Can You Over-Exfoliate Skin with Acids? Chemical exfoliation produces some of the most dramatic results you can get with at-home skincare treatments. Next to sunscreen, it’s the most difference-making product in your skincare routine. But can you take things too far and what happens if you exfoliate too much? It’s possible… if you don't take the time to experiment and see which strength of exfoliant and frequency of use works best for your skin. Don’t let that intimidate you—with proper usage of gentle yet effective exfoliating acids, you will see the impressive benefits of chemical exfoliation, without hurting your skin. Here’s everything you need to know to safely exfoliate your skin. The importance of a gentle exfoliant Gentle means no irritants, such as high amounts of harsh, drying alcohol, menthol that makes skin tingle, and fragrance (whether synthetic or natural essential oils). Gentle also means that the formula should contain soothing agents that keep skin in a calm, healthy state while the exfoliators go to work. Examples of skin-soothing ingredients include allantoin, bisabolol, green tea extract, and oat extract, just to name a few. Notice we keep repeating the word gentle. That’s because your exfoliant doesn’t need to be harsh on skin to work. Quite the contrary—when properly formulated, exfoliating acids should leave your skin in a calm, healthy state. And don’t forget that gentle formulas are important for all of your skincare products, not just the exfoliants. What about those who are prone to having sensitive skin… can they still use a chemical exfoliant? Yes, in this case, a calming 1% BHA is an optimal choice (BHA has natural soothing properties). But prior to that... Avoid severly over exfoliated skin and ditch abrasive exfoliating scrubs If you’ve been using an abrasive scrub, stop immediately. Harsh scrubs abrade and erode at skin’s barrier, ultimately leaving skin in a weaker state. Research shows physical scrubs aren’t as effective and lack the additional benefits chemical exfoliants can provide, such as hydrating skin (yes you read that right, exfoliating acids can increase hydration), reducing breakouts, and minimising the appearance of wrinkles and discolorations (1,2,3). What concentration should I look for in a chemical exfoliant? There are three main categories of at-home chemical exfoliators available: alpha hydroxy acid (AHA), beta hydroxy acid (BHA), and poly hydroxy acid (PHA). Each has a recommended concentration range for best results. For regular use (think daily or every few days depending on your skin’s needs), AHAs and PHAs are generally recommended in concentrations between 4-10% (4). For BHA (salicylic acid), up to 2% is considered best for regular use and for acne exfoliants. Higher concentrations of these hydroxy acids can be helpful for stubborn concerns, but that’s where extra precaution and attention comes into play. For instance, high-strength 9% BHA can be used as an occasional spot treatment to reduce stubborn bumps. What about combinations of exfoliating acids formulated into one product, resulting in a higher strength overall? If the product was carefully formulated to minimise risk of irritation, this kind of exfoliant can work well to target advanced concerns, with the caveat that this should be limited to less frequent usage (once a week max) and in a rinse-off format instead of being left on skin overnight. We repeat, do not use this kind of at-home, peel-strength exfoliant daily. *In-office chemical peel treatments are a whole other topic. Please consult your dermatologist for more information. Does pH matter for chemical exfoliants? Along with choosing a gentle formula that contains skin-soothing ingredients, the pH of your chemical exfoliant is crucial. It can make or break the formula and how your skin responds to it. For acid-based exfoliants, the optimal pH range for safe, effective use is between 3 and 4. Using highly acidic (lower pH values) or highly alkaline (pH 8 or greater) products can cause a significant disruption in skin’s barrier. This is how some chemical exfoliants on the market cause trouble for your skin. How do you know what the pH of your exfoliant product is? Reputable brands will list this information on the packaging or their website. If they don’t, you can call the company to ask. If all else fails, you can buy pH strips to test it yourself (inconvenient but an option nonetheless). How often should I use exfoliating acids? If you’re new to using hydroxy acid exfoliants, it’s smart to introduce them into your routine slowly. For initial use, that means spacing out application to only two or three times the first week. If your skin does well (no signs of distress), you can gradually increase frequency of use up to twice a day. Twice per day application can be a game changer if you have more stubborn bumps, clogs, acne-prone skin or advanced signs of sun damage. Others will find once daily or even once every few days usage is their skin’s sweet spot. It will take some experimenting to find the right cadence. Special tip for those with acne: it can take frequent application in the beginning to get skin under control. You may find you can scale back to every few days for maintenance or you may need ongoing daily use to keep skin in the clear. It truly depends on what your skin needs and how it responds, which is why there is no hard and fast rule. Does chemical exfoliation damage skin’s barrier? Studies have shown that well-formulated AHAs and PHAs do not damage skin's barrier (6). Instead, they disrupt the bonds that are holding dead cells to skin's surface, allowing them to shed like they once did. Moreover, research has shown that topical use of AHAs and PHAs can actually strengthen skin's barrier health (7). Likewise, there isn’t concern with BHA exfoliants when properly formulated and used correctly. Because BHA is lipid/oil soluble, it can get past skin's barrier without harming it, while still ungluing the bonds of dead skin on the surface. Bonus, this oil solubility also allows it to unclog congested pores (8). That said, if the product is not well-formulated in the ways discussed above, all bets are off. Sensitised skin is absolutely a possibility. Are chemical exfoliants safe to use long term? Exfoliating acids have a proven track record (we’re talking decades) of safe use in cosmetics (4,5). If the product is well-formulated and used as directed, there is no concern with a long-term commitment. As is recommended for any skincare routine, follow with sunscreen (SPF 30 or greater) to keep skin protected from the short- and long-term visible effects of sun damage. Learn more about exfoliation.
References for this information: Dermatology Research and Practice, February 2015, pages 1-5 Dermatology and Therapy, March 2015, pages 1–18 International Journal of Research in Engineering, Science and Management, October 2020, pages 1-2 International Journal of Toxicology, 2017, pages 15S-21S The Cosmetic Ingredient Review, April 2019, pages 1-60 International Journal of Cosmetic Science, April 2021, pages 1-13 Journal of Investigative Dermatology, February 2010, pages 500-510 American Journal of Clinical Dermatology, 2003, pages 473-492