AHA vs BHA vs PHA: What's the Difference & Which Exfoliating Acid Is Right for Your Skin?

Written by Mohd Aalim
Performance Marketing Executive & SEO Content Strategist at QTWAYS

Reviewed by QTWAYS Research Team

Last Updated: July 2026

Disclaimer: This article is for educational purposes only and should not replace professional medical advice. If you have eczema, rosacea, severe acne, an impaired skin barrier, or another skin condition, consult a qualified dermatologist before introducing exfoliating acids into your skincare routine

Introduction

Walk into any skincare aisle or browse products online, and you'll quickly come across terms like AHA, BHA, and PHA. They're often described as exfoliating acids that promise smoother skin, brighter complexion, fewer breakouts, and improved texture.

But choosing between them can be confusing.

Some products recommend AHA for glowing skin, others claim BHA is the answer for acne, while newer formulas highlight PHA as the gentle alternative for sensitive skin.

So which one is actually right for you?

The truth is that there isn't one exfoliating acid that's best for everyone. Each acid works differently because of its chemical properties, the layer of skin it targets, and the skin concerns it's designed to address.

Choosing the right exfoliating acid depends on your:

• Skin type
• Primary skin concern
• Skin sensitivity
• Previous experience with chemical exfoliation
• Overall skincare routine

Understanding these differences can help you choose products that match your skin's needs instead of simply following trends.

In this guide, you'll learn:

• What AHA, BHA, and PHA actually are
• How each exfoliating acid works
• The differences between Glycolic, Lactic, Mandelic, and Salicylic Acid
• Which acid suits different skin types and concerns
• Whether you can combine exfoliating acids
• Common mistakes to avoid
• How to choose an exfoliating routine safely

---

What Are Exfoliating Acids?

Your skin naturally sheds dead skin cells through a process known as desquamation. As we age—or due to factors like sun exposure, excess oil production, or environmental stress—this process can slow down.

When dead skin cells accumulate, they may contribute to:

• Dull-looking skin
• Rough texture
• Clogged pores
• Blackheads
• Uneven skin tone
• A less radiant complexion

Exfoliation helps remove these dead surface cells, allowing newer skin cells to become more visible.

There are two main ways to exfoliate:

Physical Exfoliation

Physical exfoliants use particles or tools to manually remove dead skin cells.

Examples include:

• Face scrubs
• Cleansing brushes
• Exfoliating gloves

While they can provide an immediate smooth feeling, excessive friction may irritate the skin, especially if used too aggressively.

---

Chemical Exfoliation

Chemical exfoliants don't rely on scrubbing.

Instead, they work by loosening the bonds that hold dead skin cells together, allowing them to shed more evenly.

This often results in a more uniform and controlled exfoliation compared to harsh physical scrubs.

The three main categories of chemical exfoliating acids are:

• AHA (Alpha Hydroxy Acid)
• BHA (Beta Hydroxy Acid)
• PHA (Polyhydroxy Acid)

Although all three help exfoliate the skin, they behave differently because of differences in their chemistry.

---

AHA vs BHA vs PHA: Quick Comparison

If you're looking for a quick answer, here's a simplified comparison.

In simple terms:

• Choose AHA if your main concerns are dullness, uneven skin tone, or rough texture.
• Choose BHA if excess oil, blackheads, or clogged pores are your biggest concerns.
• Choose PHA if you have sensitive skin or you're new to chemical exfoliation.

Remember, these are general guidelines. The right choice also depends on the product formulation and your skin's individual tolerance.

---

What Is an AHA (Alpha Hydroxy Acid)?

AHAs are water-soluble exfoliating acids that work primarily on the surface of the skin.

They help loosen the connections between dead skin cells, allowing them to shed more evenly and revealing fresher skin underneath.

Because they focus on the outer layer of the skin, AHAs are often recommended for concerns related to skin texture and appearance rather than excess oil inside pores.

AHAs May Help Improve:

• Dull-looking skin
• Uneven texture
• Fine lines
• Sun-related skin changes
• Post-inflammatory pigmentation
• Mild discoloration

AHAs are commonly chosen by people with:

• Dry skin
• Normal skin
• Combination skin
• Mature skin

---

Common Types of AHAs

Not all AHAs are the same.

