Skincare acids have fast become staples in our beauty regimes because of their proven ability to resurface the skin.

Bazaar UK / Florian Sommet

They work as chemical exfoliants, either lifting off the build-up of dead cells on the skin’s surface to reveal a brighter, smoother complexion (by use of alpha hydroxyl acid, AHA), or by penetrating into the pores to shift buildup and help clear breakouts (by use of beta hydroxyl acid, BHA).

However, without picking the right formula for your skin type – or by using them incorrectly – they can have the opposite effect to their primary intentions.

Michaella Bolder, skincare expert and celebrity facialist, says that in our pursuit for the ‘perfect’ skin, some of us have begun to mistakenly misuse acids.

“Overusing AHAs can leave the skin red raw, with possible burns, dryness and most certainly photosensitivity introducing premature ageing, thinning of the skin, risk of pigmentation – and, ultimately a confused complexion,” she warns.

Bolder says the acids used in skincare in their natural forms aren’t necessarily the causes of these issues, but rather it’s the formulations of at-home peeling products and daily exfoliators, plus add-on ingredients, that can overstimulate our skin.

“To avoid unsafe products, it’s essential that you take advice from an expert. Visit your facialist, a dermatologist, or do your research online,” she advises.

Once you’ve found the right product containing AHAs for you, “do not overuse your acid-based product,” she adds. “Once every other day is plenty unless you are on a programme with an expert that says otherwise.” However, it is safe to use BHAs (of which there is only one, salicylic acid), daily.

Remember, too, to be mindful of the other active ingredients (such as retinols and antioxidants) in your skincare line-up. “Too many highly active ingredients can also result in an imbalance within the skin, causing irritation and breakouts.”

As a rule of thumb, she says that on the days you choose to include AHAs in your routine, try to then avoid products containing vitamin C and retinol immediately after, allowing your skin to work with a single active ingredient at a time, therefore reducing the risk of overstimulation causing adverse reactions. “It’s also important not to mix your AHAs, this can cause immediate irritation and very unhappy skin!”

To work out the safest way to use acids in your skincare regime, Bolder gave us a guide to usage per age group and skin type. Take note:

Using acids in your 20s

“If you’re under 20 years’ old, you most certainly should not be using any skincare acids unless prescribed by your GP or dermatologist.

“In your early 20s, I’d recommend introducing a glycolic acid 5% (if you have normal / combination / dry / dehydrated skin) or salicylic acid 0.5% (for acne-prone / oily / combination skin), three-four times weekly unless advised otherwise. (Avoid use on broken or inflamed skin.)”

Using acids if you’re aged 25-35

“By this point, most skin types can tolerate a glycolic acid 10%, but sensitive skin should always perform a patch test before applying all over. For dry and dehydrated skins, lactic acid has a gentler, slightly more hydrating action. Use around four times a week.

“Salicylic acid 0.5% or 2% is always best for acne sufferers and oily skin types as this mild ingredient effectively regulates your sebum production while the antibacterial properties work to eliminate bacteria on the surface of the skin. In my opinion, it is always best when built into a cleanser and is safe to use daily at this stage.

“These options will help speed up your cell turn over, even-out your skin texture and tone, plus reduce over-productive sebum glands clogging up your pores.”

Using acids if you’re aged 35-45

“During this time, the visible ageing process is setting in, but this isn’t a call to ramp up the use of acids, you just simply need to hone your daily regime and continue with your acid usage as above.”

Using acids if you’re aged 45+

“If you have been using acids carefully over the past few years you will have built up a tolerance, meaning your skin can stand stronger acids on a more regular basis.

“If you’re happy using glycolic acid, try a 10% formula for daily use, or a 30% once or twice a week. For those favouring lactic acid, try a 10% formula every other day.

“If you still have oily skin, up your salicylic based cleanser to twice a day, followed by the use of a 10% glycolic acid toner every other day.

“Following each and every acids-based product it is imperative that you use a broad-spectrum SPF 30/50 daily, even in the winter months.”

From: Harper’s BAZAAR UK