Exfoliation Guide: AHAs, BHAs, PHAs - What Are They and How Do They Work in The Skin?

Exfoliation Guide: AHAs, BHAs, PHAs - What Are They and How Do They Work in The Skin?

AHAs, PHAs, and BHAs are all types of exfoliating acids commonly used in skincare. However, they differ in their chemical structure, properties, and effects on the skin.

AHAs, or alpha-hydroxy acids, are water-soluble acids that work by breaking down the bonds between dead skin cells on the surface of the skin. The most common AHAs used in skincare are glycolic acid and lactic acid, which are known for their ability to exfoliate and brighten the skin. AHAs are generally considered safe for most skin types, but they can be irritating to sensitive skin or if used in high concentrations.

PHAs, or polyhydroxy acids, are a newer type of acid that are similar to AHAs but have a larger molecular size. This means they penetrate the skin more slowly and are less likely to cause irritation or inflammation. PHAs are also water-soluble and work by breaking down the bonds between dead skin cells, but they also have hydrating and antioxidant properties, making them a good choice for those with sensitive or dry skin.

BHAs, or beta-hydroxy acids, are oil-soluble acids that work by penetrating deep into the pores and breaking down the oil and debris that can cause acne and blackheads. The most common BHA used in skincare is salicylic acid, which is known for its ability to unclog pores and reduce inflammation. BHAs are generally recommended for those with oily or acne-prone skin, but they can be drying or irritating if used in high concentrations or on sensitive skin.

Overall, the main difference between AHAs, PHAs, and BHAs is their chemical structure, which determines their properties and effects on the skin. AHAs are water-soluble and exfoliate the skin, PHAs are similar to AHAs but have a larger molecular size and also have hydrating and antioxidant properties, and BHAs are oil-soluble and work to unclog pores and reduce inflammation. It is important to choose the right type of acid for your skin type and concerns and to use them as directed to avoid irritation or other adverse effects.

What are Alpha Hydroxy Acids and How they Work in the Skin

Alpha hydroxy acids (AHAs) are a group of compounds that are derived from fruit, milk, and other natural sources. They are commonly used in skincare products to exfoliate the skin and improve the appearance of fine lines, acne scars, and uneven skin tone. There are 8 types of alpha hydroxy acids and a brief explanation of how they work in the skin:

Glycolic acid

However, it's important to note that glycolic acid can be harsh on the skin if not used properly. It is recommended to start with a lower concentration and gradually increase over time, and to always use sunscreen when using glycolic acid products as they can increase skin sensitivity to the sun. It is also recommended to consult a dermatologist before incorporating glycolic acid into your skincare routine, especially if you have sensitive skin.

Lactic acid

Lactic acid is a type of alpha-hydroxy acid (AHA) that is naturally produced by the body during exercise and metabolism. It is also commonly used in skincare products due to its exfoliating properties.

In skincare, lactic acid works by breaking down the bonds between dead skin cells on the surface of the skin, which helps to remove them and reveal smoother, brighter, and more youthful-looking skin. Unlike some other AHAs, such as glycolic acid, lactic acid is generally considered to be gentler on the skin, making it a popular choice for those with sensitive skin.
In addition to its exfoliating effects, lactic acid also has moisturizing properties. It helps to attract and retain moisture in the skin, which can help to improve skin texture and reduce the appearance of fine lines and wrinkles.
Lactic acid may also have other benefits for the skin. It has been shown to help improve the appearance of acne-prone skin, reduce the appearance of dark spots and hyperpigmentation, and improve overall skin tone and texture.
Mandelic acid is a type of alpha-hydroxy acid (AHA) that is derived from bitter almonds. It is a colorless, crystalline solid that is commonly used in skincare products due to its exfoliating properties.
In skincare, mandelic acid works by breaking down the bonds between dead skin cells on the surface of the skin, which helps to remove them and reveal smoother, brighter, and more youthful-looking skin. It also helps to unclog pores and reduce the appearance of acne and blackheads.