Each one has unique characteristics.

Glycolic Acid

Derived originally from sugar cane, Glycolic Acid has one of the smallest molecular sizes among commonly used AHAs.

Because of its small size, it can penetrate the skin relatively efficiently, making it popular for improving:

• Rough texture
• Uneven skin tone
• Dullness
• Fine lines

People with sensitive skin may find higher concentrations of Glycolic Acid more stimulating than other AHAs.

---

Lactic Acid

Lactic Acid provides surface exfoliation while also acting as a humectant, meaning it helps attract moisture to the skin.

It is often preferred by people with:

• Dry skin
• Mild sensitivity
• Dehydrated skin
• First-time AHA users

Many people find it gentler than Glycolic Acid, although individual tolerance varies.

---

Mandelic Acid

Mandelic Acid has a larger molecular size than Glycolic Acid.

Because it penetrates more slowly, it is often considered a gentler AHA option.

It's commonly used by people concerned with:

• Uneven texture
• Mild acne
• Post-acne marks
• Combination skin

Its slower penetration may make it a suitable introduction to AHAs for some beginners.

---

Why Not All AHAs Feel the Same

One of the biggest misconceptions in skincare is treating all AHAs as if they're identical.

In reality, molecule size influences how quickly an acid penetrates the skin.

Generally speaking:

• Smaller molecules may penetrate more readily.
• Larger molecules tend to penetrate more gradually.

This is one reason why Glycolic Acid and Mandelic Acid can feel quite different on the skin, even though both belong to the AHA family.

However, the overall experience also depends on factors such as concentration, formulation, pH, and supporting ingredients.

What Is a BHA (Beta Hydroxy Acid)?

Unlike AHAs, BHAs (Beta Hydroxy Acids) are oil-soluble exfoliating acids. This means they can mix with the skin's natural oils (sebum), allowing them to exfoliate not only the skin's surface but also inside oil-filled pores.

Because of this property, BHAs are widely used in skincare products designed for oily and acne-prone skin.

The most commonly used BHA in skincare is Salicylic Acid.

---

How Does BHA Work?

Excess oil, dead skin cells, and debris can build up inside pores over time.

This congestion may contribute to:

• Blackheads
• Whiteheads
• Enlarged-looking pores
• Acne breakouts

Salicylic Acid helps exfoliate the inside of pores by loosening dead skin cells and reducing the buildup that can lead to congestion.

Unlike surface-only exfoliation, BHAs work where oily skin often needs the most attention.

---

BHAs May Help Improve

• Blackheads
• Whiteheads
• Oily skin
• Congested pores
• Acne-prone skin
• Uneven skin texture caused by clogged pores

People with oily or combination skin often benefit from incorporating a BHA into their routine, provided it's used according to the product instructions.

---

Salicylic Acid: The Most Common BHA

When people refer to a BHA, they're usually talking about Salicylic Acid.

Salicylic Acid has become one of the most researched exfoliating ingredients because of its ability to work within pores while also exfoliating the skin's surface.

It's commonly found in:

• Cleansers
• Serums
• Spot treatments
• Toners
• Peeling solutions

The concentration, pH, and overall formulation influence how the product performs, so two Salicylic Acid products may feel very different despite containing the same ingredient.

---

What Is a PHA (Polyhydroxy Acid)?

PHAs (Polyhydroxy Acids) are often described as the gentlest family of chemical exfoliating acids.

Like AHAs, PHAs are water-soluble, but they have a larger molecular size.

Because larger molecules generally penetrate the skin more slowly, PHAs tend to be associated with a lower likelihood of irritation compared with stronger exfoliating acids.

This makes them a popular choice for:

• Sensitive skin
• First-time acid users
• Reactive skin
• People looking for gentle exfoliation

---

How Does PHA Work?

PHAs exfoliate the skin's surface in a similar way to AHAs, helping remove dead skin cells and improve skin texture.

However, many PHAs also function as humectants, meaning they help attract and retain moisture in the skin.

