Part 2 of our 3-Part article:
- Exfoliating Skin Care Acids
- What does pH have to do with a skin care acid’s effectiveness?
- Moisturizing Acids – no bite, all love
Choosing an over the counter (OTC) or cosmetic product that contains Alpha Hydroxy Acid (AHA) or Beta Hydroxy Acids (BHA) doesn’t have to be a daunting task.
There are 3 primary factors to consider when choosing an acidic ingredient in your skin care products.
- What do acids do for the skin?
- What does pH have to do with a skin care acid’s effectiveness? What is the percentage of the active acid(s) in the product?
- Moisturizing vs Exfoliating Acids
What does pH have to do with it?
Potential Hydrogen (pH) is a measure of how acidic or alkaline a substance is. Acids have pH values under 7.
Why should we measure a product’s pH?
Our skin’s Acid Mantle is a protective chemical layer made up of sebum (free fatty acids) from the skin's sebaceous (oil) glands, mixed with lactic and amino acids from perspiration. The skin’s acid mantle should register at about a 5.5 pH. The pH of your skin’s acid mantle determines its ability to protect your skin from insults such as bacteria, viruses, free radicals and environmental pollutants that contribute to premature aging, surface disease and irritation. If a product is too alkaline, it may be irritating and drying and not possess the characteristics that we look for in an acidic formulation that contains glycolic, lactic, salicylic, azelaic or mandelic acids.
Cosmetic and over the counter (OTC) skin care products meant for home use contain a lower percentage of acid in their formulas than professional chemical peels and often times, a higher Potential Hydrogen (pH) value. This adjustment makes the products functionally less acidic and safe for frequent and ongoing use.
The Cosmetic Ingredient Review (CIR) Expert Panel, the industry's self-regulatory body for reviewing the safety of cosmetic ingredients, concluded in 1998 that Glycolic and Lactic Acid are safe for use in cosmetic products at concentrations of:
- For home use
- ≤10% Acid in final formulation with a pH ≥3.5
- For Professionally applied products
- ≤30%, at final formulation pH ≥3.0 designed for brief, discontinuous use followed by thorough rinsing of the skin
- Application must be accompanied by directions for the daily use of sun protection or product must be formulated to avoid increasing sun sensitivity
Each pH testing packet will have a unique color key code.
Here is an example of pH strip reader. Water is neutral at a 7pH.
- 3 to 4 pH is a common level of acidity in topical AHA/BHA skin care formulations from a skin care professional. Since a professional can view the client’s skin and recommend products based on their knowledge of both the science and an individual’s skin, the lower pH can be safe and highly effective.
- 8 – 8 pH is common for mass marketed drugstore products that contain AHAs or BHA. Commercial cosmetics may be more alkaline, making them less acidic and less potent for safety reasons.
- 5 pH is a typical measure of a healthy skin’s Acid Mantle. After washing with an alkaline cleanser and water with a pH of 7, we may lower the pH by use of a toner, serum or a moisturizer with a pH around 5.5.
Are all products with the same percentage of acid equal in strength?
A 2% AHA or BHA ingredient would have more potency if it was in a 3.8 pH formula base than if it is in a formula with a pH of eight. The higher pH base, perhaps a moisturizer or hydrating serum, would neutralize the acid in the final product. Thus, not all products with the same percentage of active ingredients are equally as potent! Unfortunately, dishonest product distributors may use misleading marketing strategies in order to sell products based on popular ingredients that they include in their products. The question a consumer needs to answer is whether or not the acidic ingredients are active or neutralized. Using pH strips to test a product’s pH or consulting the product’s manufacturer are the best way to know the pH of a skin care product.
If you use an acid in your skin care routine, you must be diligent in use of an effective sun block! Acids can make your skin more vulnerable to the sun’s rays and sun damage and burns can occur if you are not properly protected. Both AHAs and BHAs can cause irritation including redness, burning, pain or itching. Darker skinned individuals may also be at risk for scarring and loss of pigment when using acids. Consult a skin care professional to determine if acids will be your friend or a foe to be avoided! Wear your sunblock and re-apply regularly!
Ali, S. M., & Yosipovitch, G. (2013). Skin pH: from basic science to basic skin care. Acta dermato-venereologica, 93(3), 261-269.
Issachar, N., Gall, Y., Borfll, M. T., & Poelman, M. C. (1997). pH measurements during lactic acid stinging test in normal and sensitive skin. Contact Dermatitis, 36(3), 152-155.
Parra, J. L., & Paye, M. (2003). EEMCO guidance for the in vivo assessment of skin surface pH. Skin Pharmacology and Physiology, 16(3), 188-202.
Schmid-Wendtner, M. H., & Korting, H. C. (2006). The pH of the skin surface and its impact on the barrier function. Skin pharmacology and physiology, 19(6), 296-302.Van Scott, E. J., & Ruey, J. Y. (1980). U.S. Patent No. 4,234,599. Washington, DC: U.S. Patent and Trademark Office.