Glycolic or Salicylic Acid: Which Type Should You Choose?

Glycolic acid, derived from sugarcane, belongs to the family of alpha-hydroxy acids (AHAs). AHAs are characterized by their hydroxyl group (-OH) being attached to the carbon atom adjacent to the carboxylic acid group (-COOH), which is what defines them as "alpha." This structure makes glycolic acid highly water-soluble and effective in aqueous environments.

Its small molecular size enables it to easily penetrate the skin's protective barrier, specifically targeting the uppermost layer, known as the stratum corneum. Here, glycolic acid breaks down the bonds between dead skin cells, facilitating their removal and promoting a smoother, more radiant complexion. By exfoliating the surface layer, glycolic acid also supports better absorption of other skincare ingredients and can help stimulate collagen production over time. These combined properties make glycolic acid an effective solution for the following:

• Dull Skin: By removing dead skin cells, glycolic acid reveals fresher, more radiant skin beneath.

• Fine Lines and Wrinkles: Regular use can help reduce the appearance of fine lines and improve skin texture by boosting collagen levels.

• Hyperpigmentation: It evens out skin tone and fades dark spots through consistent exfoliation.

Who Should Use Glycolic Acid?

Glycolic acid is suited for all skin types, but best for individuals with normal to dry skin, particularly those looking to target signs of aging or improve skin texture and tone. In daily skin products, it is most commonly found in concentrations ranging anywhere from 2% to 10%.

Salicylic acid, a beta-hydroxy acid (BHA), is characterized by its oil-soluble nature and its unique chemical structure. Unlike alpha-hydroxy acids, salicylic acid's hydroxyl group is attached to the second carbon atom from the carboxyl group—hence the "beta." This structure, combined with its phenolic ring, makes salicylic acid lipid-loving, allowing it to dissolve easily in the skin's natural oils.

This oil-solubility helps salicylic acid penetrate deep into clogged pores, breaking down excess sebum and dead skin cells. Derived from willow bark, its most commonly recommended for:

• Acne and Breakouts: Its ability to dissolve oil makes it ideal for clearing clogged pores, which can help reduce acne and prevent future breakouts.

• Oily Skin: Salicylic acid helps regulate excess oil production, which is beneficial for those with oily or combination skin types. So, if you are experiencing overactive sebaceous glands and excess sebum production, salicylic acid might just be the solution for you.

• Blackheads and Whiteheads: By exfoliating inside the pores, salicylic acid helps remove impurities and prevent open (blackheads) and closed comedones (whiteheads).

Who Should Use Salicylic Acid?

Salicylic acid is generally recommended for people with oily or combination skin and those who struggle with mild to moderate acne. It is commonly available in over-the-counter products at low concentrations, typically between 0.5-2%, to reduce the risk of dryness or irritation.

This topic has been well-researched, with numerous studies exploring the effects of different acids on skin concerns. One such study, compared glycolic acid and a combination peel containing salicylic acid on a group of 45 patients with active acne (grade 1 and 2) and post-acne pigmentation. Participants were divided into two groups of 15, with Group A using 35% glycolic acid peels and Group B using 20% salicylic acid peels. Both groups underwent 3-minute peeling sessions biweekly for 12 weeks, with a photographic record taken at each follow-up.

The results indicate that salicylic acid was more effective overall, particularly in reducing pustular lesions and comedones. It also performed equally well in improving post-acne pigmentation, showing its efficacy in treating both active acne and its aftermath. 

Other studies confirm these findings, such as the one by SEKHAR V. & al. (2023), which involved 200 patients with acne scars and hyperpigmentation. In this split-face observational study, salicylic acid peels showed significantly better responses than glycolic acid peels. The study concluded that salicylic acid is not only effective for acne and hyperpigmentation but is also safe for treating conditions like melasma, photodamage, freckles, and lentigines, particularly in darker skin types.

Glycolic and salicylic acids offer similar benefits at lower concentrations, in which they are available in daily skincare products, such as improving skin texture by light exfoliation, brightening the complexion, and treating mild acne—making them good for at-home use. However, for more severe cases like persistent acne, higher concentrations are often needed, and research shows that salicylic acid, with its oil-soluble properties, is particularly effective for this purpose.

While both acids offer exfoliation benefits, salicylic acid is better suited for getting deep into clogged pores and treating oily and acne-prone skin, whereas glycolic acid works by removing dead skin cells and has found its place in targeting hyperpigmentation, improving skin texture, and offering fine-line reduction through collagen stimulation.

When using these acids at higher concentrations, such as in high concentrated chemical peels, it is crucial to seek the expertise of a professional to avoid potential skin damage and achieve the best results. For at-home use, we recommend introducing these acids gradually, performing a patch test, staying away from the sun, and closely monitoring your skin's response to maximize their benefits and avoid irritation.

• SHARAD J. Glycolic acid peel therapy: A current review. Clinical, Cosmetic, and Investigational Dermatology (2013).

• ARIF T. Salicylic acid as a peeling agent: A comprehensive review. Clinical, Cosmetic, and Investigational Dermatology (2015).

• GARG V. K. & al. Comparative study of 35% glycolic acid, 20% salicylic–10% mandelic acid, and phytic acid combination peels in the treatment of active acne and postacne pigmentation. Journal of Cutaneous and Aesthetic Surgery (2019).

• MUKOVOZOV I. & al.. Topical AHA in dermatology: Formulations, mechanisms of action, efficacy, and future perspectives. Cosmetics (2023).

• SEKHAR V. & al. Comparative evaluation of glycolic acid and salicylic acid peels followed by PRP for treatment of hyperpigmentation: A split face study. Journal of Dental Specialities (2023).