This combination of gentle exfoliation and hydration support is one reason they're often recommended for people who find stronger acids difficult to tolerate.

---

PHAs May Help Improve

• Mild roughness
• Dull-looking skin
• Uneven texture
• Sensitive skin routines
• Beginner exfoliation routines

Although PHAs are generally gentler, they're still active exfoliating ingredients and should be used according to the product's instructions.

---

Common Types of PHAs

The two most common PHAs found in skincare are:

Gluconolactone

Known for providing mild exfoliation while helping support hydration.

---

Lactobionic Acid

A larger PHA that combines gentle exfoliation with moisture-retaining properties.

Both are commonly included in formulations intended for sensitive or compromised skin.

---

AHA vs BHA vs PHA: What's the Real Difference?

Many skincare articles simply say:

• AHA = Dry Skin
• BHA = Oily Skin
• PHA = Sensitive Skin

While that's a useful starting point, it doesn't explain why they behave differently.

The main differences come down to three factors:

1. Solubility
2. Molecule size
3. Target area of the skin

---

1. Solubility

AHAs

Water-soluble.

Primarily work on the skin's surface.

---

BHAs

Oil-soluble.

Can mix with sebum and exfoliate inside oil-filled pores.

---

PHAs

Water-soluble.

Work mainly on the skin's surface while penetrating more gradually than many AHAs.

---

2. Molecule Size

Although molecule size isn't the only factor affecting an acid's performance, it does influence how readily an ingredient moves into the skin.

Smaller molecules aren't automatically "better."

The ideal choice depends on your skin goals and tolerance.

---

3. What They Target

Each acid solves a different problem rather than competing with one another.

---

Glycolic vs Lactic vs Mandelic vs Salicylic Acid

Understanding individual acids helps you choose products more confidently.

Each ingredient offers unique strengths, and no single acid is universally superior.

---

Which Exfoliating Acid Is Right for Your Skin?

Instead of asking:

"Which acid is the strongest?"

Ask:

"Which acid matches my skin's needs?"

If Your Main Concern Is Dullness

Choose an AHA, particularly Glycolic Acid or Lactic Acid.

These acids help improve surface texture and radiance by exfoliating dead skin cells.

---

If You Have Oily Skin or Blackheads

A BHA, such as Salicylic Acid, is often the better option because it can exfoliate within oil-filled pores.

---

If You Have Sensitive Skin

A PHA or a gentler AHA like Mandelic Acid may be more suitable, depending on your skin's tolerance and the product formulation.

---

If You Have Dry Skin

Lactic Acid is frequently recommended because it combines exfoliation with humectant properties that help support hydration.

---

If You're New to Chemical Exfoliation

Start with:

• PHA
• Mandelic Acid
• Lower-strength AHA products

Introduce exfoliating acids gradually and monitor how your skin responds.

---

Quick Decision Guide

---

Can You Use AHA, BHA, and PHA Together?

Yes—but the answer depends on how they're combined.

There's an important difference between:

• Layering multiple acid products in the same routine, and
• Using a professionally formulated product that combines different acids in balanced proportions.

Applying several exfoliating products one after another can increase the risk of over-exfoliation, redness, and barrier irritation.

In contrast, some rinse-off peels and leave-on treatments are specifically formulated to combine multiple acids because each ingredient serves a different purpose. The formulation—including acid type, concentration, pH, and supporting ingredients—is designed to work as a complete system rather than as separate layers.

This is why formula design matters just as much as the ingredient list.

---

Why Some Products Combine Multiple Acids

No single exfoliating acid addresses every skin concern.

For example:

• Glycolic Acid helps improve dullness and uneven texture.
• Lactic Acid exfoliates while supporting hydration.
• Mandelic Acid provides gentler surface exfoliation.
• Salicylic Acid targets congested, oil-filled pores.

A thoughtfully designed multi-acid formula can address several concerns at once without relying on just one ingredient.

