The sum total

Skincare ingredients are tricky to decipher without throwing maths into the equation. So, what exactly do percentages in our serums and creams really mean? And how much do they matter?

just a few years ago, terms like retinol and glycolic acid might have prompted looks of bewilderment. Nowadays, however, thanks to innovative brands honing in on single-ingredient formulations, they’re part of our everyday beauty vocabulary. Yet with so many different products to choose from, problematic percentages have begun to cause confusion. Logically, you’d be forgiven for thinking that a 20% vitamin C serum is more potent and superior to one of 10%, but that’s not always the case. ‘More’ of an active ingredient doesn’t necessarily mean ‘better’. Here we break down the real value of percentages in skincare, so your beauty routine adds up…

DO THE MATHS GLYCOLIC ACID

Glycolic acid is an alpha hydroxy acid (AHA) and is the holy grail for topical exfoliation. Formulations containing between 3% and 5% hit the sweet spot for everyday use. But there’s a caveat. The ph level plays a vital role. A high ph level acts as a buffer to reduce any potential irritation, but it also dilutes the acid. ‘If you have a 5% glycolic with a ph level that’s high, it weakens the acid, lowering it to around 2%,’ explains Dan Isaacs, formulation and development director at Medik8. The ph levels won’t be on the ingredient list, so do your homework and check the brand website. ‘Ideally, you want a ph of 3 to 4. This allows the acid to work, but won’t aggravate the skin,’ adds Isaacs. You can move on to a higher percentage of glycolic once your tolerance levels adjust, but we’re talking months of use here, not weeks. At that point, try The Inkey List Glycolic Acid Toner, £6.99, which contains 10% and gnaws away at old skin cells to reveal your most luminous complexion to date.

NIACINAMIDE

Known as vitamin B3, niacinamide’s prowess lies in its ability to increase the fatty content of the skin cells and aid water retention. This enhances barrier function of the epidermis, making it popular among acne sufferers, as it protects against bacterial attack. Always pick a product that declares the amount of niacinamide. ‘If the percentage of an active is not mentioned, it is extremely likely that inconsequential amounts are used,’ reveals Deciem chief innovations officer, Prudvi Kaka. As little as 4% is proven to be effective on blemishes and brightening skin tone, but formulations go as high as 10%, such as The Ordinary Niacinamide 10% + Zinc 1%, £5. Finally, niacinamide can weaken the potency of vitamin C, so alternate your application.

VITAMIN C

The stability of vitamin C within a formula is much more important than the percentage. In a nutshell, if vitamin C had a star sign, it would be Gemini, because it’s completely two-sided. L-ascorbic acid is the strongest form of vitamin C and is a powerhouse when it comes to dusting off sun damage and fine lines. Yet, it’s also the weakest form of vitamin C, because once it comes into contact with air and heat, it oxidises, rendering it useless. Therefore, a stable 5% vitamin C serum will be more effective than a 25% serum that isn’t stable.

So, how do you look for stable formulations? Packaging is key. Alumier MD Everactive C&E, £149, contains 15% L-ascorbic acid, which is stored in a separate cap above the serum. You only mix the concentrated vitamin C powder with the rest of the serum as and when you want to use it, ensuring its efficacy. Stable formulations won’t contain water either. Try Allies of Skin Vitamin C 35% Collagen Rebuilding Serum, £108, which is totally waterless so has zero chance of going off.

RETINOIDS

These are various forms of vitamin A. They are mightily effective at ironing out wrinkles and obliterating breakouts because they rev up skin cell turnover at lightning speed. There are three levels of retinoids: pure retinoic acid, which is the strongest and prescription-only; retinol, which is sold over the counter and is weaker and less irritating than the pure acid, and finally retinyl palmitate, which is the gentlest of the bunch. ‘You need to understand the type of retinoid before you look at the percentage.

A 10% retinyl palmitate serum is weaker than a 5% retinol serum,’ explains Dan Isaacs. As a rule of thumb, it pays to build up your retinol use. If you’re really sensitive, start with a product that has a low percentage of retinyl palmitate before moving onto retinol.

If you’re OK after two weeks, increase it to every other day until you can apply it neat on to the skin daily. Apply moisturiser afterwards to avoid dryness. Start with Sunday Riley A+ High-dose Retinoid Serum, £70. It’s powered by a 6.5% blend of retinol botanical extracts, yet it’s weaker than Medik8 r-retinoate Intense, £210, which is formulated with 0.6% retinol.

MANDELIC ACID

Derived from bitter almonds, mandelic is the newest exfoliating acid on the block. It differs from glycolic because its molecule size is twice as big, so it takes longer to penetrate the skin and therefore negates any irritation. It’s perfect for those who have never tried acids before, but don’t be fooled by its softly-softly approach – it’s been championed by cystic acne sufferers for years. It’s also promising for those with darker skin tones because, unlike other acids, it doesn’t cause post-inflammatory hyperpigmentation. First-timers should seek out Wishtrend 5% Mandelic Acid Skin Prep Water, £32.20. It can be used daily and is strong enough to boost radiance. To banish breakouts, you’ll need to up the ante to 10%. However, Dr Sarah Shah explains that it can be counterproductive to go any higher. ‘You’re better off using a lower strength 5% glycolic,’ she says. Garden of Wisdom 10% Mandelic Acid Serum, £9, is a long-term clarifier that blitzes dirt from pores. Apply two to three times a week, post-cleansing, and leave on for 20 minutes before moisturising to allow for penetration.