Mandelic acid

Mandelic acid is considered to be a gentle AHA, making it a good choice for those with sensitive skin. It has larger molecules than other AHAs, such as glycolic acid and lactic acid, which means it penetrates the skin more slowly and is less likely to cause irritation.
In addition to its exfoliating effects, mandelic acid has been shown to have antibacterial and anti-inflammatory properties, which can be helpful for those with acne-prone skin. It also helps to improve the appearance of fine lines and wrinkles and may help to reduce the appearance of dark spots and hyperpigmentation.

Hydroxycaproic acid

Hydroxycaproic acid, also known as 2-hydroxy-6-aminocaproic acid, is a naturally occurring alpha-hydroxy acid (AHA) that is found in royal jelly. It is a colorless crystalline solid that is commonly used in skincare products due to its exfoliating properties.

In skincare, hydroxycaproic acid works by breaking down the bonds between dead skin cells on the surface of the skin, which helps to remove them and reveal smoother, brighter, and more youthful-looking skin. It also helps to unclog pores and reduce the appearance of acne and blackheads.

Hydroxycaproic acid is considered to be a relatively mild AHA, making it a good choice for those with sensitive skin.

What are PHA's and How Do They Work?

The most common PHAs (polyhydroxy acids) used in skincare are:

Gluconolactone 

a gentle exfoliant and antioxidant that helps to hydrate and improve the skin's barrier function. It is often used in formulations for sensitive skin.
Lactobionic acid - a larger molecule PHA that works similarly to AHAs, but is gentler and has additional antioxidant and anti-inflammatory properties. It is often used in anti-aging and brightening formulations.

Galactose 

A type of sugar that has humectant properties and helps to attract moisture to the skin. It also has antioxidant properties and can help to improve skin texture and radiance.

Maltobionic acid 

A larger molecule PHA that is similar to lactobionic acid, but with slightly stronger exfoliating properties. It is often used in formulations for mature skin or those with hyperpigmentation.

Glucuronic acid 

A sugar acid that is a precursor to hyaluronic acid, a key component of the skin's natural moisturizing factor. It helps to hydrate and plump the skin, and also has antioxidant properties.

PHAs are considered to be a gentler alternative to AHAs, as they have a larger molecular size and penetrate the skin more slowly, reducing the risk of irritation or inflammation. They are also hydrating and have antioxidant properties, making them a good choice for those with sensitive or dry skin, or those who are new to using exfoliating acids.

What are BHA's and How Do They Work?

BHAs (beta-hydroxy acids) are a type of exfoliating acid that work by penetrating deep into the pores to break down the oil and debris that can cause acne and blackheads. The most common BHA used in skincare is salicylic acid, which is derived from willow bark and has anti-inflammatory and antibacterial properties in addition to its exfoliating benefits.

Salicylic acid is oil-soluble, which means it can penetrate through the oil and sebum that clog pores and cause acne. Once it enters the pore, it works to dissolve the sebum and dead skin cells that are trapped inside, helping to unclog the pore and prevent further breakouts. Salicylic acid also has anti-inflammatory properties, which can help to reduce redness and irritation associated with acne.

BHAs are particularly effective for those with oily or acne-prone skin, as they can help to regulate sebum production and reduce the formation of new breakouts. They can also be beneficial for those with blackheads or enlarged pores, as they help to remove the buildup of dead skin cells and debris that can make pores appear larger.

It is important to note that BHAs can be drying or irritating if used in high concentrations or on sensitive skin. It is recommended to start with a low concentration of salicylic acid and gradually increase as tolerated, and to use it as directed to avoid over-exfoliation or other adverse effects. Additionally, BHAs can increase skin sensitivity to the sun, so it is important to use sunscreen daily when using these types of acids.

Acids Used In Skincare That Do Not Exfoliate

There are several acids used in skincare that do not have exfoliating properties, but instead, provide other benefits to the skin. Here are a few examples:

Hyaluronic acid 

A humectant acid that helps to attract and retain moisture in the skin, promoting hydration and plumping the skin.

Azelaic acid 

A dicarboxylic acid that has anti-inflammatory and anti-bacterial properties, making it effective for treating acne and rosacea.

Ferulic acid 

A plant-derived acid that has antioxidant properties, protecting the skin from free radicals and environmental stressors.