The QTWAYS 30% AHA + 2% BHA Peeling Solution follows this formulation philosophy by combining Glycolic Acid, Lactic Acid, Mandelic Acid, and Salicylic Acid. Instead of depending on a single exfoliating acid, it uses multiple acids with complementary roles. To support skin comfort after exfoliation, the formula also includes D-Panthenol (Vitamin B5), Aloe Vera, Chamomile, Calendula, and Green Tea Extract.

This highlights an important skincare principle:

The effectiveness of an exfoliating product depends not only on the acid percentage, but also on the overall formulation, pH, supporting ingredients, and how consistently it's used.

Common Myths About AHA, BHA & PHA

There are plenty of misconceptions about exfoliating acids. While these ingredients can be highly effective, using them based on myths rather than evidence may lead to unnecessary irritation or disappointing results.

Let's separate fact from fiction.

---

Myth 1: Stronger Acids Always Give Better Results

Reality:
A higher concentration doesn't automatically make an exfoliating product more effective.

The performance of an acid depends on several factors, including:

• The type of acid
• The product's pH
• Contact time (for rinse-off products)
• Supporting ingredients
• Your skin's tolerance

A well-formulated product with balanced ingredients often performs better than a high-strength formula that's too irritating for regular use.

Healthy skin comes from consistent exfoliation—not aggressive exfoliation.

---

Myth 2: You Need to See Visible Peeling

Many people believe that if their skin isn't visibly peeling, the product isn't working.

This isn't true.

Chemical exfoliation works at a microscopic level by encouraging the removal of dead skin cells. You may notice smoother texture or a brighter complexion without experiencing obvious flaking.

Visible peeling is not a requirement for effective exfoliation.

---

Myth 3: Oily Skin Doesn't Need Moisturizer

Some people avoid moisturizing after using exfoliating acids because they're worried about making oily skin feel greasier.

In reality, moisturizing helps support the skin barrier after exfoliation.

Skipping moisturizer may leave your skin feeling tight or irritated and, in some cases, may even contribute to increased oil production as the skin tries to compensate for water loss.

---

Myth 4: More Frequent Exfoliation Means Faster Results

Exfoliating every day isn't necessarily better.

Your skin needs time to recover between exfoliation sessions.

Using acids too frequently can lead to:

• Redness
• Dryness
• Increased sensitivity
• Tightness
• Temporary barrier disruption

Consistency and moderation usually produce better long-term results than over-exfoliation.

---

Myth 5: You Can't Use Different Acids Together

Different exfoliating acids can work together when they're part of a professionally formulated product.

The concern arises when people layer multiple exfoliating products without considering the overall acid load.

A balanced formulation differs significantly from mixing several acid products in the same routine.

---

Common Beginner Mistakes

Even a well-formulated exfoliating product can cause problems if it's used incorrectly.

Here are some of the most common mistakes beginners make.

---

Using Too Many Active Ingredients Together

Applying an exfoliating acid alongside retinoids, other acids, physical scrubs, or strong acne treatments in the same routine may increase irritation.

When introducing an exfoliating acid, keep the rest of your routine simple until your skin adjusts.

---

Ignoring Patch Testing

Every person's skin responds differently.

A patch test can help identify sensitivity before applying the product to your entire face.

It's a small step that can prevent unnecessary discomfort.

---

Leaving the Product On Longer Than Recommended

Leaving a rinse-off peel on for extra time won't necessarily improve your results.

Instead, it increases your exposure to the acids and may increase the chance of irritation.

Always follow the manufacturer's instructions.

---

Skipping Sunscreen

Exfoliation reveals newer skin cells, making daily sun protection especially important.

A broad-spectrum sunscreen with SPF 30 or higher helps protect your skin from UV exposure and supports better long-term skincare results.

---

Chasing Higher Percentages

Many shoppers assume that a higher acid percentage automatically means a better product.

However, skincare formulation is much more complex than a single number on the label.

A balanced formula considers:

• Acid selection
• Concentration
• pH
• Vehicle
• Supporting ingredients
• Intended frequency of use

This is why experienced formulators focus on the entire formula, not just one headline ingredient.

---

How Often Should You Use AHA, BHA, or PHA?

There's no universal schedule that suits everyone.

