Ingredient

Lactic Acid

A mid-sized acid that exfoliates and holds water at once. The usual pick when glycolic acid is too much.
Dr. Schwarz, MD · Board-certified dermatologistLast reviewed September 8, 2026
Five lactic acid serums lined up on white, from The Ordinary, Glytone, Paula's Choice and Prequel

Start here

Lactic acid is what I suggest to people who want an exfoliating acid without a project. The molecule is larger than glycolic acid's, so it works more slowly and stings less, and it is a humectant, so it pulls water into the surface while it exfoliates. That combination is why it suits dry and sensitive skin, and why I recommend it for bodies more than faces — a 10% or 12% lotion most nights does more for bumpy arms and scaly shins than anything else on the shelf. It is not faster or stronger than glycolic acid; it trades a little speed for a lot more comfort.

— Dr. Schwarz, Board Certified Dermatologist

Key Facts

−
Also calledAHA, alpha hydroxy acid, ammonium lactate (a partly neutralized form used in body lotions)
TypeAlpha hydroxy acid (AHA), exfoliates and hydrates
Strengths soldRoughly 5% to 12% over the counter. Twelve percent lotions are the standard for very dry, rough or scaly skin. Higher concentrations are used for professional peels.
UseAt night. Two or three times a week on the face, most nights on the body.
Time to workDays for softness and hydration, 8 to 12 weeks for tone
Prescription neededNo at skincare strengths

What It Is

−

Lactic acid is an alpha hydroxy acid, like glycolic acid. It was first found in soured milk, but the skincare version is fermented or made in a lab, so a dairy allergy is not a reason to avoid it. Your skin already contains it. Lactic acid is part of natural moisturizing factor, the mix of molecules inside surface cells that holds water in place. That is why it is both an exfoliant and a humectant. Its molecule is larger than glycolic acid's and smaller than mandelic acid's, putting it mid-family for speed and sting. On labels it also appears as ammonium lactate, lactic acid partly neutralized with ammonium hydroxide. Less acidic, less irritating, and what most 12% body lotions for very dry, scaly skin use.

How It Works

−

Lactic acid does two things at once, and the second is why people choose it.

The first is exfoliation. Like other AHAs it loosens the protein bonds holding dead cells to the surface, so the oldest layer sheds instead of building up. Skin feels smoother, flaking settles, and the flat brown marks in those cells fade gradually.

The second is water. Lactic acid pulls water into the top layer and keeps it there, so it softens what is underneath while it removes the rough surface. That is why it rarely leaves skin tight and stripped. Laboratory work suggests it also prompts more ceramides, the fats that seal the barrier, though whether that matters in practice is unclear.

At 10% to 12% it breaks down thickened scale. That is why it is standard for very dry skin, keratosis pilaris and the scaling of ichthyosis.

Some evidence says it interferes with pigment production too. That effect is smaller and less certain than the exfoliating one.

Here is where Lactic Acid acts in the skin, and what the others do instead.

About Lactic Acid
Compare
Skin basics
LOOSENS DEAD SKINSTAYS ON THE SURFACEPULLS WATER INPULLS WATER INSEALS WATER INSEALS WATER INFILLS THE GAPSFILLS THE GAPS

These acids work at the surface. They break the bonds holding dead cells to each other, so the top layer sheds more evenly. Skin looks smoother and brighter, and anything applied afterwards gets in more easily. Exfoliates and holds water, which is why it suits dry skin.

Lactic acid is water-loving and larger than glycolic, so it moves more slowly through the outer layer. Gentler, and it holds water as well as exfoliating.

A humectant draws water into the outer layer and holds it there. Skin holding more water is plumper and more flexible, and fine lines caused by dryness soften within minutes. Seal it with something on top or in dry air the water can simply evaporate away.

A humectant draws water into the outer layer and holds it there. Skin holding more water is plumper and more flexible, and fine lines caused by dryness soften within minutes. Seal it with something on top or in dry air the water can simply evaporate away.

An occlusive sits on the surface and slows water escaping. It adds nothing to the skin; it stops what is already there from leaving, which is why it works best over damp skin.

An occlusive sits on the surface and slows water escaping. It adds nothing to the skin; it stops what is already there from leaving, which is why it works best over damp skin.

Emollients are oils and lipids that sit in the spaces between the cells of the outer layer, the mortar between the bricks. They fill those gaps rather than covering them over, so skin feels smoother straight away, water stays in and irritants stay out.

Emollients are oils and lipids that sit in the spaces between the cells of the outer layer, the mortar between the bricks. They fill those gaps rather than covering them over, so skin feels smoother straight away, water stays in and irritants stay out.

The outermost layer, and the one every moisturizer is aiming at. It is dead — flattened cells stacked like bricks, with a mix of fats as the glue between them. That glue is what holds water in and keeps irritants out.

