Your Guide to the Most Common Acids in Skincare – When and How to Use Them?

Most people would agree that the word ‘acid’ can feel quite intimidating in skincare, especially when it’s something you put on your face. However, despite the name, most skincare acids are perfectly safe and gentle ingredients that can do great things for your skin. So, here’s a breakdown of the acids you’re most likely to come across:

Common Acids in Skincare

Salicylic Acid

Also known as BHA (Beta Hydroxy Acid), salicylic acid is oil-soluble, which means it has the ability to penetrate deep into your pores and dissolve any debris build up within them. It’s, therefore, seen as a blemish control product. 

• Best for: Combination to oily and acne-prone skin.
• What it does: Unclogs pores, reduces blackheads, calms inflammation, increases skin radiance. 
• When to use it: Concentrated BHA should be used two to three times a week to begin with, ideally in the evenings. A gentler salicylic acid serum can be used daily, morning and evening, before applying any other creams. 

Glycolic Acid

Similarly to salicylic acid, glycolic acid or AHA (Alpha Hydroxy Acid) is also a type of chemical exfoliant. However, instead of being oil-soluble it is water-soluble, working primarily on the skin’s surface while still targeting blemishes. 

• Best for: Dull, uneven skin tone and fine lines; suited to normal-to-oily skin.
• What it does: Exfoliates dead skin cells, smooths texture and encourages cell turnover.
• When to use it: Evenings only, as it increases sun sensitivity (always use an SPF the next morning).

Lactic Acid

Lactic acid is another type of AHA. However, it’s known as a gentler alternative to glycolic acid and is naturally derived from fermented dairy sugars, although it can also be produced synthetically. 

• Best for: Highly sensitive skin as well as dry or mature skin.
• What it does: Exfoliates, brightens, lightly hydrates.
• When to use it: Evenings, two to three times per week, pairing with SPF the following morning.

Hyaluronic Acid

Hyaluronic acid is one of the most powerful ingredients in moisturisers – it’s incredibly effective in drawing moisture into the deeper layers of the skin. Although our skin already produces it naturally, the levels start decreasing as the body ages. That’s where skincare products with HA come to your aid. 

• Best for: All skin types, including sensitive and dry skin.
• What it does: Holds up to 1,000 times its weight in water, plumping and hydrating the skin. 
• When to use it: Morning and evening, applied to damp skin before moisturiser. Though, in most cases, hyaluronic acid is already included in the moisturiser and doesn’t need to be applied separately. 

Azelaic Acid

Azelaic acid is a multitasking ingredient that is naturally produced by our skin but can also be derived from grains, such as wheat and barley. It’s highly-regarded by dermatologists for its powerful antibacterial and anti-inflammatory properties, while being well-tolerated by most skin types. 

• Best for: Inflamed skin, rosacea, hyperpigmentation and post-acne marks.
• What it does: Reduces redness and inflammation, fades dark spots, kills acne-causing bacteria and gently unclogs pores.
• When to use it: Morning or evening, starting with 2-3 times a week to build tolerance. It’s also one of the few acids considered safe to use during pregnancy (always check with your GP first). 

Ascorbic Acid

Ascorbic acid is the purest and most potent form of vitamin C in skincare. It has lots of incredible benefits, including antioxidant properties and boosting collagen production, though it requires careful formulation to remain stable (it’s highly prone to oxidation when exposed to light and air).

• Best for: Dull skin and dark spots. Also those seeking antioxidant protection.
• What it does: Brightens the complexion, fades hyperpigmentation, helps in firming the skin and protects against free radical damage.
• When to use it: Every morning, before your daily moisturiser and SPF.

As you can see, the world of skincare acids becomes a lot less intimidating once you understand what each one actually does. It’s best to start with one acid at the time, introducing it slowly, and always consult your dermatologist if you have any skin conditions.