and preservation" section of the list as a pH adjuster maintaining skin-friendly pH, next to sodium hydroxide and sodium phytate. €56.

Salicylic Acid Foaming Cleanser — pH adjuster and stabiliser

Part of the Anti-Blemish Kit, this cleanser leads with 2% salicylic acid to penetrate pores, dissolve excess sebum and help prevent new blemishes forming without stripping moisture. Citric acid appears at the very end of the ingredient list, functioning as a formula stabiliser. In a cleanser it is worth remembering that contact time is short, so ingredients at this position are doing structural work rather than acting on the skin.

The Anti-Blemish Kit serum — pH adjuster in a mandelic-led formula

The kit's exfoliating step is built around mandelic acid, phytic acid, glycolic acid, allantoin, resveratrol and bisabolol, with citric acid appearing at the close of the list as the pH adjuster for a formula whose pH needs to be tightly controlled for those acids to function.

How to use citric acid products sensibly

A few practical points if you are introducing an AHA product into your routine.

Start slowly. Twice a week is plenty for the first fortnight. Build up gradually rather than going daily from day one, and let your skin tell you how it is coping.

Sunscreen every day. This is not optional. AHAs can make skin more susceptible to sunburn, and the work you are doing to brighten and even out tone is undone by unprotected UV exposure. The range includes an SPF30 Antioxidant Cream for exactly this reason.

Do not stack exfoliants on the same night. If citric acid is exfoliating in one product, layering a retinol, a glycolic cleanser and a scrub on top of it in one sitting is how irritation happens.

Give it eight to twelve weeks. Cell turnover and the epidermal changes seen in the clinical work take months, not days. Change in skin texture is a slow-burn result.

Patch test if your skin is reactive. Apply to a small area first, and if you get prolonged stinging, irritation or redness, stop and let your skin settle.

Frequently asked questions

Is citric acid bad for your skin?
No — it is one of the better-studied cosmetic acids. The Cosmetic Ingredient Review Expert Panel concluded it is safe at current concentrations and practices, and the FDA's cautionary parameters for AHA products (10 per cent or less, pH 3.5 or above) reflect how it is normally formulated for at-home use. Problems arise from overuse and from stacking several exfoliating products, not from the ingredient itself.

Is citric acid the same as lemon juice on your skin?
No, and this is worth being clear about. Lemon juice is unpredictably acidic and contains other compounds that can irritate or cause photosensitivity. Citric acid in a formulated product is a known quantity at a controlled concentration and pH, in a base designed to buffer it. Do not substitute fruit for a formulation.

Does citric acid exfoliate in every product it appears in?
No. In the Intensive Moisturiser, Skin Barrier Repair Cream, Salicylic Acid Foaming Cleanser and the Anti-Blemish serum, it is present as a pH adjuster and stabiliser. Only in Repair & Renew Gel is it positioned as a named exfoliating active.

Can I use citric acid with vitamin C and retinol?
Citric acid is compatible with both, and its antioxidant and chelating properties are actually useful alongside vitamin C. The question is timing and load: if you are using a dedicated AHA treatment, alternate it with retinoid nights rather than stacking them, and always finish the morning with sunscreen.

Is citric acid suitable for sensitive skin?
It is generally considered among the milder AHAs because of its larger molecular size, and it is used in REFORM products specifically formulated for dry and sensitive skin — though in those products it is acting as a pH adjuster rather than an exfoliant. If you have a compromised barrier, prioritise repair first and introduce an exfoliating AHA treatment later.

What about pregnancy?
Citric acid itself is not one of the ingredients usually flagged as a concern in pregnancy. If you are pregnant or breastfeeding, check the full routine with your GP or midwife, particularly where retinoids are involved.

The short version

Citric acid is a naturally occurring weak organic acid, an AHA by structure, and one of the most useful multi-purpose ingredients in a formulation chemists' toolkit. At low levels it holds a formula at the right pH and stops trace metals from degrading the actives — quiet, essential, invisible. At meaningful levels it exfoliates, brightens, supports cell renewal and contributes antioxidant protection.

In the REFORM Skincare range, citric acid appears across five products: it is the named exfoliating active in Repair & Renew Gel, and a pH adjuster and stabiliser in the Intensive Moisturiser, Skin Barrier Repair Cream, Salicylic Acid Foaming Cleanser and the exfoliating serum in the Anti-Blemish Kit.

The ingredient is not the story. What the formula asks of it is. Read the position on the list, and you will know which version you are holding.