The outer layer, and the only one anything in a jar reaches. It renews itself constantly: a cell made at the bottom takes about a month to reach the surface and flake off. Most of what a skincare product does, it does here.

The living layer underneath, holding the blood vessels, the nerves and the collagen. It is where lasting change happens and it is hard to reach: most of what is sold for the skin never gets this far.

What It Treats

−
Keratosis Pilaris

Keratosis Pilaris

Strong evidence

Ammonium lactate or lactic acid lotion at around 12 percent does the same two jobs as urea, slightly more gently, and it is often the easier one to keep using daily. Good first choice if urea stings. Like everything here, it manages the bumps rather than ending them.

Dry Skin (Xerosis)

Dry Skin (Xerosis)

Moderate evidence

Loosens stuck-together flakes chemically and draws water in at the same time, so it suits rough, bumpy dryness on the arms and legs. It is gentler than urea on large areas but stings more on cracks and on freshly shaved skin. Use it two or three times a week alongside a plain cream, not instead of one.

Forms

−

Lactic acid is a bigger molecule than glycolic acid, so it works more slowly, stings less, and holds water while it exfoliates. The base matters as much as the acid. Ammonium lactate is the same acid partly neutralized, so it is milder, and most body-use evidence rests on it. The strongest over-the-counter products are body lotions at 10% or 12%.

A row of Lactic Acid products sold as serum, photographed on white.
Face, leave-on
Serum
Usually 5% to 10% in a light base. The gentlest of the AHA serums.
A row of Lactic Acid products sold as toner, photographed on white.
Every other night
Toner
Swept on after cleansing. Low strength, easy to build up slowly.
A row of Lactic Acid products sold as body lotion, photographed on white.
Dry, bumpy arms and legs
Body lotion
10% to 12% in a moisturizing base. Where lactic acid does its best work.
A row of Lactic Acid products sold as ammonium lactate cream, photographed on white.
Very dry or scaly skin
Ammonium lactate cream
Partly neutralized, so it is milder. Made for daily use on rough skin.
A row of Lactic Acid products sold as wash-off peel, photographed on white.
A stronger evening
Wash-off peel
Higher strength left on for minutes, then rinsed. Not for broken or sore skin.

Strengths

−

Face and body sit in different parts of this ladder. A strength that is routine on shins is too much nightly on cheeks.

WeakestStrongest
Under 5%5% to 10%10% to 12%20% to 50%
Everyday
Under 5%
Cleansers, toners, light lotions. Mild.
The standard face range
5% to 10%
Most serums and treatment lotions. Enough for texture, dullness and gradual work on tone.
Body strength
10% to 12%
Where the evidence for very dry, rough, bumpy skin sits, as lactic acid or ammonium lactate lotion. Some use the lower end on the face.
Professional peel
20% to 50%
Applied in a clinic for a set time, then neutralized, usually as a course.

Basics

−
When to Apply
At night, on clean dry skin, before moisturizer. On the body, after showering, while skin is still damp.
How to Start
Two nights a week on the face for a fortnight, then build up if you are comfortable. On the body, most nights within a week or two.
If It Irritates
A mild sting for a minute is normal. If redness or tightness lingers, drop the frequency, moisturize first, or switch to a partly neutralized product. Keep it off cracked or raw skin.
If It’s Not Working
Give it eight to twelve weeks for tone. For dry or bumpy body skin, check the strength — a 5% lotion is often too light, and 10% to 12% is where the evidence sits. Wear sunscreen daily if you are working on marks.

Sample Routine

−

Here is where Lactic Acid sits in a day, and what goes around it. Pick what you are treating and what your skin is like, and the rest of the routine changes to suit.

What to Expect

−
Nights 1 to 3 | Adjusting
A brief sting, often milder than expected. Skin may feel softer straight away, which is the hydration, not the exfoliation.
Weeks 1 to 2 | Working
Flaking settles and skin feels smoother. Rough patches on the body soften noticeably.
Weeks 4 to 8 | Building
Tone looks more even and brown marks start to lighten.
After 12 weeks | Judge it here
If tone has not shifted with consistent use and daily sunscreen, change strength or ingredient.

What to Avoid

−
  • Lactic acid fits into a routine easily Most problems come from using it on damaged skin.
  • Using it on cracked or raw skin Cracked, raw or eczema-flared skin stings badly. Let the barrier heal first.
  • Stacking it with a retinoid On the same night, while you are starting. Alternate nights until both are comfortable.
  • Scrubs, brushes and exfoliating cloths Chemical plus physical exfoliation is how people end up sore.
  • Skipping sunscreen AHAs make skin burn more easily, and sun undoes work on brown marks.
  • Freshly waxed, shaved or sunburned skin Leave a few days either side.
  • Assuming stronger is better on the face The 12% that is routine on shins is more than facial skin wants several nights a week.

