When to Introduce Them into Your Skincare Routine and Which Acid to Choose for Your Skin Type
Acids in skincare are often the magical ingredient that makes your skin brighter, smoother, and more radiant, with that coveted “glow” effect. But when should you introduce them, and which acid is best for your skin type?
MET+ has the answers.
Let’s clarify right away: when we say "acid," we mean "exfoliation," specifically chemical exfoliation, so we won’t discuss other acid-based skincare ingredients like hyaluronic acid or vitamin C (ascorbic acid). The most well-known chemical exfoliants in cosmetics are alpha-hydroxy acids (AHAs), beta-hydroxy acids (BHAs), and poly-hydroxy acids (PHAs).
Patented in 1974 for use in topical products for dry skin, acids exploded in popularity in the 1980s as a miraculous anti-aging ingredient. They became part of acne treatment protocols and are now widely used in dermatology and cosmetics to exfoliate, hydrate, and renew the skin's surface.
HOW TO INTRODUCE ACIDS INTO YOUR ROUTINE?
You can use acids daily as toners, essences, serums, or occasionally as exfoliating masks. A low-concentration acid toner is often the first product you introduce into your evening routine, allowing your skin to adjust. For sensitive skin, use it every other night. Once your skin adapts, you can move on to higher concentrations in serums or chemical peels as masks.
WHICH ACID FOR YOUR SKIN TYPE?
Each of these acids provides gentle exfoliation, and the size of their molecules affects their ability to penetrate the skin, as well as the potential for irritation.
Often, products combine various acids to synergistically address skin concerns, making these combinations more effective than mixing individual acids yourself.
AHAs (Alpha-Hydroxy Acids) – For Dry and Normal Skin
Glycolic, citric, mandelic, and lactic acids are water-soluble and best suited for normal and dry skin types. Glycolic acid has the smallest molecules, penetrates the skin easily, and has a higher potential for irritation. Lactic and mandelic acids have larger molecules and are gentler, making them more suitable for sensitive but not damaged or irritated skin. AHAs improve skin moisture and elasticity by speeding up the renewal of skin cells, helping to reduce wrinkles and hyperpigmentation.
BHAs (Beta-Hydroxy Acids) – For Oily Skin
Salicylic acid is the only well-researched BHA used in cosmetics. It is oil-soluble, making it ideal for cleansing pores and exfoliating oily skin. It also has important antibacterial and anti-inflammatory properties, making it valuable for acne-prone skin.
PHAs (Poly-Hydroxy Acids) – For Sensitive Skin
PHAs have large molecules that work on the skin's surface with a low irritation potential, so they are recommended for people with sensitive skin, rosacea, or dermatitis. The most well-known PHAs are gluconolactone and lactobionic acid.
…And Other Important Acids
Some well-known acids do not fall into these categories but are common in cosmetics, particularly for their antioxidant properties.
Azelaic acid is recommended for its calming and antioxidant effects, especially for sensitive skin and those with rosacea, acne, or hyperpigmentation.
Kojic acid works on hyperpigmentation issues by inhibiting melanin production.
Lotion, Cream, Serum, or Peel?
Acids can be used in two ways: as part of your daily routine or as an occasional peel.
It's recommended to start with a toner or lotion that has a well-balanced combination of acids, which should be the first step after cleansing.
Toner
The Ordinary 7% Glycolic Acid – Start using it in the evening, applying with a cotton pad to clean skin, and wait for it to dry before applying the rest of your skincare. The toner contains soothing and hydrating ingredients like aloe vera and ginseng.
Glycolic Acid Pads
MALIN+GOETZ Resurfacing Glycolic Pads – Pads soaked in a 10% glycolic acid solution are intended for evening exfoliation, replacing a toner or serum.
Essence
Royal Fern Phytoactive Skin Perfecting Essence – An effective combination of PHA (gluconolactone) and an AHA complex to stimulate skin renewal, even out texture and tone, and provide an instant glow. The product also contains a powerful antioxidant and anti-inflammatory "Royal Fern" complex.
Serum
Darphin Youth Resurfacing Peel – Combines lactobionic (PHA) and salicylic (BHA) acids for an effect similar to glycolic acid but without the irritation. Apply every evening before your other skincare products.
Esthederm Intensive AHA Peel Concentrated Serum – Contains alpha and beta hydroxy acids for exfoliation. The serum features a 12% complex of lactic, citric, and salicylic acids, plus glycolic acid with a gradual-release mechanism for extended action and reduced skin reactions.
Peel
The Ordinary AHA 30% + BHA 2% Peeling Solution – This popular product contains 30% AHAs (glycolic, lactic, and tartaric acids) and 2% salicylic acid for a strong deep peel. Use it cautiously, only if your skin is already accustomed to acids, and no more than once a week.
A patch test is recommended on the inner arm before applying it to your face. It’s ideal for improving skin texture prone to blemishes and as an anti-aging peel for smoothing wrinkles. It should not be used if you have any skin conditions or irritated, sensitive skin.
HOW TO COMBINE ACIDS WITH OTHER INGREDIENTS?
Use only one acid-based product in your daily routine. Choose one acid or a product with a combination of acids designed for your skin's condition.
Avoid using acids in the same routine as retinoids and vitamin C.
Niacinamide can be combined with salicylic acid, as these two ingredients often appear together in products for oily, acne-prone skin. However, niacinamide should not be mixed with glycolic acid.
SPF is essential every day, but even more so when using acids, as they reduce your skin's resistance to the sun. Some acid and sun combinations (especially glycolic acid) can cause burns or hyperpigmentation.
Ideally, use acid products in the evening and hydrating, protective creams during the day.