The right frequency depends on:

• Your skin type
• Your experience with exfoliating acids
• The specific product
• The acid concentration
• How your skin responds

As a general approach:

• Beginners: Introduce exfoliating acids gradually and observe your skin's response.
• Sensitive skin: Start slowly and avoid increasing frequency too quickly.
• Experienced users: Follow the manufacturer's instructions and adjust only if your skin tolerates it well.

If you notice persistent redness, burning, excessive dryness, or peeling, reduce frequency and allow your skin time to recover.

---

What Should You Avoid Pairing with Exfoliating Acids?

To reduce the risk of irritation, avoid combining exfoliating acids in the same routine with other potentially irritating products unless advised by a dermatologist.

These may include:

Keeping your routine simple after exfoliation often gives your skin the best opportunity to recover.

---

Frequently Asked Questions (FAQs)

Which is better: AHA, BHA, or PHA?

None is universally better.

• AHA is generally suited to dullness, uneven texture, and dry skin.
• BHA is often preferred for oily, acne-prone skin and clogged pores.
• PHA is typically the gentlest option for sensitive skin and beginners.

The best choice depends on your skin type, concerns, and tolerance.

---

Is PHA gentler than AHA?

Generally, yes.

Because PHAs have a larger molecular size, they penetrate the skin more slowly and are often associated with less irritation than many AHAs.

---

Can I use AHA, BHA, or PHA every day?

It depends on the product and your skin's tolerance.

Some gentle leave-on products may be formulated for frequent use, while stronger exfoliating treatments—especially rinse-off peels—are intended to be used less often.

Always follow the manufacturer's directions.

---

Which acid is best for blackheads?

Salicylic Acid (a BHA) is commonly recommended because its oil-soluble nature allows it to exfoliate within oil-filled pores, helping reduce blackheads over time.

---

Which acid is best for dry skin?

Lactic Acid is often a good option because it exfoliates while also providing humectant properties that help support hydration.

---

Is Glycolic Acid stronger than Lactic Acid?

Glycolic Acid has a smaller molecular size, which generally allows it to penetrate the skin more readily. However, the overall strength of a product also depends on its formulation, pH, concentration, and how it's used.

---

Which acid is best for sensitive skin?

PHAs are generally considered the gentlest family of exfoliating acids.

Mandelic Acid may also be suitable for some people because of its relatively slower penetration compared with smaller-molecule AHAs.

---

Can exfoliating acids help with acne marks?

Regular exfoliation may gradually improve the appearance of post-acne marks by supporting skin renewal. Results vary depending on the type of mark, your routine, and consistent sun protection.

---

Do exfoliating acids thin your skin?

No. When used appropriately, exfoliating acids remove dead skin cells from the outermost layer of the skin. They do not "thin" healthy skin in the way this myth often suggests. Overuse, however, can temporarily weaken the skin barrier and lead to irritation.

---

Can beginners use exfoliating acids?

Yes. Beginners should choose products suitable for their skin type, patch test first, introduce acids gradually, and follow the manufacturer's instructions.

---

Conclusion

AHA, BHA, and PHA all belong to the family of chemical exfoliating acids, but each serves a different purpose.

• AHA focuses on improving surface texture, dullness, and uneven skin tone.
• BHA targets oil-filled pores, making it a common choice for oily and acne-prone skin.
• PHA provides gentle surface exfoliation while supporting hydration, making it well suited for sensitive skin and first-time users.

Rather than asking which acid is "the strongest," focus on which one aligns with your skin's needs.

Equally important is the overall formulation. The type of acid, its concentration, pH, supporting ingredients, and how consistently you use the product all influence your results.

This is why products like the QTWAYS 30% AHA + 2% BHA Peeling Solution combine Glycolic Acid, Lactic Acid, Mandelic Acid, and Salicylic Acid instead of relying on a single exfoliating acid. Each ingredient contributes differently, while Panthenol, Aloe Vera, Chamomile, Calendula, and Green Tea Extract help support skin comfort after exfoliation.

Ultimately, successful exfoliation isn't about choosing the strongest acid—it's about choosing the right acid, in the right formulation, and using it consistently with proper aftercare.