5 Acids You Should Consider Adding to your Skincare Routine

What is an ‘acid’? Let’s take you back – just briefly – to your GCSE or A-level chemistry class…

The pH scale is a measure of acidity or alkalinity of a substance, on a scale of zero to fourteen, with zero being the most acidic, fourteen being the most alkaline, and seven being neutral. When things of different pH levels come into contact with each other, chemical reactions occur. Skin is somewhat acidic, with a pH between four and six, so different products applied to your skin can have an effect on its pH and, in turn, have a potentially beneficial or harmful effect on your skin.

Your skin is protected by a surface coating called the ‘acid mantle’ made up of sebum (oil produced by the oil-producing sebocytes in the skin) and your own sweat. This protects your skin from environmental damage and dehydration and stops the growth of bacteria. Both very acidic and very alkaline substances can be harmful to the skin, making it more susceptible to irritation and infection as well as skin diseases such as acne. For example, soaps tend to have an alkaline pH and this can remove the acid mantle from your skin, worsening dry skin or skin conditions such as eczema.

But some acids can potentially be very good for skin, though they can all cause a certain level of irritation, especially when you first start to use them. Acid-based products are meant to target ‘abnormal keratinisation’ – keratinocytes are skin cells and normally they shed from the skin in a regular cycle. If this shedding doesn’t happen as planned, the cells stay on the skin, causing problems like blocking pores (these are seen as white or blackheads – known medically as ‘comedones’) but can also contribute to the dry, rough appearance of ageing skin.

Here are the top five acids you should consider adding to your skincare regime, depending on what specific problem you want to tackle, and how best to use them:

Alpha-Hydroxy Acids

Alpha-hydroxy acids (AHAs) help shed the top layer of the skin known as the stratum corneum, giving your skin a ‘smoother’ appearance. They are also known to increase skin thickness by increasing collagen synthesis in the dermis and reducing the melanin (pigment) in the epidermis, improving the appearance of melasma or post-inflammatory hyperpigmentation – the dark mark that you are left with after acne spots resolve. Glycolic acid peels at five to ten percent are the most common AHA peel and work by helping the top layers of the skin shed and opening up clogged pores.

Target: Anti-ageing, hyperpigmentation, mild to moderate acne, comedones.
Usage: Weekly glycolic acid peel (five to ten percent), daily ten percent glycolic acid cream.

Salicyclic Acid

Salicylic acid (SA) is known to have comedolytic (comedone-clearing) properties as well as being moderately effective in the treatment of acne. A two percent  SA cleanser showed a significant improvement in moderate acne in a group of 30 patients after just two weeks of daily use. A 20 percent SA peel is also an effective and safe once-a-week treatment to help clear spots, even when combined with powerful acne-fighting prescription drugs like Roaccutane. Definitely patch test this type of peel behind your ear or on your neck before trying it out on your whole face just to make sure it doesn’t cause a lot of redness or irritation!

Target: Comedones, mild to moderate acne, as an adjunct to Roaccutane to improve efficacy.
Usage: Two percent SA face cleanser, 20 percent SA weekly or bi-weekly peel.

Lipo-Hydroxy Acid

You might not have heard of lipo-hydroxy acid (LHA) but it is worth knowing about! LHA is a derivative of SA and has been shown to be as effective a five percent benzoyl peroxide (BPO) applied twice daily as a lotion to reduce the number of spots in patients with acne. LHA peels also seem to be slightly more effective than SA peels (six weeks in two-week intervals over 12 weeks) in reducing comedones (blackheads and whiteheads).

Target: Comedones, mild to moderate acne.
Usage: Use in lotion form twice daily, and as a peel every two weeks.

Linoleic Acid

A deficiency in linoleic acid (LA) is associated with problems creating and shedding the lining of the top part of the hair follicle that attaches the oil gland to the outermost layer of the skin. This can lead to comedone formation and visibly enlarged pores. A double-blind, randomised, placebo-controlled crossover study examined the effect of 2.5 percent LA gel on comedones and enlarged pores. Biopsies of the skin after treatment showed a significant reduction in the size of the follicles and the number of comedones.

Target: mild acne, comedones, enlarged pores.
Usage: 2.5 percent gel formulation applied twice daily.

Lauric Acid

Lauric acid is a medium-chain fatty acid that has antimicrobial activity against P. Acnes, the bacteria believed to be a culprit in causing acne in the first place. Studies have shown that it has a powerful bacteria-killing effect at the skin surface at a concentration 15 times lower than that of benzoyl peroxide (BPO). This is good news for people who find BPO very irritating to their skin. This acid is still being studied so you probably won’t find a product that contains it yet, but watch this space and be ready when it hits the shelves!

Target: Mild to moderate acne, potentially to replace more irritating treatments like BPO.
Usage: Most likely in a gel formulation but not yet available – watch this space!

The most important thing to remember is to be patient. Your skin needs time to heal and the products need time to work. There is no cream that will give you an overnight ‘cure’ – like most things in life, consistency and patience pay off. So when you are trying out a new product or treatment – whether it’s from Boots or a prescription from your dermatologist, don’t throw in the towel if you don’t see results in a week. Try different acids for at least three months and then decide if it’s worth keeping them in your skincare arsenal. And don’t forget to protect your skin from the sun every morning with a mineral-based SPF 30 sunscreen.

Dr Natalia Spierings
Dr Natalia Spierings
Dr Spierings is a leading consultant dermatologist in the UK with a medical degree from St George's University of London. She has a decade's worth of experience treating acne and anti-ageing, and is dedicated to providing safe, efficient and patient-centred care at every opportunity.
Originally published March 21 2018, updated June 27 2019

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