Skin exfoliants form a major part of the cosmetic industry. Hydroxy acids are a vital component in most chemical exfoliants. Hydroxy acids target various skin problems and improve the appearance of the skin.
The two most common types of hydroxy acids that are used in exfoliants are AHA and BHA.
AHA vs BHA
The difference between AHA and BHA is that AHA is a stronger and more aggressive chemical compound while BHA is a comparatively less stronger chemical compound. The full form of AHA is Alpha Hydroxy Acids while the full form of BHA is Beta Hydroxy Acids.
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AHA is a water-soluble acid. The compound consist of carboxylic acid and the adjacent carbon is substituted with a hydroxyl group. The separation of the two functional groups is by one carbon atom.
Apart from cosmetic usage, AHA is also considered a prebiotic molecule and is linked with the origin of life under suitable conditions.
While BHA oil-soluble acids. The compound consists of carboxylic acid and hydroxy as a functional group. However, two carbon atoms separate the hydroxy group. The pH level of BHA exfoliants is between 3.2 to 3.9.
Comparison Table
| Parameters of Comparison | AHA | BHA |
|---|---|---|
| Full form | AHA stands for Alpha Hydroxy Acids | BHA stands for Beta Hydroxy Acids |
| Arrangement of groups | The separation of the two functional groups is by one carbon atom | The separation of the two functional groups is by two carbon atoms |
| Hydrogen bridging | The intramolecular hydrogen bridge is easily formed in the compound because of shorter distance | The intramolecular hydrogen bridge is not so easily formed in the compound, because of the larger distance |
| Types | Five main types of AHA are glycolic acid, malic acid citric acid, lactic acid, and tartaric acid | Four main types of BHA are salicylic acid, beta hydroxybutanoic acid, tropic acid, and trethocanic acid |
| Application | It is used to treat hyperpigmentation, fine lines, wrinkles, large pores, melasma, and other scars | It is used to treat acne, sun damage, remove excess oil, dead skin, unclog the pores, and reduction of rosacea-related redness |
What is AHA?
AHA stands for Alpha Hydroxy Acids. The chemical compounds consist of carboxylic acid and the adjacent carbon is substituted with a hydroxyl group.
The compound can occur naturally or can be synthetic. The primary use of AHA is in the cosmetic industry. The form that is used is bacterial, synthetic, or derived from fungal fermentations.
AHA is widely used in products that help in the reduction of wrinkles, fine lines and are also used as chemical peels on the skin. The compound reaches the vascular dermis of the skin and works on the targeted region.
AHAs are also used for keratinization. The process includes the formation of a new stratum corneum. The compound can modulate the cohesion between corneocytes.
AHAs with other ingredients like glycolic acid, citric acid, lactic acid can work on deeper dermal effects. The combination can promote collagen and increase the thickness of the skin. AHAs also protect the skin from Ultraviolet(UV) rays.
The compound is also used in organic synthesis as precursors. AHA is considered a prebiotic molecule and is linked with the origin of life under suitable conditions.
Various over-the-counter products contain AHA at low concentrations usually between 5 – 10% and are used for monotherapy or skincare management.
The higher concentrations that contain 10 – 50% of AHA are used to prime and prepare the skin for stronger chemical concentrations or applications.
A concentration of 50 – 70% of AHA is prescribed by physicians to treat photo-damaged skin or acne-prone skin.
What is BHA?
BHA stands for Beta Hydroxy Acids. It is an organic compound with carboxylic acid and hydroxy as a functional group. However, two carbon atoms separate the hydroxy group.
BHA is also known as salicylic acid, especially in the cosmetic industry. Removal of a water molecule from BHA produces alpha-beta unsaturated acid.
BHA forms the active ingredient in treatments that involve anti-aging or acne-prone skin. It can also effectively reduce the inflammation of the skin.
Apart from the common salicylic acid, beta hydroxy acids can be of various other types like beta-hydroxybutyric acid, beta hydroxy beta methyl butyric acid, carnitine, and others.
The compound has a high absorbance rate and is actively absorbed when applied topically. The pH level of BHA exfoliants is between 3.2 to 3.9.
The skin treatments containing BHA target to reduce the appearance of large pores, reduce skin texture, remove dead skin cells and provide an even skin tone. BHA has antibacterial effects and hence is best for skin treatments on acne-prone skin.
BHA can cause photosensitivity. So, BHA products can make the skin sensitive to the sun. Wearing sunscreen and other coverups during the skin treatment which includes BHA, is essential.
BHAs are oil-soluble acids so they work best in combination with oily skin to absorb the excessive sebum. Skin products containing BHA should not be applied to infants and small children.
Main Differences Between AHA and BHA
- AHA is a stronger chemical compound while BHA is a comparatively less strong chemical compound.
- AHA are water-soluble acids while BHA oil-soluble acids.
- AHA has a low absorbance rate and works on the upper layer of the skin while BHA has a high absorbance rate and works on the deeper layers of the skin.
- AHA is best for normal to dry skin while BHA is best for combination to oily skin.
- AHA is produced from sugary fruits while BHA is mainly produced synthetically.
- https://www.sciencedirect.com/science/article/pii/S0016236106001967
- https://www.sciencedirect.com/science/article/pii/S221137971930230X
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Chara Yadav holds MBA in Finance. Her goal is to simplify finance-related topics. She has worked in finance for about 25 years. She has held multiple finance and banking classes for business schools and communities. Read more at her bio page.
