Our Guide to Acids.

August 02, 2020 Sabina Jasinski

AHA:

Alpha hydroxy acids main function on the skin is exfoliation. AHAs exfoliate on the top layer of the skin, removing the “glue” that binds dead skin cells together causing them to build up and trap dirt and debris.

Most common types of AHAs:

Glycolic acid: made from sugar cane.
Lactic acid: derived from milk.
Malic acid: derived from apples and pears.
Citric acid: derived from oranges and lemons.
Tartaric acid: derived from grapes.

How do they work? AHAs cause the top layer of dead skin cells to get “unglued” making room for regrowth of fresh cells. This also gives the skin a smoother feel as it is cleared of debris and old, dead skin cells.

AHAs are water soluble - meaning that they are mostly active on the very top of the skin.

AHAs have been widely shown to improve skin texture, minimise fine lines and wrinkles, repair photo-damaged skin and decrease pigmentation.

Side effects: AHAs cause sun sensitivity and can be irritating to certain skin types. Glycolic acid has a smaller molecular size and can be more irritating to certain skin types due to its penetration depth. Lactic acid has a larger molecular structure and is often found in exfoliating products for sensitive skin types.

Whenever you are using an exfoliating ingredient - SPF is key. Undoing sun damage with AHAs is great but the upkeep with an SPF is more important in order to stop further damage, pigmentation and potential skin cancers.

Choosing a product with AHA: There is a vast choice of AHAs in many different skincare products such as cleansers, masks, serums, toners… you name it. We recommend choosing 1 product in your skin care routine that has an AHA content in order to minimise irritation and over usage.

The safest products with AHAs are exfoliating masks as you can rinse off the product after receiving its benefits. If you are used to AHAs, going for a toner containing AHA in the evening is also a good option.

Don’t forget that cosmetic manufacturers are not required to state the concentration of ingredients on their labels, so with AHAs it is important that you look for AHAs listed within the first 4-5 ingredients. In this way, you know you are getting an effective concentration as going lower may not do anything at all and you are just wasting your money on a false-claim product.

Best Suited for:

Photo-damaged skin
Thick skin
Wrinkles and lines
Skin not prone to break outs
Normal- dry skin types (AHA enhances moisture factor of skin)

PHA - Polyhydroxy acids:

Similar to AHAs, PHAs have a much larger molecular structure which doesn’t let them penetrate as deep and therefore are much less irritating to certain skin types. They also do not sensitise the skin to UV rays.

Most common types of PHAs:

Glycolactone
Galactose
Lactobionic acid

How do they work? PHAs are exfoliants that remove dead skin cells for the surface of the skin. They also fight glycation - this is when a digested sugar molecule attaches itself to collagen within the skin and starts to weaken it and the elastin. PHAs are high in antioxidant activity and also stimulate epidermal growth and repair.

Side effects: Any exfoliating ingredient can cause irritation - remember to gradually add any new skincare ingredient to your routine, even when said to be ”for sensitive skin”. Always wear sun-protection, even when an ingredient claims “not to cause sun sensitivity”.

Choosing a product with PHA: Moisturisers and toners with PHA are a great way to incorporate the ingredient as they usually contain other soothing and moisturising ingredients .

Best suited for:

Dry, itchy skin
Sensitive skin with eczema, atopic rosacea

BHA - Salicylic Acid:

Compared to AHA, BHA sinks in deeper into the skin as it is a fat soluble molecule. Fat solubility causes it to reaches the oil in clogged pores and dissolves it along with excess build up. BHA also makes the skin less photo-sensitive as it is shown to absorb UV rays.

How does it work? BHA is an exfoliant that penetrates into pores containing oily sebum and exfoliate dead skin cells within the pores. BHA is a great treatment for people with oily skin or suffering from white heads, blackheads and overall congestion of the skin.

Side effects: As with any skincare ingredient, irritation can occur. BHA is shown to be less irritating than AHAs. When adding a new ingredient to your routine - do it gradually, once a week working your way up to what your skin can tolerate. Salicylic acid is also known to have anti-inflammatory properties because it its derived from acetylsalicylic acid (aspirin). Due to the fact that BHA absorbs UV rays - this does not mean that you can skip the SPF. SPF should always be applied and especially when exposing the skin to exfoliating ingredients. Other rare but still potential side effects include redness, burning, and scarring. Darker skin types have a higher risk of scaring and developing pigment changes with BHA.

