Alpha hydroxy acids (AHAs) are a group of naturally occurring acids found in various fruits, sugars, and milk. While not technically classified as medical substances, they are widely used in dermatological and cosmetic applications for their exfoliating and skin-renewing properties.
Here's a breakdown of AHAs:
Types:
- Glycolic acid: Derived from sugarcane, it's the strongest and most commonly used AHA, effective for deeper exfoliation.
- Lactic acid: Found in sour milk, it's gentler than glycolic acid and suitable for sensitive skin.
- Malic acid: Present in apples, it offers mild exfoliation and is often used in combination with other AHAs.
- Citric acid: Found in citrus fruits, it has mild exfoliating and brightening effects.
- Tartaric acid: Derived from grapes, it primarily acts as a humectant (attracts moisture) and offers mild exfoliation.
How they work:
AHAs work by loosening the bonds between dead skin cells on the outermost layer of the skin (stratum corneum), promoting their shedding and revealing the fresher, smoother skin underneath. This process also stimulates collagen production and cell turnover, leading to various benefits.
Applications:
- Exfoliation: AHAs remove dead skin cells, resulting in a brighter, smoother, and more even skin tone.
- Acne treatment: They can help unclog pores and reduce breakouts, especially when used in combination with other acne-fighting ingredients.
- Anti-aging: AHAs stimulate collagen production, potentially reducing the appearance of fine lines and wrinkles.
- 改善色素沉着 (gài shàn sè sù chén zhú) (Improving hyperpigmentation): They can help fade dark spots and hyperpigmentation caused by sun damage or other factors.
Important to note:
- AHAs can make skin more sensitive to sunlight, so sun protection with SPF 30 or higher is crucial when using them.
- Start with a low concentration and patch test on a small area of your skin before applying to your entire face, as they can cause irritation, especially for sensitive skin.
- Consult with a dermatologist if you have concerns or pre-existing skin conditions before using AHAs.
Overall, while not strictly medical substances, AHAs offer a range of benefits for skin health and are widely used in dermatological and cosmetic applications. However, it's essential to be aware of their potential side effects and use them with caution, especially if you have sensitive skin.