AHA vs. glycolic acid: What's the difference – and which peel is right for you?

The confusion surrounding acids in skincare

Glycolic acid, AHA, lactic acid, fruit acid peel – anyone looking into chemical peels quickly encounters a confusing array of terms. The question we receive most often is: "What exactly is the difference between AHA and glycolic acid?"

The short answer: Glycolic acid IS an AHA. It's like the little sister in a larger family. But this family has other members – and depending on your skin problem, another acid might be a better fit for you.

In this guide, we clarify the terms, explain the differences, and help you find the right scrub for your skin.

What does AHA actually mean?

AHA stands for alpha hydroxy acids – a group of water-soluble acids that occur naturally in fruits, milk, and sugar cane. That's why they are also called fruit acids, although not all of them come from fruits.

The AHA family includes several members:

Glycolic acid – from sugar cane, the smallest and therefore most penetrating AHA.

Lactic acid – from fermented milk, larger and gentler than glycolic acid

Mandelic acid – from bitter almonds, even larger and particularly gentle

Malic acid – from apples

Tartartric acid – from grapes

Citric acid – from citrus fruits

All AHAs work on the same principle: they dissolve the "glue" between dead skin cells, thus accelerating natural skin renewal. The result: smoother texture, a more even complexion, fewer age spots, and finer pores.

Glycolic acid: The powerhouse AHA

Glycolic acid is the best-known and most thoroughly researched AHA. Its advantage: It has the smallest molecular size of all fruit acids and therefore penetrates the skin most deeply.

Molecular size: 76 Daltons (for comparison: lactic acid has 90 Daltons)

Origin: Sugar cane

Strength: The most effective AHA for hyperpigmentation and wrinkles

However: It can irritate sensitive skin.

Glycolic acid is particularly suitable for normal to oily skin that needs intensive renewal. It is the first choice for enlarged pores, acne scars, and stubborn pigmentation spots.

Our Glycolic Exfoliating Liquid contains 5% glycolic acid – an effective concentration suitable even for beginners. The formula is enhanced with cranberry and lingonberry antioxidants, which protect the skin during renewal.

Lactic acid: The gentle AHA

Lactic acid is the second most popular AHA – and the gentler alternative to glycolic acid. Its larger molecules penetrate less deeply, making it more tolerable, but no less effective.

Molecule size: 90 Daltons

Origin: Fermented milk (vegan, also synthetically produced)

Strength: Exfoliates AND moisturizes simultaneously

Advantage: Better tolerated by sensitive skin

A special bonus: Lactic acid is part of the skin's natural moisturizing factor (NMF). It not only exfoliates but also improves moisture retention. That's why skin never feels dry after lactic acid peels.

Our AHA Peeling Concentrate uses 10% lactic acid – a high concentration for intensive renewal. The combination with 1% hyaluronic acid further enhances the moisturizing effect.

Direct comparison: glycolic acid vs. lactic acid

Which scrub is right for you?

Choose glycolic acid if you:

• You want to refine large, clogged pores
• You have acne scars or PIH (Post-Inflammatory Hyperpigmentation).
• If you want to lighten stubborn pigment spots
• You have normal to oily skin
• You want a quick result

→ The Glycolic Exfoliating Liquid with 5% glycolic acid

Choose lactic acid if you:

• Do you have sensitive or dry skin?
• Treat the first signs of skin aging
• You want to smooth out fine lines and wrinkles
• Wishing you a radiant glow
• Are you new to chemical peels?

→ The AHA Peeling Concentrate with 10% lactic acid + 1% hyaluronic acid

How to use AHA peels correctly

The golden rules

Apply in the evening. AHAs make the skin more sensitive to light. Always use them in the evening.

Start slowly. Begin with 1-2 times per week and increase to 2-3 times if your skin tolerates it.

SPF is essential. Use at least SPF 30 the day after exfoliation (and generally every day).

Do not combine. Do not use AHAs at the same time as retinol or vitamin C. Alternate the evenings.

Listen to your skin. A burning sensation is normal, but pain is not. Reduce application if irritation persists.

Application: The Glycolic Exfoliating Liquid

Apply to face, neck, and décolleté in the evening after cleansing using a cotton pad. Avoid the eye area. Do not rinse. Follow with moisturizer. Use 2-3 times a week.

Application: The AHA Peeling Concentrate

Apply to cleansed skin in the evening. Leave on overnight. Finish with moisturizer. Use 1-2 times a week.

AHA vs. BHA: What is the difference?

While we're on the subject of acids – another common question: What is the difference between AHA and BHA?

AHAs (Alpha Hydroxy Acids): Water-soluble. They work on the skin's surface. Ideal for age spots, wrinkles, rough texture, and a dull complexion.

BHA (Beta-Hydroxy Acid/Salicylic Acid): Oil-soluble. Penetrates pores. Ideal for acne, blackheads, and oily skin.

In short: AHAs work ON the skin, BHAs INSIDE the pores. For acne with clogged pores, BHA is often the better choice. For skin aging and age spots, AHAs are more effective.

Frequently asked questions about AHAs and glycolic acid

Can I combine glycolic acid and lactic acid?

Yes, but not on the same evening. You can alternate – for example, glycolic acid on Mondays and Thursdays, lactic acid on Saturdays. Or: glycolic acid for the T-zone, lactic acid for the more sensitive cheeks.

At what age should I start using AHA?

AHAs aren't a matter of age, but rather a matter of skin type. Even young skin can benefit from peels – for example, in cases of acne or uneven texture. For skin aging, AHAs are often recommended from the mid-twenties onwards.

How long will it take before I see results?

Initial improvements in texture and glow are often noticeable after just 1-2 weeks. For visible changes in pigmentation spots and wrinkles, expect 6-12 weeks of regular use.

Can I use AHA during pregnancy?

Glycolic acid and lactic acid are considered safe during pregnancy because they are not absorbed systemically. Nevertheless, we recommend speaking with your doctor beforehand.

Why does my skin burn after application?

A slight tingling or brief burning sensation (30-60 seconds) is normal – the acid is working. Persistent redness or pain indicates hypersensitivity. In this case, reduce the application or switch to a gentler acid.

Our conclusion

The "difference" between AHA and glycolic acid is actually nonexistent – ​​glycolic acid is an AHA, more precisely the smallest and most potent of the family. The real question is: Which AHA is right for YOUR skin?

For intensive renewal and pore care: Glycolic acid → The Glycolic Exfoliating Liquid | 5% Glycolic Acid | €59.90

For gentle renewal and anti-aging: Lactic acid → The AHA Peeling Concentrate | 10% Lactic Acid + 1% Hyaluronic Acid | €49.90

Both products are COSMOS Natural certified, vegan and free from silicones, parabens and mineral oil.

Scientific sources

1. Tang, S.C., & Yang, J.H. (2018). Dual Effects of Alpha-Hydroxy Acids on the Skin. Molecules , 23(4), 863.
2. Kornhauser, A., et al. (2010). Applications of hydroxy acids: classification, mechanisms, and photoactivity. Clinical, Cosmetic and Investigational Dermatology , 3, 135-142.
3. Sharad, J. (2013). Glycolic acid peel therapy – a current review. Clinical, Cosmetic and Investigational Dermatology , 6, 281-288.
4. Smith, W. P. (1996). Epidermal and dermal effects of topical lactic acid. Journal of the American Academy of Dermatology , 35(3), 388-391.
5. Babilas, P., et al. (2012). Chemical peels. Journal of the German Dermatological Society , 10(3), 167-176.