Choosing a product with BHA: Cleansers containing BHA that are left on for 2 minutes have great exfoliating properties with minimal irritation because they are rinsed off. Exfoliating toners are a great way to target specific areas on the skin that may suffer from breakouts, whiteheads and/or blackheads.

In Korean beauty products it is very common to find an ingredient called Betaine Salicylate. It is a combination of salicylic acid and betaine which gives the skin exfoliation and moisture. South Korean formulations are only allowed to contain very small amounts of salicylic acid and therefore betaine salicylate acts as a replacement.

Skincare manufacturers can list BHA in the middle or lower part of ingredients lists as it is effective in lower concentrations (compared with AHAs that work in a higher concentration).

Avoid buying SPF and BHA in one - the ingredients destabilise each other and can cause irritation, unwanted effects and a weaker SPF. A general rule is to always use an SPF last and keep it separate from your other skincare.

Best Suited for:

Acne, whiteheads, blackheads
Congested skin
Oily skin
Teenage skin

LHA - Lipo hydroxy acid:

Derived from BHA, it has a similar effect as BHA but a much slower rate of penetration making this an ideal exfoliator for people with extreme sensitivity suffering from acne and congested skin.

It has a higher molecular weight and a stronger lipophilic effect meaning that it dissolves fat, oils and lipids such in pores that may cause breakouts and acne.

How do they work? LHA is a fat soluble exfoliant that dissolves oil. It targets sebum rich sebaceous glands and prevents acne and spots. LHA exfoliation also reduces blockages of dead skin cells within pores and has anti-inflammatory, anti fungal and antibacterial properties. LHA has also been shown to aid the penetration of other skincare ingredients, boosting their effectiveness. LHA has a slow acting time meaning that it can take longer to see results but it is less sensitising to the skin in this way.

Side effects: Even though this is one of the gentler exfoliating acids, some people can over-exfoliate which in turn can cause irritation. Always use an SPF when using exfoliators.

Choosing a product. Spot correctors, area specific products that target the T zone and chin, nose that can get easily congested. As a mask, leave on treatment.

Best suited for:

Very sensitive skin with acne and breakouts
Acne, oily skin
Beginners to acids

Azelaic Acid:

This is a gentle exfoliating acid that can be left on the skin with minimal irritation and studies have shown it to prevent and reduce breakouts, fade red marks and pigmentation, smooth out complexion and reduce overall skin sensitivity. It is a dicarboxylic acid that declogs pores and fights inflammation.

How does it work? As a mild, leave on exfoliant its main abilities are to unclog pores and refine skin texture. It slows down the progression of emerging skin conditions which means that it “tells the skin how to behave”. This in turn, decreases swelling, kills acne causing bacteria and decreases keratin production. It takes longer to “work” than your traditional exfoliating acids and therefore results are visible after prolonged use. It is also shown to lighten hyperpigmentation.

Side effects: As with any acid or new ingredient exposed to your skin it can cause a burning sensation, dryness and peeling (depending on concentration used in a formulation). Always remember to use SPF, even though it minimises skin sensitivity, it never protects you from UV radiation.

Choosing a product: Azelaic acid is still relatively new in the cosmetic market. There are prescription ointments and oral tablets but there are great serums emerging that can be incorporated into any skincare routine.

Best suited for:

Pigmentation
Rosacea
Acne and oily skin
Uneven skin tone

Hyaluronic Acid:

This famous acid has been around for a while and has risen in popularity due to its amazing moisture holding properties. It is not an exfoliant, it is a humectant - it attracts moisture and binds it to the skin. Hyaluronic acid exists naturally in our skin and plays a big part in our skins overall health. High molecular hyaluronic acid hydrates the skin and skin barrier. Low molecular hyaluronic acid hydrates the skin on a slightly deeper level but still works mainly on the top layer of the skin. Low molecular hyaluronic acid has shown to help the skin repair by increasing its self defence.

How does it work? Hyaluronic acid acts like a sponge. It attracts moisture and binds it to the skin and by doing so boosts hydration levels. As hydration is increased, skin cells are happier and can regenerate and repair themselves.

