Everything you need to know about salicylic acid
Salicylic acid is a common skincare ingredient which can be found in both in-salon treatments and at-home products and is typically used to treat and prevent oily skin, breakouts, blackheads and mild acne.
In the second instalment of our acids series, we speak to the skincare experts to find out the best ways to use salicylic acid.
What is salicylic acid and how does it work?
Salicylic acid is a beta hydroxy acid, or BHA – meaning it is only one carbon atom less than the more populous alpha hydroxy acids (AHAs) like glycolic acid, lactic acid and mandelic acid.
Like both of those acids, salicylic also has a natural origin. “Salicylic acid is a derivative of willow bark and belongs to a group of naturally made, plant-derived chemicals called salicylates,” explains Be Loasby-Smith, national educator for Xpert Professional which distributes professional skincare brand Dibi Milano.
Salicylic acid’s structure means it’s more oil soluble than AHAs, which are water soluble, making it effective on oily skin and resulting skin concerns.
“This acid mixes with the lipids and sebum on the skin’s surface, disrupting cellular junctions. This action helps slough off dead skin cells and remove the contents of clogged pores – decreasing the appearance of pore size and improving skin health,” says Victoria Evans, education manager at Dermalogica UK.
Evans says that salicylic acid is something of a multitasker: “It has a keratolytic effect, softening and loosening the bonds that hold keratinocytes in place; a comedolytic effect by dissolving follicular impactions; and an anti-inflammatory action.”
This means it’s great for clearing out blackheads and whiteheads in the skin, as well as bringing down redness when breakouts do occur. Salicylic acid can also prevent future breakouts because it decreases the spread of Propionibacterium, an acne-causing bacteria.
How should salicylic acid be used?
In salons or clinics, it can be used in a number of different treatment stages. Rebecca Jones, trainer and ambassador for Noon Aesthetics, explains, “Salicylic acid works to de-oil the skin and remove surface build up, so it is a great prep choice before extractions, lymphatic massage and oxygen infusion.”
It’s also a great ingredient to use alongside LED light therapy treatments “due to combination working effectively at combating breakouts”, according to maskology+ national trainer Deborah Carrington.
Salicylic acid can also be incorporated into a facial or chemical peel treatment in clinic, and is often implemented as a peeling agent within a chemical peel treatment.
Outside of the salon, it can be used by clients at home in concentrations of 2% or less. The ingredient is widely available in products such as cleansers, exfoliants, serums, spot treatments and masques.
Although salicylic acid is safe for clients to use at home in this percentage, they do need to be careful not to overdo it.
“Caution must be taken to not dry out the skin too much,” explains Loasby-Smith. “Using such products sparingly and following up with hydrators such as a hyaluronic acid serum and ceramide-rich moisturisers will make sure the skin is not stripped of all its moisture.”
What can you use with salicylic acid?
As mentioned, hyaluronic acid is a great pairing – it helps boost moisture and restore the skin’s barrier – but there are a few other ingredients which will help to either soothe the aftereffects of salicylic acid use or increase its efficacy in treating certain skin concerns.
“Water-soluble ingredients like niacinamide will make a fantastic pairing with salicylic acid because it will complement the oil-soluble acid beautifully, working on locking in moisture all day and avoiding skin dryness, redness or vulnerability,” explains Loasby-Smith
Evans says that “other anti-acne ingredients and other AHAs to complement the skin-clearing and anti-inflammatory benefits” also pair well with salicylic acid, although care should be taken not to overload the skin with actives – clients can work them into their routines at different times of the day.
If salicylic acid is being used to treat existing mild acne issues and breakouts, Jones adds that “skin-brightening ingredients like azelaic acid will reduce the chances of post-inflammatory hyperpigmentation” resulting from these skin concerns.
What reacts badly with salicylic acid?
Since salicylic acid is an active ingredient, caution should be taken when layering products in order to avoid irritation and sensitivity.
Although retinoids and salicylic acid are both well known for their acne-fighting abilities, the two together are a combination which should be avoided – especially with high-strength retinoids.
Dr Ros Jabar, owner of Ros Medics Aesthetics Clinic in Cardiff, says, “Using any topical salicylates should be avoided with medications that are already being prescribed for acne such as isotretinoin, tretinoin or adapalene because this would compound the effect.”
Sadly, brightening hero vitamin C is often a no-go too. Vitamin C is a notoriously unstable ingredient and combining it with salicylic acid can lessen its efficacy. “The pH of the skin may be thrown off by layering these products,” explains Jenna Unwin, founder of Million Dollar Facial.
Do you want to work salicylic acid into your skincare routine and avoid sensitisation? Find out how skin cycling works to prevent overprocessing the skin.
Are there any contraindications with salicylic acid?
Allergies are always a concern with skincare ingredients – some people can even be allergic or sensitive to something as seemingly innocuous as hyaluronic acid. This is also the case with salicylic acid, although identifying whether someone might be sensitive to this ingredient should be easy via a treatment consultation because of it’s relation to a common medication – aspirin.
Loasby-Smith explains, “Salicylic acid should not be used by anyone who has an allergy to aspirin. Aspirin is prepared by chemical synthesis from salicylic acid and should therefore be avoided by anyone with an aspirin allergy.”
She adds, “Salicylic acid should also be avoided during pregnancy. It has been characterised by the FDA as a ‘Class C’ drug, meaning that while no human studies on pregnant patients have been completed, animal studies have had implications on the foetus.”
People with eczema or sensitive skin should also exercise caution because the ingredient can increase dryness and irritation. If this is the case, “usage should be kept to either once a week or alternate days if you are sensitive,” adds Carrington.
Other medical conditions can also preclude the use of salicylic acid, emphasising the importance of pre-treatment consultations. Dr Jabar says, “Those that are diabetic or that have some porphyria diseases should not use this product.
“People that have any liver or kidney problems should also apply caution and avoid the use of salicylic acid, as well as those who are prone to cold sores or anyone that has a cold or flu or is immunosuppressed.”