If You Stop

−

Dryness and rough texture come back within a few weeks. Skin that was smooth on a nightly lotion returns to baseline over about a month, bumpy arms sooner. Marks that faded stay faded. Those pigmented cells were shed, not switched off. What stops is the ongoing clearing, so new marks sit around longer. Nothing rebounds. Many people use lactic acid seasonally, more in winter and less in summer, and that is reasonable.

Ask Your Doctor

−
If you are pregnant or breastfeeding
Ask the doctor managing your pregnancy before starting or continuing.
If the skin there is broken or inflamed
With eczema, psoriasis or broken skin, acids sting sharply and can set a flare back.
If you have melasma
Uneven pigment needs a plan, and irritation can darken it.
If new dark or pale patches appear
On treated skin, especially on deeper skin tones.
If redness or burning is still there
The next day, that is more than expected.
If you are treating a child's skin
Strengths and areas need checking, not assuming.
If you already use an acne prescription
Ask how to fit an acid around it.

How It Compares

−
Four glycolic acid toner and liquid bottles lined up on white, one with its box16:9 hero for Glycolic Acid. Never cropped: the tone strip and the corner logo depend on the full frame.

Glycolic acid

The same

Smaller molecule, faster on rough texture and dullness, and more likely to sting. Lactic acid is the more comfortable option and adds hydration.

Five mandelic acid serums and their boxes lined up on white with clear gel swatches16:9 hero for Mandelic Acid. Never cropped: the tone strip and the corner logo depend on the full frame.

Mandelic acid

Different job

Gentler again and mildly antibacterial, which suits acne-prone skin. It is slower and much less studied.

Five PHA toner and serum bottles lined up on white with clear liquid swatches beside them16:9 hero for Polyhydroxy Acids (PHAs). Never cropped: the tone strip and the corner logo depend on the full frame.

Polyhydroxy acids

Worse

The mildest option, also hydrating, and they have not been shown to increase sun sensitivity. They do less.

Five white jars of 40% urea cream lined up, several also listing 2% salicylic acid16:9 hero for Urea. Never cropped: the tone strip and the corner logo depend on the full frame.

Urea

The same

Another option for very dry and scaly skin, and often combined with lactic acid in the same product. Urea softens thickened skin without being an acid.

Paula's Choice 2% BHA exfoliant, La Roche-Posay Effaclar cleanser and a CeraVe psoriasis cream pumpLabeled cutaway diagram of a single skin pore, headed Salicylic Acid. The epidermis is a brick-textured band across the top and the dermis is pink below it, with a yellow oil gland at the base of the pore and a small cluster of bacteria inside it. A single dark navy callout line points into the top of the pore: decreases dead cells in pore. There are no other callouts, so the drawing shows one effect where the other ingredient diagrams show two or three.

Salicylic acid

Different job

Works inside the pore, so it is the better choice for blackheads and acne, and a poorer choice for dryness.

Retinoids

Different job

More effect on lines and acne over time, on a slower timeline and with more irritation.

Plain emollients

Different job

For comfort, none for exfoliation. They soothe dry skin but do not clear the thickened surface that lactic acid removes.

Myths

+
  • “Lactic acid comes from milk, so I should avoid it if I am dairy intolerant.” Skincare lactic acid is made by fermenting sugars or in a lab. No milk protein, no link to lactose intolerance.
  • “It is the weak one, so it does not really do anything.” Slower than glycolic acid, not inactive. The 12% strength has a solid record for very dry, scaly skin, and comfort is what lets people use it long enough to see a result.
  • “Because it hydrates, it cannot irritate.” It is still an acid. Nightly at high strength on sensitive facial skin, it stings and reddens like any other.
  • “Lactic acid is only for dry skin.” Dry skin is where it shines, but it suits most skin types.
  • “It exfoliates, so I do not need a moisturizer.” It draws water in. A moisturizer on top keeps it there.

Questions Patients Ask

+

Is lactic acid gentler than glycolic acid?

Usually. The molecule is bigger, so it moves in more slowly, and it hydrates while it exfoliates. Gentler does not mean weaker at everything — on dry, flaky skin it often does more.

Will it help the bumps on the backs of my arms?

It is the most useful over-the-counter option for keratosis pilaris. A 10% or 12% lotion most nights softens bumps and roughness over several weeks. It manages rather than cures, so they return if you stop.

Can I use it if I am lactose intolerant or allergic to dairy?

Yes. It is made by fermentation or synthesis and contains no milk protein. The name is about where it was first found.

Is lactic acid safe in pregnancy?

Very little is absorbed, but that decision belongs with the doctor managing your pregnancy.

Can I use it every night?

On the body, most people can. On the face, two or three nights a week is the usual landing point; nightly costs more in irritation than it returns.

What is ammonium lactate, and is it different?

Lactic acid partly neutralized, so less acidic and less irritating at the same percentage. For daily use on very dry or scaly skin it is the more comfortable form, and much of the body-skin evidence used it.

References

+