Side effects: Side effects are rare, but like any ingredient - it can cause irritation in some skin. Ultra low molecular hyaluronic acid can cause irritation in some. Another point to remember is that when using hyaluronic acid, it is important to seal it in with a moisturiser as hyaluronic acid alone can evaporate from the skin, drawing out moisture leaving your skin dry and dehydrated.

Choosing a product: Serums are extremely popular and effective. Toners can also add a hydration boost but remember to lock it in with a moisturiser after. Moisturisers containing hyaluronic acid are also available but look for gentle ingredients that are non irritating and do not contain alcohol as this can weaken the hyaluronic acid and cause it to evaporate.

Sodium hyaluronate is a popular ingredient found in many skincare products claiming they contain hyaluronic acid. Sodium hyaluronate is sodium form of hyaluronic acid. They are very similar to each other with the same skin hydrating effects. Sodium hyaluronate is said to be slightly more stable and cheaper for manufacturers so that is why it is seen more on ingredients lists.

Best suited for:

All skin types
Dry, dehydrated
Mature
Sun damaged
After being in the sun

Kojic Acid:

Made from different types of fungi and a byproduct of fermented foods from the east, Kojic acid is an tyorsine inhibitor - meaning that it block the amino acid needed to create melanin. It has a lightning effect on the skin and is great for minimising scarring.

How does it work: Tyrosine is an amino acid that creates melanin and kojic acid blocks this synthesis that overtime removes unwanted scarring and brown spots.

Side effects: Kojic acid can cause skin to be more prone to sunburns. It can also cause contact dermatitis in sensitive skin types. Do not use on damaged or broken skin.

Choosing a product: Kojic acid needs to be “left on the skin” to reach its maximum potential so choosing products such as serums, moisturisers and masks are the best way to go. Always follow with and SPF.

Best suited for:

Pigmentation
Post acne scarring
Humid climates

Ferulic Acid:

A plant-based antioxidant that has fantastic free-radical fighting effects. It boosts effectiveness of other antioxidants such as vitamin A, C and E and is known to stabilise vitamin C. It also helps the skin protect itself from UV rays and reduces inflammation and sagging skin.

How does it work: Ferulic acid neutralises free radical damage that leads to ageing of the skin and acts as a shield for free radical protection. By doing this, over time it decreases signs of ageing such as fine lines, wrinkles and pigmentation.

Side effects: Certain antioxidants can be “too active” for certain skin types. Remember that any ingredient can cause irritation and ferulic acid has this capability when mixed with fragrance or some preservatives. Remember to add new ingredients into your routine gradually to minimise chances of a reaction. Always use SPF, even though ferulic acid protects against UV rays, it is by no means a sunblock.

Choosing a product: Serums in opaque, dark bottles are the best choice as they have the smaller chance of contamination by heat and light. Look for formulations with minimal ingredients to ensure stability and purity. Use once a day on clean skin followed by a gentle moisturiser. Do not mix ferulic acid with AHA or BHA as this alters the pH and lessens the effectiveness of the antioxidant.

Best suited for:

All skin types
Mature skin
Photodamage and pigmentation

Tranexamic Acid:

A derivative of the amino acid lysine, was originally used in medical practices to curb bleeding. It found its way into the skincare industry as it has powerful effects of fading pigmentation, brown spots, keloid scarring, melasma and pregnancy melasma. It aslo decreases sun sensitivity.

How does it work? Tranexamic acid has powerful anti-inflammatory action where it inhibits tyrosinase synthesis in melanocites. It also blocks the transfer of melanocytes to keratinytes in the top layer of the skin. As melasma is a type of inflammation of the skin, tranexamic acid drastically slows this process.

Equally it helps the skin restore and repair the skin barrier.

Side effects: No documented side effects have been seen yet as this is a relatively new ingredient in the cosmetics industry however as always - any ingredient can cause irritation so add with caution and care to your routine.

Choosing a product: Serums tend to have the highest potency and can be used as area specific-treatments on the skin. Use once every other day to respect skin tolerance. Tranexamic acid can be combined with retinol, vitamin C, kojic acid to maximise its brightening effect.

Best suited for: