Glycolic Acid Lotion: How a Body AHA Smooths Rough, Crepey Skin

Most of the skin on your body gets far less attention than your face, and it shows. Elbows turn rough, the backs of the arms get bumpy, shins look dry and dull, and the thin skin on the upper arms and above the knees starts to crease like tissue paper. A glycolic acid lotion is one of the few body products built to work on all of those at once.

Glycolic acid is the smallest alpha hydroxy acid (AHA), which lets it slip between dead surface cells and loosen the bonds that hold them in place [1]. In a cleanser, it gets about a minute to do that before it goes down the drain. In a lotion, it stays on the skin for hours, and that difference is why almost all of the meaningful AHA research on aging skin was done with leave-on products.

What the studies on leave-on AHA lotions found

The most striking evidence comes from a forearm study in which volunteers applied a 25% AHA lotion (glycolic, lactic or citric acid) to one arm and a placebo lotion to the other for an average of six months. The treated skin was about 25% thicker, with a thicker epidermis, more collagen in the upper dermis and better-quality elastic fibers, and there was no sign of inflammation [2].

Lower-strength lotions have been tested too, and the results suggest you do not need a 25% product to see a change. In a 22-week double-blind trial in 74 women aged 40 to 70, an 8% glycolic acid cream applied twice daily beat the plain cream on the forearms for overall photodamage and for sallowness, the dull yellowish cast that sun-exposed body skin develops [3]. On the face, 76% of the glycolic group improved by at least one grade, compared with 40% of the vehicle group. The authors called the benefit modest, which is a fair expectation to carry into the store.

Concentration still matters. In a three-month study comparing 5% and 12% lactic acid, both strengths smoothed the surface, but only the 12% lotion thickened and firmed the dermis, the deeper layer that sags and creases with age [4]. Your skin can look smoother within 2 weeks of a gentle acid lotion, but deeper collagen firming took 3 months or more, far longer than most people persist.

Where a glycolic body lotion helps most

Glycolic acid lotions are most useful on skin that is thick, dry and slow to shed:

Your skin can look smoother within 2 weeks of a gentle acid lotion, but deeper collagen firming took 3 months or more, far longer than most people persist.

• Rough elbows, knees and heels. Built-up dead cells make these areas look gray and feel coarse. An AHA lotion loosens that buildup gradually rather than scraping it off.
• Bumpy arms and thighs. The small rough bumps of keratosis pilaris are plugs of keratin around hair follicles, and a leave-on exfoliant softens them over several weeks. Our guide to keratosis pilaris treatment compares the acid and urea options in more detail.
• Very dry, scaly shins. In a four-week study of people with severe dry skin, including ichthyosis, an AHA-blend cream improved dryness, roughness and flaking within two weeks, with further gains at four weeks, outperforming a standard moisturizer [5].
• Dull, sun-exposed arms and chest. This is where the photodamage trials above were run, so the evidence is strongest here.
• Crepey upper arms and legs. An AHA lotion smooths texture and adds a little thickness over months. It will not tighten loose skin on its own, and expectations should match that.

Reading the label: percentage, pH and base

A glycolic lotion’s strength depends on two numbers, and most labels only show one. Glycolic acid only exfoliates in its “free acid” form, and how much of it stays in that form depends on the pH of the formula. A 10% lotion buffered to a near-neutral pH can do less than a 5% lotion at pH 3.5 to 4. Formulation and vehicle are a large part of why AHA products perform so differently in studies [1].

For body use, most people do well with 5% to 10% glycolic acid at a pH around 3.5 to 4.5. Products above 10% are best saved for very thick, rough areas such as heels, and they sting more on freshly shaved legs or broken skin.

The base matters as much as the acid. Look for a lotion that also contains humectants such as glycerin and barrier-friendly ingredients such as ceramides or shea butter, because acid exfoliation on its own can leave dry skin feeling tight. Fragrance adds nothing and is a common source of irritation on reactive skin.

Glycolic, lactic or urea?

Glycolic acid is the most studied AHA for photoaging, but it is not the only choice. Lactic acid is a slightly larger molecule that also draws water into the skin, which makes it a better fit for very dry or sensitive skin; our guide to ammonium lactate lotion covers the prescription-strength version. Urea softens thick, scaly skin and is often the gentlest first step for cracked heels. If you have tried a lactic or urea lotion and want more visible smoothing and brightening on sun-exposed skin, glycolic acid is the logical step up.

Your skin burns more easily after 4 weeks of a glycolic lotion, so treated arms, chest and legs need sunscreen more than most people realize.

The sunscreen rule you cannot skip

Glycolic acid makes skin more sensitive to ultraviolet light. In a randomized, double-blind study, 29 volunteers applied 10% glycolic acid (pH 3.5) or a placebo to their backs six days a week for four weeks. The glycolic sites burned more easily and showed more sunburn cells after the same UV dose, although the effect faded within a week of stopping [6].

Your skin burns more easily after 4 weeks of a glycolic lotion, so treated arms, chest and legs need sunscreen more than most people realize. If you use a glycolic lotion, apply a broad-spectrum SPF 30 or higher to any treated skin that will be outdoors, or keep the lotion for areas that stay covered.

How to use a glycolic acid lotion

1. Start slowly. Apply after showering, two or three evenings a week, on dry skin.
2. Avoid freshly shaved or broken skin. Shaving and acids together are a common cause of stinging and red patches.
3. Build up. If there is no irritation after two weeks, increase to most nights.
4. Moisturize on off nights. A plain fragrance-free cream keeps the barrier comfortable.
5. Protect in the morning. Sunscreen on any treated skin that sees daylight.
6. Give it time. Smoother texture usually shows within a few weeks; tone and firmness take months.

If you want more background on the acid itself, our overview of glycolic acid benefits covers how it works on the face as well as the body.

Where retinol fits, and why it is the next step

An AHA lotion works from the surface down. It clears dead cells and nudges the dermis to thicken over many months. Retinol works the other way, signaling skin cells directly to produce new collagen. In a randomized trial on the arms of elderly volunteers, a 0.4% retinol lotion applied up to three times a week for 24 weeks significantly reduced fine wrinkling and increased collagen production compared with the vehicle [7].

Glycolic acid and retinol are best kept on separate nights, or in separate routines, because both can irritate when layered. Our guide to retinol for the body explains how to set up a body routine that alternates them.

On the face, where skin is thinner and aging shows first, the irritation that conventional retinol causes is the main reason people quit. Nanoretinol was designed around that problem. It delivers 0.2% stabilized retinol in biomimetic lipid nanoparticles that the skin recognizes as its own, so the retinol reaches skin cells without breaking down the barrier the way conventional formulations can. In North Biomedical’s study summary, Nanoretinol was 232% more effective in collagen recovery and 73% more effective in elastin recovery than conventional retinol, and clinical use over 56 days produced a 61% increase in firmness [8].

Smooth the body with an acid lotion, protect it in daylight, and let a gentle nightly retinol do the deeper rebuilding where it counts.

References

1. Kornhauser A, Coelho SG, Hearing VJ. “Applications of hydroxy acids: classification, mechanisms, and photoactivity.” Clinical, Cosmetic and Investigational Dermatology. 2010;3:135-142. doi:10.2147/CCID.S9042
2. Ditre CM, Griffin TD, Murphy GF, et al. “Effects of alpha-hydroxy acids on photoaged skin: a pilot clinical, histologic, and ultrastructural study.” Journal of the American Academy of Dermatology. 1996;34(2 Pt 1):187-195. PubMed:8642081
3. Stiller MJ, Bartolone J, Stern R, et al. “Topical 8% glycolic acid and 8% L-lactic acid creams for the treatment of photodamaged skin. A double-blind vehicle-controlled clinical trial.” Archives of Dermatology. 1996;132(6):631-636. PubMed:8651713
4. Smith WP. “Epidermal and dermal effects of topical lactic acid.” Journal of the American Academy of Dermatology. 1996;35(3 Pt 1):388-391. PubMed:8784274
5. Kempers S, Katz HI, Wildnauer R, Green B. “An evaluation of the effect of an alpha hydroxy acid-blend skin cream in the cosmetic improvement of symptoms of moderate to severe xerosis, epidermolytic hyperkeratosis, and ichthyosis.” Cutis. 1998;61(6):347-350. PubMed:9640557
6. Kaidbey K, Sutherland B, Bennett P, et al. “Topical glycolic acid enhances photodamage by ultraviolet light.” Photodermatology, Photoimmunology & Photomedicine. 2003;19(1):21-27. doi:10.1034/j.1600-0781.2003.00013.x
7. Kafi R, Kwak HS, Schumacher WE, et al. “Improvement of naturally aged skin with vitamin A (retinol).” Archives of Dermatology. 2007;143(5):606-612. doi:10.1001/archderm.143.5.606
8. North Biomedical LLC. “Nanoretinol vs. Conventional Retinol: Efficacy in Collagen and Elastin Recovery.” Clinical Study Summary, 2024. Study summary