Acids in K-Beauty: AHAs, BHAs, and PHAs Explained

Author: Veruska Anconitano, Korean Beauty Lover And Korean Beauty JournalistAuthor information
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Veruska Anconitano
Veruska Anconitano is a Korean beauty expert, combining her expertise as a seasoned journalist with a deeply personal passion for K-beauty.
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Have you ever wondered what makes Korean skincare so uniquely effective? The answer often lies in one word: acids. But if you’re like many, navigating the complex world of skincare acids can be daunting. After all, with terms like AHAs, BHAs, and PHAs floating around, it’s easy to feel lost in a sea of acronyms and scientific jargon.

That’s where this guide comes in. I’ve spent countless hours demystifying these powerful ingredients for my knowledge, transforming what was once a complicated topic into an easy-to-understand and accessible resource. Whether you’re a Korean beauty novice or a seasoned enthusiast looking to deepen your knowledge, this guide is tailored for you.

Acids in Korean beauty aren’t just a trend but a cornerstone of some of the most influential and innovative skincare routines worldwide. From gentle exfoliation to deep hydration, these acids do more than improve the surface of your skin—they unlock its potential.

So, keep reading this guide if you want to know everything about acids in K-Beauty. Get ready to unravel the mysteries of AHAs, BHAs, and PHAs, and discover how to seamlessly integrate them into your skincare regimen for maximum safety and effectiveness.

What are Acids in Skincare?

Acids in Kbeauty

Understanding the science behind skincare acids begins with the skin’s pH and acid mantle. The skin’s surface is naturally acidic, typically ranging from a pH of 4.5 to 6.5.

This acidic environment, the acid mantle, is crucial for skin health. It is a barrier, protecting the skin from environmental aggressors, pollutants, and harmful microorganisms. When applied, skincare acids interact with this mantle, influencing its pH and, consequently, the skin’s overall health.

Skincare acids are categorized based on their molecular size, solubility, and how they interact with the skin.

Alpha Hydroxy Acids (AHAs) are water-soluble and work on the skin’s surface, primarily aiding in exfoliation and hydration. On the other hand, Beta Hydroxy Acids (BHAs) are oil-soluble, allowing them to penetrate deeper into the pores to combat issues like acne and oiliness. Polyhydroxy Acids (PHAs) have larger molecular structures, making them gentler and suitable for sensitive skin types. Each type of acid offers distinct benefits and can be chosen based on individual skin needs and concerns.

To summarise:

  1. AHAs: These are water-soluble acids derived from fruits and milk. Common examples include glycolic acid (from sugar cane) and lactic acid (from milk). AHAs work on the skin’s surface, gently exfoliating dead skin cells to reveal smoother, brighter skin underneath. They enhance skin texture, reduce the appearance of fine lines, and improve moisture retention.
  2. BHAs: Oil-soluble acids, with salicylic acid being the most notable. BHAs penetrate deeper into the pores, making them effective in treating acne and blackheads. They help exfoliate the skin, unclogging pores and reducing inflammation and redness.
  3. PHAs: Larger molecular structures that don’t penetrate the skin as deeply, making them less irritating. They are suitable for sensitive skin types and provide gentle exfoliation. PHAs also offer antioxidant benefits and can help strengthen the skin’s barrier function.

Understanding these categories and their functions is key to harnessing the full potential of acids in skincare routines.

SourceFruits, milk, sugarsWillow barkMilk, other gentle sources
Skin PenetrationSurface levelDeep (into pores)Surface level (gentler)
Primary BenefitsExfoliation, hydration, anti-agingDeep exfoliation, oil control, acne treatmentGentle exfoliation, moisture retention, antioxidant
Ideal ForDry, sun-damaged, aging skinOily, acne-prone skinSensitive, reactive skin

AHAs (Alpha Hydroxy Acids)


Alpha Hydroxy Acids (AHAs) are a group of natural acids found in various foods and substances. These include glycolic acid from sugar cane, lactic acid from milk, citric acid from citrus fruits, and tartaric acid from grapes. AHAs are primarily celebrated for their exfoliating properties, which are essential for removing dead skin cells from the skin’s surface, leading to a brighter, smoother, and more youthful complexion.

The science behind AHAs lies in their ability to dissolve the bonds that hold dull, dead skin cells on the skin’s surface. When these bonds are broken, the body sheds the skin cells, revealing the newer, more radiant cells beneath.

