What is the difference between AHA, BHA, and PHA? Anyone who examines skincare ingredient lists has likely encountered these three abbreviations. These chemical exfoliant groups help remove dead skin cells from the skin’s surface and can support improvements in texture and radiance when used appropriately. However, each acid group works differently and interacts with the skin in distinct ways. Their effects vary depending on the skin type, its needs, and its tolerance.
In this article, I explain the scientific characteristics of AHA, BHA, and PHA; their differences; and how they interact with different skin structures—strictly for informational purposes, in line with medical advertising regulations.
What Are AHAs? (Alpha Hydroxy Acids)
AHAs are water-soluble acids, often derived from fruits.
Common AHA types include:
- Glycolic acid
- Lactic acid
- Mandelic acid
- Malic acid
- Citric acid
How AHAs Act on the Skin
AHAs primarily work on the surface of the skin, contributing to:
- Removal of superficial dead skin cells
- A more even-looking skin tone
- Reduction in dullness
- A more radiant and smooth appearance
Because they are water-soluble, AHAs are often used in formulas researched for dry or dehydrated skin types.
Which Skin Types Commonly Use AHAs?
- Dry skin
- Dull or tired-looking skin
- Uneven skin texture
- Superficial tone irregularities
Different AHAs penetrate the skin at different rates depending on their molecular size.
For example, mandelic acid has a larger molecule and is often better tolerated by sensitive skin.
What Are BHAs? (Beta Hydroxy Acids)
BHAs are oil-soluble acids.
The most widely known BHA is salicylic acid.
Because they dissolve in oil, BHAs can interact more effectively with sebum accumulated inside pores.
How BHAs Act on the Skin
They can help dissolve excess oil inside pores
They are frequently researched in blackhead- and whitehead-prone skin
They help reduce surface texture irregularities
They are of particular interest for skin with shifting oil balance
For these reasons, BHAs are commonly used on oily and acne-prone skin.
Which Skin Types Commonly Use BHAs?
- Oily skin
- Visible pores
- Blackhead tendency
- Excess sebum in the T-zone
BHAs also have mild anti-inflammatory properties, which may help them be better tolerated by some sensitive skin types.
What Are PHAs? (Polyhydroxy Acids)
PHAs have larger molecular structures compared with AHAs and BHAs.
The main PHA types are:
- Gluconolactone
- Lactobionic acid
- How PHAs Act on the Skin
- PHA characteristics include:
- Gentle exfoliation
- Surface renewal without excessive dryness
- Support for moisture retention
- A more barrier-friendly mechanism
Because PHA molecules are larger, they penetrate more slowly, making them suitable for sensitive or barrier-impaired skin.
Which Skin Types Commonly Use PHAs?
- Sensitive skin
- Redness-prone skin
- Atopic-like barrier features
- Rosacea-prone reactive skin
- Skin experiencing dryness or barrier weakness
PHAs are often researched as a gentler alternative when AHAs or BHAs are not well tolerated.
What Are the Differences Between AHA, BHA, and PHA?
Below is a general comparison of the three acid groups:
| Feature | AHA | BHA | PHA |
| Solubility | Water-soluble | Oil-soluble | Water-soluble |
| Target Area | Skin surface | Inside pores | Surface + barrier-friendly |
| Primary Effect | Tone & radiance | Sebum & pores | Gentle renewal & hydration |
| Commonly Used For | Dry / dull skin | Oily/congested skin | Sensitive/barrier-weak skin |
| Molecule Size | Small - medium | Medium | Large (Gentler penetration) |
This table is for informational purposes only; every individual’s skin structure is unique, and proper evaluation must be made by qualified healthcare professionals.
Can AHA, BHA, and PHA Be Used Together?
Theoretically, some skin types may tolerate combinations. However, using multiple exfoliants can lead to:
- Excessive exfoliation
- Barrier weakening
- Increased sensitivity
- Redness and irritation
Therefore, product combinations, application frequency, and suitability should only be determined by authorized dermatology professionals.
How Does Chemical Exfoliation Affect the Skin?
Chemical exfoliants work by influencing the bonds between dead skin cells, helping them shed more easily. This mechanism can support:
- A smoother skin texture
- Reduced dullness
- A more uniform surface appearance
However, overuse can weaken the lipid barrier, which may lead to:
- Redness
- Dryness
- Irritation
- Stinging sensations
- Sensitivity
- Moderation and skin-appropriate application are key.
Which Acid Is Commonly Used in Which Situation?
1. AHAs
Surface dullness, texture irregularities, lack of radiance.
2. BHAs
Oil buildup, congestion, blackhead tendency.
3. PHAs
Sensitivity, barrier weakness, poor tolerance to AHA/BHA.
Frequently Asked Questions
Which is more effective: AHA or BHA?
Neither is “more effective” universally; each works differently depending on the skin’s needs.
Which exfoliant is gentler for sensitive skin?
PHAs are generally better tolerated.
Do BHAs really work inside the pores?
Yes—because they are oil-soluble, they can interact with sebum more effectively.
Do AHAs remove dark spots?
Medical claims cannot be made; however, AHAs can support a more even appearance by helping renew the surface.
Can AHA and BHA be used together?
It depends on the individual’s skin tolerance and should be evaluated by professionals.
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