AHA

AHAs (Alpha Hydroxy Acids) are water-soluble fruit acids that gently remove dead skin cells and accelerate cell renewal.

INCI name	Glycolic Acid, Lactic Acid, Mandelic Acid
category	Peeling, renewal
Suitable for	All skin types (low concentration for sensitive skin)
Typical concentration	0.5% - 30% depending on the type of acid

Characteristic	Evaluation
Anti-aging	★★★★★
Peeling effect	★★★★★
Brightening	★★★★☆
compatibility	★★★☆☆
Immediate effect	★★★★☆

Alpha hydroxy acids (AHAs) revolutionize your skincare routine with their ability to gently exfoliate the outermost layer of dead skin cells and accelerate the natural renewal process. They reduce hyperpigmentation, refine the complexion, and significantly improve the absorption of subsequent skincare products.

What is AHA?

Alpha hydroxy acids belong to the family of natural fruit acids and mainly comprise glycolic acid from sugar cane, lactic acid from fermented milk, and mandelic acid from bitter almonds. These water-soluble acids penetrate the upper layers of the skin and break down the bonds between dead skin cells, creating a natural exfoliating effect.

Unlike mechanical peels, AHAs work at the molecular level, enabling a more even and controlled exfoliation. The different types of AHAs vary in their molecular size and therefore in their penetration depth: glycolic acid has the smallest molecular size and is the most intensive, while mandelic acid has larger molecules and is therefore gentler.

In Korean skincare, AHAs are often used in low concentrations for daily application, unlike Western products that frequently rely on intensive weekly treatments. This "slow skincare" philosophy allows the skin to gradually adapt to the acids and minimizes irritation.

This is how AHA works on your skin

Accelerated cell renewal

AHAs stimulate the natural cell renewal process, which normally takes 28 days. A study by Bernstein et al. (2001) in the Journal of the American Academy of Dermatology showed that regular AHA use can accelerate cell renewal by up to 40%. This results in a fresher, more youthful complexion with improved texture.

Reduction of hyperpigmentation

By removing pigmented corneocytes in the upper layers of the skin, AHAs can effectively lighten dark spots and melasma. Lim et al. (1999) documented a 60% improvement in pigment spots after 12 weeks of treatment with 10% glycolic acid in a clinical study.

Collagen stimulation and anti-aging

AHAs promote collagen production in the dermis and reduce fine lines. A long-term study by Ditre et al. (1996) demonstrated that 25% glycolic acid treatments can increase collagen density by 25% and significantly improve skin thickness.

Improvement of product absorption

By removing the barrier layer of dead cells, AHAs improve the penetration of subsequent skincare products by up to 300%, as Green et al. (2005) were able to demonstrate in dermatological tests.

Pore-refining effect

AHAs dissolve keratinization in the pores and reduce their visible size. Kligman (2000) showed that even 5% glycolic acid leads to a significant refinement of the pores after 8 weeks.

Who is AHA suitable for?

skin type	fitness	Recommended acid	concentration
Normal	Very good	Glycolic acid	5-10%
Greasy/Impure	Excellent	Glycolic acid	8-15%
Dry	Good	Lactic acid	5-8%
Sensitive	Conditional	Mandelic acid	2-5%
Mature skin	Excellent	combination	10-20%

Integration into your K-Beauty routine

Application time: AHAs should only be used in the evening, as they increase the skin's sensitivity to light. Start with 2-3 applications per week and gradually increase the frequency until your skin has adjusted.

Routine Position: Apply AHA products after cleansing and before essences or serums. For low-concentration AHA toners, you can use them directly after cleanser. Wait 10-15 minutes before the next skincare step for optimal results.

Combination guidelines: Avoid using this product on the same evening as vitamin C , retinol , or BHA . This combination can cause irritation. Sunscreen is absolutely essential the following day, as AHAs can increase UV sensitivity by up to 50%.

The best K-Beauty products with AHA

For beginners: The Medicube Zero Foam Cleanser – 120 g (€16.50) offers a gentle introduction to the AHA world with mild fruit acids that work during cleansing.

Intensive treatment: The Isntree Hyper Acid4 30 Serum - 20 ml (€3.99) combines four different acids for maximum effectiveness and is ideal for experienced users.

Body care: The SOME BY MI AHA-BHA-PHA 30 Days Miracle Acne Clear Body Cleanser - 400 ml (€25.48) treats body acne and keratosis pilaris with a sophisticated acid combination.

Soothing care: The MEDI-PEEL Phyto Cica-Nol B5 Aha Bha Vitamin Calming Toner - 150 ml (€25.20) combines AHAs with soothing Cica extracts for sensitive skin.

Special treatment: The FRUDIA Peach Vinegar Shiny Foot Peeling Socks - 40 g (€4.99) use highly concentrated AHAs for intensive callus removal on the feet.

Comparison with other acids

Characteristic	AHA	BHA	PHA	Retinol
solubility	Water soluble	Fat-soluble	Water soluble	Fat-soluble
Area of ​​influence	surface	pores	surface	Cell level
Anti-aging	Strong	Medium	Soft	Very strong
compatibility	Medium	Good	Very good	Low

Myths and facts about AHA

Myth: "AHA makes the skin thinner and more sensitive in the long run."
Fact: AHAs remove only dead skin cells and simultaneously stimulate collagen production, making the skin thicker and more resilient in the long term. Initial sensitivity is temporary and subsides after an adjustment period.

Myth: "You should only use AHA in winter."
Fact: AHAs can be used year-round, but consistent sun protection is essential. Increased photosensitivity lasts for about a week after the last application.

Myth: "Higher concentrations always bring better results."
Fact: Effectiveness depends not only on the concentration, but also on the pH value, the exposure time, and individual skin tolerance. Low concentrations with regular use are often more effective than aggressive treatments.

Frequently asked questions about AHA

How long does it take for AHA to take effect?
Initial improvements in skin texture are visible after just 1-2 weeks. For anti-aging effects and pigment reduction, you should plan for at least 6-12 weeks.

Can I use AHA for acne?
Yes, AHA can help with acne by unclogging pores and reducing inflammation. However, BHA is often more effective for active acne.

What should I do if I experience irritation?
Reduce the frequency of application, use a lower concentration, or pause completely until the skin has calmed down. Use soothing ingredients such as aloe vera or niacinamide.

Do I need to perform a patch test before applying AHA?
A patch test is particularly recommended for sensitive skin or high concentrations. Apply the product to a small area of ​​skin for 24-48 hours.

Can I use AHA during pregnancy?
Low-concentration AHAs (below 10%) are considered safe during pregnancy. If you are unsure, you should consult your dermatologist.

Which sunscreen is suitable for use with AHA products?
Use a broad-spectrum sunscreen with at least SPF 30 every day. Mineral sunscreens containing zinc oxide or titanium dioxide are particularly gentle.

Can I use AHA around my eyes?
The eye area is very sensitive. Only use products specifically developed for the eye area with low AHA concentrations (below 5%).

How do I store AHA products correctly?
Store AHA products in a cool, dark place and tightly sealed. High temperatures and light can reduce their effectiveness and shorten their shelf life.