The Benefits of AHAs

  1. Improved Skin Texture and Tone: AHAs help smooth out rough texture and reduce the appearance of fine lines and wrinkles. Over time, this results in a more evenly textured surface, giving the skin a more refined appearance.
  2. Enhanced Penetration of Skincare Products: By removing the outermost layer of dead skin cells, AHAs increase the skin’s permeability, allowing other skincare products, like serums and moisturizers, to penetrate deeper and work more effectively.
  3. Hydration and Moisture Retention: AHAs have humectant properties, which attract environmental moisture to the skin. This is particularly beneficial for maintaining skin hydration, keeping it plump, and reducing the visibility of fine lines.
  4. Treatment of Hyperpigmentation: Regular use of AHAs can help fade dark spots and hyperpigmentation by accelerating the skin’s natural shedding process, improving the skin tone over time.
  5. Acne and Pore Size Reduction: For those with acne-prone skin, AHAs can help unclog pores and prevent future breakouts. Additionally, they can help minimize the appearance of enlarged pores by keeping them clear and free from blockages.

In Korean skincare, AHAs are often formulated in a way that emphasizes gradual, gentle exfoliation, in line with the Korean beauty ethos of nurturing and maintaining a healthy, balanced skin barrier. K-Beauty products with AHAs are designed to offer a delicate balance between efficacy and gentleness, making them suitable for regular use.

Integrating AHAs into Your Skincare Routine

When incorporating AHAs into your skincare routine, consider the following:

  • Start with Lower Concentrations: If you’re new to AHAs, begin with products with lower acid concentrations to allow your skin to adjust without irritation.
  • Monitor Frequency of Use: Use AHA products once or twice a week, gradually increasing frequency as your skin builds tolerance.
  • Sun Protection is Crucial: AHAs can increase the skin’s sensitivity to UV radiation. Daily use of a broad-spectrum sunscreen is essential to protect the skin from sun damage.
  • Be Mindful of Skin Type: While AHAs are generally safe for all skin types, those with extremely sensitive skin should proceed cautiously. Patch testing and consulting with a dermatologist can help mitigate potential risks.

BHAs (Beta Hydroxy Acids)


Moving on to Beta-Hydroxy Acids (BHAs), these oil-soluble acids offer unique benefits, particularly for oily and acne-prone skin types. Salicylic acid, derived from willow bark, is the most well-known BHA in skincare. Unlike AHAs, BHAs can penetrate the skin’s pores, offering deep exfoliation at both the surface and within the pore lining. This makes BHAs particularly effective in tackling a range of skin concerns.

The Benefits of BHAs

  1. Deep Pore Cleansing: BHAs are exceptional at unclogging pores, making them ideal for managing blackheads, whiteheads, and acne. By penetrating the oil that clogs pores, salicylic acid helps to normalize the lining of the pores, preventing future clogs and breakouts.
  2. Oil Control: BHAs can be a godsend for those with oily skin. Salicylic acid helps regulate sebum production, reducing the overall appearance of oiliness and providing a matte finish to the skin.
  3. Soothing Inflammation: BHAs have natural anti-inflammatory and antibacterial properties, making them suitable for calming inflamed acne and reducing redness and swelling associated with breakouts.
  4. Smoothing Skin Texture: Similar to AHAs, BHAs can smooth the skin’s surface. However, they offer the added benefit of cleaning out the pores, which can improve the overall texture and appearance of the skin.
  5. Anti-Aging Benefits: While they are primarily known for their acne-fighting abilities, BHAs also have anti-aging properties. By promoting exfoliation and stimulating new skin cell growth, they can help diminish the appearance of fine lines and wrinkles over time.

In Korean beauty products, BHAs are often formulated with hydrating and soothing ingredients to balance their exfoliating effects. This results in products that are powerful yet gentle enough for daily use. Korean skincare recognizes the importance of maintaining skin balance; thus, BHAs are incorporated in a way that respects and supports the skin’s natural barrier.

Integrating BHAs into Your Skincare Routine

Incorporating BHAs into your skincare routine, especially within the K-Beauty framework, can significantly improve skin clarity, texture, and overall health. Consider the following:

  • Start slowly: If you are new to BHAs, start with lower-concentration products and gradually increase as your skin builds tolerance.
  • Combine with Hydration: BHAs can be drying, so it’s essential to pair them with hydrating serums or moisturizers to maintain skin hydration.
  • Use Sun Protection: Like AHAs, BHAs increase sun sensitivity. Ensure that you use a broad-spectrum sunscreen to protect your skin from UV damage.
  • Be Cautious with Sensitive Skin: While BHAs are generally well-tolerated, those with extremely sensitive skin should use them cautiously and consult a skincare professional.

PHAs (Polyhydroxy Acids)


Polyhydroxy Acids (PHAs), the gentler cousins of AHAs and BHAs, have recently gained popularity in the skincare world, particularly within Korean beauty routines. PHAs, including ingredients like gluconolactone and lactobionic acid, are known for their large molecular structure. This larger size slows down their penetration into the skin, making them less irritating and suitable for sensitive skin types. Despite their gentle nature, PHAs offer compelling skincare benefits.

The Benefits of PHAs

  1. Gentle Exfoliation: PHAs provide exfoliation similar to AHAs but without the potential for irritation. They gently remove dead skin cells from the surface, promoting a smoother, more radiant complexion.
  2. Enhanced Moisture Retention: PHAs have strong humectant properties, attracting moisture to the skin and locking it in. This hydration boost is particularly beneficial for dry and sensitive skin types.
  3. Strengthening Skin Barrier: By promoting mild exfoliation and hydration, PHAs can help strengthen the skin’s natural barrier function, enhancing its resilience against environmental stressors.
  4. Antioxidant Properties: PHAs possess antioxidant capabilities, protecting the skin from oxidative damage caused by free radicals and environmental pollutants.
  5. Suitable for Sensitive Skin: Due to their gentle nature, PHAs are ideal for those with sensitive or reactive skin. They provide the benefits of chemical exfoliation without the risk of significant irritation.

Integrating PHAs into Your Skincare Routine

By embracing PHAs in your skincare regimen, especially within the K-Beauty context, you can enjoy the benefits of chemical exfoliation in a gentle, skin-friendly manner. PHAs represent a harmonious blend of efficacy and gentleness, catering to various skin types and concerns and embodying the essence of Korean skincare philosophy. When incorporating PHAs into your skincare routine, consider the following:

  • Ideal for Sensitive Skin Types: PHAs are a great starting point for those new to chemical exfoliants or with sensitive skin. Their gentle nature reduces the risk of irritation.
  • Pair with Other Nurturing Ingredients: Look for PHA products formulated with soothing and nourishing ingredients like ceramides, peptides, and hyaluronic acid to enhance skin health.
  • Consistent Use for Best Results: While PHAs are gentle, constant use is vital in achieving noticeable results. They work gradually to improve skin texture and tone.
  • Sun Protection Is Still Essential: Although PHAs are less likely to increase sun sensitivity than AHAs and BHAs, daily sunscreen use remains crucial in any skincare routine.

Combining Acids in a Skincare Routine

Combining different types of skincare acids like AHAs, BHAs, and PHAs in your regimen can be highly beneficial but requires a nuanced approach to avoid skin irritation and achieve optimal results.

In Korean skincare, which emphasizes skin health and balance, layering these acids can enhance their benefits while ensuring the skin remains nourished and protected.

Follow these guidelines to combine acids in your routine:

  1. Understand Acid Interactions: AHAs and BHAs can be used together for a more comprehensive exfoliation, targeting different layers of the skin. However, it’s crucial to understand how your skin reacts to each acid. PHAs, due to their gentleness, can often be paired with either AHAs or BHAs for a more sensitive skin-friendly approach.
  2. Start with the Gentlest Acid: When layering, begin with the gentlest acid (usually a PHA), followed by stronger acids like BHAs or AHAs. This step-wise approach helps in minimizing potential irritation.
  3. Consider Product pH and Concentration: The effectiveness of acids depends partly on their pH level and concentration. Products with similar pH levels can generally be layered more safely. It’s advisable to start with lower concentrations and gradually increase as your skin builds tolerance.
  4. Balance with Hydrating and Soothing Ingredients: Following up with hydrating and soothing ingredients, such as hyaluronic acid, ceramides, or niacinamide, is essential after applying acids. This helps to replenish moisture and soothe the skin, maintaining a healthy skin barrier.
  5. Monitor Skin’s Response: Pay close attention to your skin’s response. Signs of over-exfoliation or irritation include redness, peeling, or heightened sensitivity. If any of these occur, reduce the frequency of acid use or simplify your routine.
  6. Customization for Skin Types: Tailor your acid layering routine to your skin type and concerns. For example, oily and acne-prone skin may benefit more from BHAs, while dry or mature skin might prefer the moisturizing effects of AHAs and PHAs.
  7. Safe Integration into Routine: Introduce acids gradually into your skincare routine, allowing your skin to adjust. Avoid initially combining acids with other potent ingredients like retinoids or vitamin C, which can lead to irritation.

