Acids for the Skin

Skin is somewhat acidic, with a pH between 4 and 6, 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 don’t stop reading just yet.

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 per plan, 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 aging skin. Here are the top 6 acids you could consider adding to your skincare regime, depending on what specific problem you want to tackle and your skin type, and how best to use them.


Alpha-hydroxy acids (AHAs) help shed the top layer of the skin known as the stratum corneum, therefore giving your skin a ‘smoother’ appearance, but they are also known to increase skin thickness by increasing collagen synthesis in the dermis and reducing the melanin (pigment) in the epidermis, therefore improving the appearance of melasma or post-inflammatory hyperpigmentation – the dark marks that you are left with after acne spots resolve. Glycolic acid peels at 5-10% are the most common AHA peel and work by helping the top layers of the skin shed and opening up comedones (clogged pores). A recent randomised, controlled, double blind, placebo-controlled study (the ‘gold standard’ in medical research) compared 10% glycolic acid cream monotherapy for mild acne with a placebo (a ‘dummy’ cream) and found a significant improvement in acne in the glycolic acid-treated group after 90 days compared to the placebo group.

  • TARGET: anti-aging, hyperpigmentation, mild to moderate acne, comedones

  • HOW TO USE: Weekly glycolic acid peel (5-10%), daily 10% glycolic acid cream


Salicylic acid (SA) is a beta-hydroxy acid and is known to have comedolytic (comedone-clearing) properties as well as being moderately effective in the treatment of acne. A 2% SA cleanser showed a significant improvement in moderate acne in a group of 30 patients after just two weeks of daily use. A 20% 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. One study found that in 60 patients treated with Roaccutane combined with a weekly 20% SA peel for active acne had a 93% reduction in spots compared to a 73% reduction in patients just receiving Roaccutane alone. 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

  • HOW TO USE: 2% SA face cleanser, 20% SA weekly or bi-weekly peel


You might not have heard of lipo-hydroxy acid (LHA) but it is worth knowing about it. LHA is a derivative of SA and has been shown to be as effective a 5% benzoyl peroxide (BPO) applied twice daily as a lotion in reducing the number of spots in patients with acne. LHA peels also seem to be slightly more effective than SA peels (6 weeks in 2-week intervals over 12 weeks) in reducing comedones (blackheads and whiteheads).  

  • TARGET: comedones, mild to moderate acne

  • HOW TO USE: in lotion form twice daily, as a peel every 2 weeks


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% 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

  • HOW TO USE: 2.5% gel formulation applied twice daily


Polyhydroxy acids (PHA) are the newest type of acid to appear on the market. They are very similar to alpha-hydroxy acids but the molecules are larger, making them theoretically less irritating to skin as they cannot penetrate as deeply as smaller molecules. PHAs are listed on ingredients as lactobionic acid or gluconolactone. These acids also have a humectant property, meaning they draw moisture into the top layers of the skin.

  • TARGET: mild acne, sensitive skin, dry skin

  • HOW TO USE: 4% gluconolactone as a facial cleanser or lotion


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 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

  • HOW TO USE: Most likely in a gel formulation but not yet available – watch this space!

But probably the most important thing to remember is: give it time. 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 you dermatologist – don’t throw in the towel if you don’t see results in a week. Give anything at least three months and then decide if it’s worth keeping it in your skincare arsenal. And don’t forget to protect your skin from the sun every morning with a mineral-based SPF 30 sunscreen.

Until Next Time,

Dr. Natalia Spierings