Kojic acid 

A fungal-derived acid that has skin-lightening properties, making it effective for treating hyperpigmentation and age spots.

Linoleic acid 

An omega-6 fatty acid that helps to strengthen the skin's barrier function and improve skin texture.

Ascorbic acid (vitamin C) 

Although one of the most popular skincare ingredients, Ascorbic Acid is a fairly unstable synthetic antioxidant acid that brightens and evens out the skin tone, and promotes collagen production for a more youthful appearance.

Tranexamic acid

A synthetic amino acid that has been used for many years in medicine to control bleeding and prevent blood clots. In recent years, it has also gained popularity in skincare due to its ability to address hyperpigmentation and uneven skin tone.

Tranexamic acid works by blocking the production of melanin, which is the pigment that gives color to the skin. When there is an overproduction of melanin, it can result in hyperpigmentation or dark spots.

Tranexamic acid helps to inhibit this process by blocking the enzyme responsible for melanin production, thereby reducing the appearance of dark spots and improving overall skin tone. In addition to its skin brightening benefits, tranexamic acid also has anti-inflammatory properties and can help to reduce redness and inflammation associated with acne and other skin conditions.

Polyglutamic acid (PGA)

A naturally occurring peptide that is produced by bacteria, and it has been found to have several benefits when applied to the skin. One of the main functions of PGA is its ability to act as a humectant, meaning that it helps to attract and retain moisture in the skin.

PGA has been shown to be even more effective than hyaluronic acid, another popular humectant, at retaining moisture in the skin. This makes PGA a great ingredient for hydrating and plumping the skin and can be particularly beneficial for those with dry or dehydrated skin.

What are the Best Alpha Hydroxy Acids for Each Skin Type?

The best alpha hydroxy acid (AHA) for a particular skin type will depend on a variety of factors, including the individual's skin concerns, sensitivity, and concentration of the AHA. Here are some general guidelines for choosing the best AHA for different skin types:

• Oily skin: Glycolic acid and Salicylic Acid are both good c for oily skin, as they can help to reduce excess oil and improve the appearance of acne. Earth Harbor Luna Rain Night serum contains sugar cane, which is the natural form of glycolic acid. This l formula also contains a medley of seaweed collagen, tropical superfruit acids, and botanical multivitamins that give the skin a smoother and more radiant appearance. 

• Dry skin: Lactic acid is a good choice for dry or sensitive skin, as it is less irritating and more hydrating than other AHAs. Agent Nateur Holi Bright contains Lactic acid along with hydrating ingredients such as aloe vera and hyaluronic acid. This brightening mask offers deep hydration while gently resurfacing the skin and improving skin texture.

• Sensitive skin: Mandelic acid is a good choice for sensitive skin, as it is gentle and has a larger molecule size, which makes it less likely to cause irritation. Versine Gentle Actives Clarity serum contains Mandelic acid and superstar ingredients such as Vitamin C and niacinamide. This multi-tasking serum minimizes the appearance of hyper-pigmentation, fine lines, and dry and fatigued skin. It is also safe to use during pregnancy!

• Acne-prone skin: Salicylic acid is a good choice for acne-prone skin, as it can help to unclog pores and reduce the appearance of acne. Formulated with plant-derived salicylic acid One Love Organic Botanical A serum effectively exfoliates the skin while hydrating it. It also has Brazilian purple clay which draws out impurities and dead skin cells.

• Sun-damaged skin: Tetrahexyldecyl Ascorbate (THD), also known as Vitamin C, is a good choice for sun-damaged skin, as it can help to improve the appearance of uneven skin tone and fine lines. Kari Gran Vitamin C serum is formulated with concentrated, stable, waterless 10% vitamin C along with an organic antioxidant super blend, of plum seed, cloudberry, and lingonberry oils. This serum protects the skin against free radicals and treats hyperpigmentation and uneven skin tone.

It's important to note that AHAs and BHA's can cause irritation, redness, and dryness in some individuals, so it's important to use them carefully and according to the instructions on the product label. It's also a good idea to start with a lower concentration of AHA and gradually increase the strength as your skin becomes accustomed to it.   

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