Understanding Face Acids: How to Choose the Right Acid for Your Skin Type and Skin Concern

Whenever one thinks of the word “acid,” it brings up images of chemical burns or bubbling liquids in vials. However, acids that are used on the skin are of the different kind and when they are used in the correct manner in the right concentrations, they can lead to lot of benefits to the skin.

Facial acids when used in the right manner can be miracle tools for fighting skin concerns, such as wrinkles, acne, age spots, skin texture uneven skin tone and scarring.^{(1, 2)} However, with the amount of acids available in the market, it can become overwhelming to understand and to know which to use and when to use and for what purpose to use. In this article, we will talk about the different types of facial acids and how they can be used depending on the skin type and skin concern.

All the face acids (except for hyaluronic acid) are exfoliants, meaning that they shed the topmost lining of the dead skin so that the new skin cells surface faster. By doing this, it also results in brighter and smoother skin along with unclogging pores and fighting acne. Some facial acids are great for antiaging and also help in preventing and reversing skin damage, such as age spots, redness and wrinkles.

In skin care, there are two main kinds of acids used:

• Alpha Hydroxy Acids (AHAs): These are the water-soluble acids, which loosen the fluid that bonds skin cells on the surface together. By doing this, the dead skin cells can easily slough off.
• Beta Hydroxy Acids (BHAs): These are oil-soluble acids, which can penetrate deeper into the skin pores than AHAs and help in exfoliating the dead skin cells. Due to their oil dissolving ability, they can dissolve sebum, which helps in preventing and treating acne.

However, not all skin care acids belong to these categories. A good example would be hyaluronic acid.

Skin Type: All skin types.

Skin Concern: Dull, dehydrated, dry skin, mature skin.

Hyaluronic acid is not an AHA or BHA, but it is a sugar molecule. Hyaluronic acid is naturally produced by the human body and it has a slippery and goopy texture that helps in retaining moisture, hydrating and lubricating the body including your eyes, joints and skin.

Topical application of hyaluronic acid makes the skin look hydrated and plump. As one gets older, the production of hyaluronic acid in the body decreases resulting in dry skin and loss of elasticity in the skin making it more prone to fine lines and wrinkles. Hyaluronic acid suits every skin type and does not cause irritation and it is present in almost all the skin care products.

Skin Type: Oily and acne prone skin.

Skin Concern: Clogged pores, acne, whiteheads and blackheads.

Salicylic acid is one of the oldest facial acids known to dermatologists. It is known for its ability to unclog the skin pores and exfoliate the skin, which in turn helps in fighting and preventing acne. ⁽³⁾ Salicylic acid can be found in cleansers and serums at concentrations between 0.5 and 2 percent. They are also utilized in spot treating a pimple. Salicylic acid is also a good skin care ingredient for preventing blackheads and whiteheads.

Salicylic acid is used in higher concentrations to act as a peeling agent for treating acne scars, acne, sun damage, melasma and age spots by dermatologists. Salicylic acid is also used in solutions to remove corn and warts. As salicylic acid is related to aspirin (acetylsalicylic acid), it also contains anti-inflammatory properties.

Skin Type: Combination skin, mature skin.

Skin Concern: Pigmented skin, texture, fine lines, acne and acne scars.

Glycolic acid belongs to the category of alpha-hydroxy acid (AHA) and is one of the smallest AHA and is derived from sugar cane. Because of its size, it effectively penetrates the skin. Glycolic acid is extremely popular as it makes for an incredible anti-aging agent which is also good for exfoliating the skin and decreasing fine lines, reducing dark spots, preventing acne, increasing the thickness of the skin, and evening out the skin texture and tone.⁽⁴⁾ The common concentration of Glycolic acid which is found in many popular skin care is under 10 percent.

Glycolic acid is also used in chemical peels, which is basically exfoliation of the skin on a deeper level for acne treatment and fading pigmentation, and sometimes along with microneedling or microdermabrasion.

Skin Type: All skin types.

Skin Concern: Acne, redness, inflammation, dull skin.

Azelaic acid is one of the popular treatments for fighting moderate acne in the last 30 years and is used in many prescription-only creams. The benefits of using Azelaic acid is clearing the pores on the skin, reducing inflammation and destroying the bacteria. This acid is usually found in 15 to 20 percent concentrations in creams that are made such to be used on the entire face; be it in morning and night. There are very few side effects of Azelaic acid; however, in some individuals who have extremely sensitive skin, it can cause peeling stinging and redness.

Other than for treating and preventing acne, azelaic acid is also used as a skin-lightening and brightening agent beneficial in reducing post-inflammatory hyperpigmentation or post-acne marks.⁽⁵⁾ It is often used in conjunction with retinoids as a gentler alternative to hydroquinone.

Skin Type: Dry skin, sensitive skin.

Skin Concern: Skin pigmentation and acne prevention.