Safety and Precautions When Using Acids

Acids in Kbeauty

Safety and precautions are paramount when incorporating acids like AHAs, BHAs, and PHAs into your skincare routine, especially within Korean skincare’s meticulous and health-focused framework. Understanding the potential side effects and knowing when to seek professional advice is crucial for maintaining skin health and achieving the desired benefits without adverse reactions.

Safely using skincare acids hinges on mindful application, respect for skin tolerance levels, and professional guidance to ensure a harmonious balance between efficacy and skin health. Keep these considerations in mind when using acids:

  1. Recognizing Overuse and Its Effects: Overuse of skincare acids can lead to various skin issues, including excessive dryness, redness, peeling, increased sensitivity, and even burns in severe cases. These symptoms often indicate that the skin’s barrier has been compromised, leaving the skin vulnerable to infections and long-term damage.
  2. Importance of Sun Protection: Acids, particularly AHAs and BHAs, can increase the skin’s sensitivity to UV radiation. Apply a broad-spectrum sunscreen daily and reapply as needed to protect the skin from potential sun damage and prevent the counteraction of the acids’ benefits.
  3. Balancing with Nourishing Ingredients: Incorporating nurturing ingredients like ceramides, peptides, and natural oils in your routine can help offset potential dryness or irritation caused by acids. These ingredients support the skin’s natural barrier and provide hydration and nourishment.
  4. Patch Testing and Gradual Introduction: Before adding a new acid-based product to your routine, conduct a patch test to check for adverse reactions. Gradually introduce acids into your regimen, allowing your skin to build tolerance over time.
  5. Consultation with a Dermatologist: For individuals with sensitive, reactive, or problem skin, consulting a dermatologist before using skincare acids is highly recommended. A skincare professional can provide personalized advice, recommend appropriate products and concentrations, and help address any underlying skin conditions.
  6. Being Cautious with Combinations: Certain combinations of skincare ingredients can be too harsh when used together. For example, combining retinoids with acids may cause significant irritation and should be approached cautiously.
  7. Listening to Your Skin: Pay close attention to how your skin responds to the use of acids. Any signs of discomfort or irritation warrant pausing and reassessing your skincare regimen. Remember, less is often more when it comes to potent ingredients like acids.

The key is to respect your skin’s limits, balance potent acids with soothing and hydrating care, and seek professional guidance when necessary. This approach aligns with Korean skincare’s holistic and mindful ethos, ensuring that your journey with skincare acids is both practical and safe.

Embrace The Power Of Acids In K-Beauty

In Korean skincare, the roles of AHAs, BHAs, and PHAs can be transformative.

With their surface-level exfoliation, AHAs bring forth a brighter, smoother complexion, tackling fine lines and boosting moisture. BHAs delve deeper, unclogging pores and combating acne, a boon for those battling oily skin and breakouts. PHAs, the gentle giants of skincare acids, exfoliate with minimal irritation, making them a safe harbor for sensitive skin types while delivering palpable benefits.

The allure of these acids in K-Beauty lies in their ability to cater to a wide array of skin concerns, offering solutions that are as effective as they are innovative. However, the journey to incorporating these acids into your skincare routine should be approached with mindfulness. It’s crucial to understand your skin type, listen to its needs, and start slowly, mainly if you are new to these ingredients.

Experimentation can lead to discovery, but it should be done cautiously. Patch test, start with lower concentrations and gradually increase usage, allowing your skin to adapt without overwhelming it.

You can genuinely harness the transformative potential of these powerful ingredients by understanding and respecting each acid type’s unique properties and benefits and tailoring their use to individual skin needs.

Remember, skincare is as much about patience and consistency as the ingredients. Embracing acids in K-beauty skincare can improve skin health, marked by radiance, clarity, and vitality.

Scientific Sources To Consult:

Learn everything the ingredients to use in your Korean skincare routine:

Disclaimer: Please note that the images accompanying this article have been created with the assistance of artificial intelligence (AI). While designed to enhance the content and provide a visual representation, they may not be replicas of real-world entities or products. AI-generated images are synthetic and are used for illustrative purposes only.

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