Salicylic acid (SA) and glycolic acid (GA) are two of the most popular chemical exfoliants used in skincare to improve texture, tone, and clarity. The idea of combining these powerful ingredients to address multiple concerns simultaneously is appealing. While using them together offers a comprehensive approach to exfoliation, it requires a deliberate and cautious strategy to prevent irritation and maintain skin health. This dual exfoliation can be highly effective, but only when executed with an understanding of each acid’s function.
How Salicylic and Glycolic Acids Work
Salicylic acid is classified as a beta hydroxy acid (BHA), which means its chemical structure makes it oil-soluble. This property allows SA to penetrate deep into the pore lining, where it dissolves trapped sebum and dead skin cells. This oil-dissolving action provides a comedolytic effect, making it effective for treating blackheads, whiteheads, and acne. Salicylic acid also possesses anti-inflammatory properties, which helps to reduce the redness and swelling associated with breakouts.
Glycolic acid, by contrast, is an alpha hydroxy acid (AHA) and is water-soluble, meaning it works primarily on the skin’s surface. Its small molecular size allows it to weaken the bonds (desmosomes) that hold dead skin cells together in the stratum corneum. GA facilitates the shedding of the outermost layer of dull skin cells, a process called desquamation. This action improves overall skin texture, brightens the complexion, and helps to fade surface discoloration and fine lines.
Safe Strategies for Combining Both Acids
Combining these two acids requires careful planning to maximize benefits without causing excessive irritation or compromising the skin barrier. Simultaneous use, such as layering two potent leave-on products, is generally too harsh for most users and should be avoided. The goal is to alternate their application to ensure the skin receives the benefits of both surface and deep exfoliation over time.
Alternating Application
One of the safest methods involves alternating the acids on different days or times of the day. For example, a user might apply a glycolic acid product on Monday night for surface renewal and a salicylic acid product on Wednesday night for pore cleansing. Alternatively, an experienced user might use a salicylic acid cleanser in the morning to control oil and a low-concentration glycolic acid toner at night for brightness.
Zoning
A strategy known as zoning involves applying each acid to different, targeted areas of the face based on the skin’s needs. Salicylic acid can be reserved for the T-zone, jawline, or other areas prone to congestion and oiliness. Glycolic acid can then be applied to the cheeks and forehead, areas that often benefit more from surface smoothing and tone improvement. This method prevents over-processing areas that only require one type of exfoliation.
Combining Product Types
Another method involves combining rinse-off and leave-on products to control the contact time and concentration of the acids. This could involve using a cleanser containing one acid, such as a salicylic acid wash, followed by a leave-on serum or moisturizer with a low concentration of the other acid. When layering leave-on products, it is recommended to apply the oil-soluble salicylic acid first to penetrate the pores, followed by the water-soluble glycolic acid for surface treatment.
Identifying and Managing Over-Exfoliation
Over-exfoliation occurs when the skin barrier is damaged by the overuse of chemical exfoliants. Recognizing the early signs of damage is important to prevent further complications. A common symptom is persistent redness that does not fade quickly after application, or a stinging and burning sensation when applying normally tolerated, non-active products.
The skin may also develop an unusually tight, dry, or waxy appearance. This appearance is often mistaken for a healthy glow but indicates the premature exposure of underlying skin. Paradoxically, over-exfoliated skin can sometimes lead to increased oil production as the skin attempts to compensate for the stripped natural oils, or it may result in clusters of small, bumpy breakouts.
If over-exfoliation is suspected, the immediate step is to stop using all active ingredients, including both salicylic and glycolic acids, as well as retinoids. The focus must shift entirely to soothing and barrier repair. This recovery phase involves using bland, gentle cleansers and rich moisturizers containing ingredients like ceramides, hyaluronic acid, and glycerin to restore hydration and the lipid barrier. Consistent application of a broad-spectrum sunscreen with an SPF of 30 or higher is also necessary, as compromised skin is highly susceptible to sun damage.