Mandelic acid also belongs to the group of alpha-hydroxy acid and is one of the gentlest skin acids that is derived from bitter almonds. It is also an exfoliating agent used for treating and preventing acne, evening out pigmentation and treating sun damage. However, Mandelic acid has a larger molecular structure and so cannot penetrate the skin as deeply as the glycolic acid does, but in this way also causes less irritation to the skin. For this reason, Mandelic acid is recommended more so for ethnic skin that is more vulnerable to rebound pigmentation in peels instead of glycolic acid.⁽⁶⁾ Rebound pigmentation develops when the skin develops resistance to a particular substance with increased use leading to not only inefficacy of the product, but also will have the opposite effect instead of the desired one.

Skin Type: All skin types except for sensitive skin.

Skin Concern: Dull skin, tanned skin, pigmentation on the skin.

Kojic acid is produced by bacteria which is used in rice fermentation to make sake. Due to its anti-aging and whitening properties Kojic acid is a popular ingredient in Asian skin care products.⁽⁷⁾

It is also used in serums and cleansers at 1 to 4 percent concentrations. However, despite it being a very effective it can also be irritating to skin.

Skin Type: Suitable for all skin types except for acne prone and sensitive skin.

Skin Concern: To brighten dull looking skin, melasma, pigmented skin, scars and antiaging.

Ascorbic is one of the most common water-soluble types of vitamin C, which is used in skin care for its brightening and anti-aging effects. It is commonly used as a hydroquinone substitute in melasma treatment.⁽⁸⁾ In the presence of water and oxygen, ascorbic acid can be very unstable, so it is usually available in stabler forms as magnesium tetra-isopalmitoyl and ascorbyl phosphate ascorbic acid.

Note of Caution: All the skin care acids are exfoliants and all of them make the skin more sensitive. So, it is imperative to apply sunscreen with a minimum SPF of 50 when out in the sun to protect your skin.

Other skin care acids that are available in the market are citric, lactic, tartaric and malic acids.

After glycolic acid, lactic acid is one of the best researched AHA, and is known for being more hydrating, gentler and more effective in treating skin that is sun damaged. ⁽⁹⁾

Ferulic acid is another skincare acid, which acts as an antioxidant ingredient commonly used along with vitamins C and E in skin care serums.

Lipoic acid is also an antioxidant ingredient that has lot of anti-aging benefits; however, not as good as other skin care acids due to which it is not that well known.

Alguronic acid is a byproduct of biodiesel production and reportedly seems to have anti-aging effects, however, more research is needed on it.

Trichloroacetic acid (TCA) is commonly used in peels and is beneficial for flattening out scars in the TCA cross technique.⁽¹⁰⁾ Due to its potent nature, trichloroacetic acid should only be used by professionals.

Linoleic acid and oleic acid when discussed in skin care, their names usually come under the category of oils, where they are not considered actual acids per se, but as fatty acids that in presence of oils react such that they lose their acid groups resulting in formation of triglycerides. Commonly, oils that have more of linoleic acid tend to have drier textures suitable for oily skin, and oils having more of oleic acid are richer and are considered more suitable for dry skin.

Deciding on which acid to use for which problems and skin type needs lot of knowledge, experience and expertise, which your dermatologist has. One should first identify which problem to treat then decide, which acid is best for treating that skin care problem.

For concerns, such as acne-prone skin, the best acids to use are azelaic acid, glycolic acid, salicylic acid, mandelic acid and lactic acid.

For mature skin, the best choices will be lactic acid, glycolic acid, ascorbic acid and ferulic acid.

For fading pigmentation, the best skin care acids are kojic acid, glycolic acid, azelaic acid, linoleic acid, lactic acid, ascorbic acid and ferulic acid.

Note of Caution: Always patch test before starting on any skin care acid and always use them in the dosage and percentage as recommended by the doctor. As increased concentrations of these acids will only cause irritation of the skin.

Never ever mix face acids. Mixing facial acids can cause lot of harm to the skin. A few examples of the harm will be using salicylic acid with any acid at the same time can lead to excessive irritation of the skin.

The use of salicylic acid should also be avoided with products having niacinamide in them.

Never use AHAs with retinol.

Never use lactic or glycolic acid in combination with ascorbic acid as doing this will decrease the efficacy of the ascorbic acid.

Never use facial acids in higher concentration than what is needed, thinking that you will get better and faster results, as it will only cause skin irritation, redness, peeling etc. If the concentration of the acid needs increasing, then your dermatologist is the best person to decide this.

To balance using more than one acid in your skin care routine one should allot a time for them to be used, such as salicylic acid can be used in the morning skin care routine and glycolic acid in the nighttime skincare routine. This way, your skin will get the benefits of both of the acids without the added irritation and treat more than one skin concern.

When used in the right way in the right concertation, acids can be a great tool to fight against a myriad of skin problems, such as acne, wrinkles, uneven skin tone, clogged pores, whitehead, blackheads, skin texture, sun damage and so much more. So, do not hesitate and do not fear skin care acids and if you are having any skin problem, consult a dermatologist to find out the best acid for treating your skin concern.

References: