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The importance of Hydroxy Acids in Skincare

The importance of Hydroxy Acids in Skincare

Hydroxy Acids have become very popular in the last 25 years and are included in specific skin care products.  They are mainly derived from sugar cane, red wine, sour buttermilk, almonds, apples, grapes and citrus fruits. 

The group of Hydroxy Acids can be divided in 3 sub-categories:

  1. Alphahydroxy Acids (AHA): include Glycolic Acid (sugar cane), Mandelic Acid (almonds), Lactic Acid (sour buttermilk), Tartaric Acid (grapes), Malic Acid (apples) and Citric Acid (citrus fruits).  
  2. Betahydroxy Acids: are not that often used in skincare, except for Salicylic Acid (extracted from the bark of willow trees) which is used in some anti-ageing creams and acne treatments.
  3. Polyhydroxy Acids (PHA) are in fact Alphahydroxy Acids with multiple hydroxy groups on the same molecule. These additional hydroxy groups attract water, making PHA compounds more hydrating and moisturizing than conventional AHA’s.  PHA compounds have been found to be gentler and therefore mostly used in sensitive skin products.  Gluconolatone and Lactobionic Acid are the most common PHA’s.

Hydroxy Acids are basically used to exfoliate the skin.  This procedure has been known since more than 2000 years: Cleopatra, the last Pharaoh of Egypt, was not wrong filling her bath with sour donkey milk, now known to contain lactic acid, which resulted in a softer and smoother skin and a brighter appearance.  By the way: Cleopatra was not the raving beauty she has been portrayed as by various historians, but besides being intelligent, witty and charming she had a lustrous skin, hence the wrongful glorification of her beauty.

Fortunately today we do not have to purchase hundreds of litres of sour milk: since a German dermatologist described in 1882 the properties of a series of acids as chemical peeling agents, the cosmeceuticals industry has developed a range of products which, depending on their formulation, vehicle, acid type, pH and concentration, can provide a much wider range of treatments than only exfoliation.

To better understand the benefits of Hydroxy Acids in skin care products it is necessary to review briefly the structure of our skin and the processes taking place within it.

The skin is our principal organ of beauty, touch, pleasure and sensuality.  It is the largest organ of the human body accounting for about 14% of our total body weight and covering 1,2 to 1,9 square meter. 

The skin is composed of three main layers:


The epidermis is with its 1,0 mm the thinnest skin layer.  It is itself composed of 4 distinct layers of about 0,25 mm each.  The top outer layer, the “stratum corneum” (= Latin for “horned layer”), is made from dead, hard, tough cells that form the hard skin surface. 

The 3 lower layers produce millions of new cells every day.  These new cells start as soft cells and are gradually transformed into the hard, flat cells of the outermost layers as they are pushed upwards to the surface while the dead cells are continuously sloughed off and replaced.  In this way the whole epidermis is replaced about once a month.  This cell turnover process slows down when we are ageing.

The average human epidermis also contains around 5 million skin pores.  More about their important function hereunder.    

The dermis is a thick, supple and sturdy layer of connective tissue and makes up about 90% of the skin’s thickness.  The dermis is a dense network of collagen and elastin fibres.  This network supports tiny lymph and blood vessels that allow the skin to breathe and be nourished, as well as nerves, muscle cells, sweat and sebaceous glands and hair follicles. 

The sebaceous glands produce sebum: an oily/waxy substance which is meant to lubricate and waterproof the skin.  Most sebaceous glands are found in the skin of the face and the scalp; however they are present all over our body (except in hand palms and foot soles).

The activity of the sebaceous glands increases during puberty (and during the menopause) due to an increased level of androgens (= male hormones).  Also stress, environmental circumstances, certain medicines or food supplements can influence the activity of these glands.

In areas of hair growth the glands are connected to the hair follicles and the sebum is transported to the surface along the hair shaft.  In hairless areas (eyelids, nose, genitals) the sebum traverses ducts that end in the skin surface.

The hair shafts (follicles) or sebum ducts end in skin pores, visible on the epidermis. The pores allow sebum and dead cells to be transported out of our skin.  By the end of a day our skin is literally coated with a mixture of sebum, dead cells, crystals left behind by dried sweat and dust and dirt from the environment.

The subcutaneous is the deepest layer of the skin, composed primarily of fat.  It manages the skin’s functions of feeding, excreting and exchanging heat.  The key cells are fat cells (or “adipocytes”) that provide energy and serve as a heat insulator to maintain our body’s temperature and as a shock absorber to protect underlying tissue and organs. 

What can go wrong?

The most obvious thing that can go wrong is that the skin “exhausts” get blocked: clogged pores.  Oil, dead cells and debris get stuck in and around the pores, while at the same time the dermis continues pushing sebum and new soft cells upwards through the follicles or ducts.  Bacteria (particularly the Propioni Bacteria) will get entrapped in the follicles, which will become a perfect breeding ground for them and in no time you will develop blackheads, whiteheads and even acne.

What to do?

There are 3 basic rules to keep your skin healthy:  drink enough water, stay out of the sun (if you cannot: wear good protection) and keep your skin clean.

The latter one you do by taking showers and baths and saunas: hot water and soap will normally rinse the skin of your body sufficiently to remove oil and debris and keep your pores clean.   

For your face however, where the concentration of sebaceous glands is much higher, hot water and soap may not be enough.  And that is where Hydroxy Acids enter the arena.

The benefits of Hydroxy Acid products.

Hydroxy Acids will break up the oil (sebum) that is present in the pores.  By breaking the bonds of the chemical components of the sebum, your skin will become less prone to inflammatory reaction which often results in pimples or acne.

Daily use of Hydroxy Acids will keep a minimum of oil in and on the skin and at the same time keep the acidity of the epidermis at a level that will scare off or kill bacteria.  It also takes off the top layer of the epidermal cells so the pores will remain clean and sufficiently oxygenated and the regeneration process which takes place in the dermis will be accelerated (which is good because remember: it slows down in ageing skin). 

The presence of the Propioni Bacterium is one of the causes of blackheads, whiteheads and acne.  Since this is an anaerobe bacterium it will die when exposed to oxygen: the use of Hydroxy Acid products will prevent the outbreak of acne.  And once acne has left scars on the skin Hydroxy Acid, by continuously peeling off the top layer of the epidermis, will slowly reduce the depth of the scars until they will finally disappear.  

Side effects of Hydroxy Acid products.

If used at an adequate concentration there are very little or no side-effects.  For sensitive skin we advise to use low concentrations, maximum 10% for Alpha Hydroxy Acids and 15% for Poly Hydroxy Acids.  For normal to oily skin you can use up to a 30% strength.

It is advisable however to start at a lower concentration and frequency and to increase gradually. For example starting with a 10% concentration once a day, then twice a day and when your skin is used to the acid, you can gradually increase the strength. 

If the concentration used is too high redness and irritation may occur.  These are only temporary and will disappear quickly however it is advisable in that case to lower the concentration and/or the frequency for some time and then to increase again when your skin is at ease.

Warning: Since Hydroxy Acids remove the oil from your skin your natural protection against UV-A and UV-B sunrays is gone, so it is imperative to always use a good sun protecting cream, even in winter.  Be aware that UV-A rays are present in all daylight and they are the ones that cause your skin to age prematurely.  UV-B rays are short waves which will burn your skin in summer.


If you are concerned about keeping your skin clean, healthy and shining – no matter what your age is – you could consider starting to cleanse your face with a hydroxy acid face wash such as NeoStrata Skin Active Exfoliating wash with 8,5% Gluconolactone and Maltobioic Acid (PHA’s) or NeoStrata Foaming Glycolic Wash with 20% Glycolic Acid (AHA).

If you are new to this: start with the NeoStrata Skin Active Exfoliating wash, once a day in the evening, then twice a day and when your skin is absolutely used to the acidity and shows no adverse reactions, change for NeoStrata Foaming Glycolic Wash which again you can start to use in the evening and in a later stage twice daily.  Apply it on wet skin, with your (clean) hands, make sure to massage it all over your face and forehead, don’t forget your nose and the area around it but make sure to avoid your eyes.  Rinse abundantly.

If you want to go further there are a lot of NeoStrata products which can be applied for the day or the night.  Check out our website: in the search box select “NeoStrata” and “Anti-Ageing” or “NeoStrata Skin Active”.  Find the products that match your skin type and your expectations.  Always start with low concentrations and gradually increase the frequency of use or the strength of the product. 

A good idea for newcomers is to start with the NeoStrata Skin Active range which was especially developed for more sensitive skins and uses the more gentle Polyhydroxy Acids (PHA’s).  The NeoStrata Skin Active Anti-Ageing Kit which we have put together includes an exfoliating wash, a day and a night cream and an intensive eye therapy.  

NeoStrata Company Inc. located in Princeton NJ develops and markets a comprehensive range of clinically proven, dermatologist developed skin care products featuring Alpha Hydroxy Acids and Poly Hydroxy Acids to meet the needs of every skin type.  The company was founded by Drs. Van Scott and Yu who are internationally recognized for making the ground breaking discovery that Alpha Hydroxy Acids have profound beneficial effect on human skin.  They are holders of over 100 US and international patents.  NeoStrata Company Inc. is the absolute market leader in AHA and PHA products and a selection of their products which we tried, trust and recommend, is available on our website.