Dr. Shreya Andric is a dermatologist based in Sydney. She is passionate about skin health and her mission is to educate the public on how to care for their skin, and also clear up the vast amount of misinformation out there on this topic.
While Dr. Andric has independently chosen the products that appear in this article, she does not receive revenue from the links. Some of the links may return revenue to Yahoo Lifestyle Australia.
AHAs and BHAs - What are they?
Exfoliation is the process of removing dead skin cells from the surface of your skin. There are multiple reasons why one would exfoliate their skin and it can be done one of two ways – chemically or physically.
Physical exfoliation uses a tool, eg, a brush or a scrub to physically remove the dead skin cells. In general, chemical exfoliation is preferred as physical exfoliation can irritate the skin, resulting in microtears and inflammation. If done properly, however, eg, an in-clinic microdermabrasion, physical exfoliation can offer more dramatic results. Chemical exfoliation uses chemicals, eg, alpha and beta hydroxy acids, to gently dissolve dead skin cells
At a microscopic level, the epidermis (the outermost part of the skin) resembles a layer cake. The stratum corneum is the top layer and the stratum basale is the deepest layer. The “fresh” skin cells are made in the stratum basale and they slowly make their way upwards to the stratum corneum where they die and are eventually shed.
In babies, this process can take as little as seven days. As we grow older, the process takes longer and longer – 28 days in your 20s and 30s, 45-60 days in your 40s and 60-90 days over the age of fifty. When the dead skin cells are sitting on the surface of the skin, it gives a rough, dry, flaky appearance as well as clogged pores.
In the short term, exfoliation can result in a brighter complexion and can also improve the effectiveness of skincare products by enhancing absorption. Unclogging pores helps to reduce the frequency of breakouts. Long-term, exfoliation can increase collagen production, which promotes skin elasticity and minimises the appearance of fine lines.
These are a group of water-soluble acids, which are mostly derived from sugary fruits. The most popular AHAs include:
Glycolic acid (from sugar cane)
Lactic acid (from milk)
Citric acid (from citrus fruits)
Tartaric acid (from grapes)
Malic acid (from apples)
Citric, tartaric and malic acid do not penetrate the stratum corneum as well as glycolic and lactic acid which can actually be a good thing for more sensitive skin.
Studies have shown that when AHAs are applied consistently to rough dry skin, increased cell turnover results in a smoother, less scaly surface. Patients report improvement in dry skin, acne, as well as sun spots.
One study showed use of 25% glycolic, lactic or citric acid to the forearm for 6 months showed an approximately 25% increase in skin thickness, without any inflammation.
That being said, most available daily-use AHA preparations contain a lower concentration of active ingredient than that used in the clinical trials.
When used in combination with a topical retinoid (at different times of the day, eg, AHA in the morning, retinoid at night), there has been found to be more benefit than using a retinoid alone.
Some good examples of AHA products include Skinceuticals Glycolic 10 Renew Overnight, Sunday Riley Good Genes Lactic Acid Treatment, and The Ordinary AHA 30% + BHA 2% Peeling Solution (a great weekly mask).
As opposed to AHAs, which are water-soluble, BHAs are oil-soluble, which means they can go deep into your pores to clear them out.
Because of this, BHAs are generally used to treat acne, as well as sun damage. Salicylic acid is the most common BHA. Its use in treatment of acne is well-known but it can also reduce redness as well as inflammation.
It is important to note that while AHAs are mostly safe in pregnancy, salicylic acid should only be used in concentrations less than 2%. My favourite salicyclic acid products include the Effaclar range from La Roche Posay or Ego’s Elucent range.
Which acid is best for your skin type?
It is important to be mindful of your skin type before jumping into exfoliation. I’ve said it before and I’ll say it again – skincare is not one size fits all! When starting with a new skincare regimen, introduce one product at a time (eg, one per week) so as not to overwhelm and irritate your skin. Choosing the right products for your skin type will minimise the risk of irritation and help you to achieve the best possible result.
Most people with normal skin can try any exfoliating technique/product without experiencing adverse effects. Ultimately it comes down to personal preference.
AHAs are best for people with dry skin as they can break through the top layer of the skin allowing a moisturiser to penetrate deeper and hydrate the new skin cells more effectively.
Oily skin can in general handle stronger chemical and physical exfoliators. They may consider weekly at-home microdermabrasion in between clinic treatments.
This is characterised by a mix of oily and dry areas. Each area should be treated individually - for example, if you have an oily T-zone, you may choose to use a chemical exfoliator or scrub on one day, then a low-level AHA to any dry areas the next day.
Choose salicylic acid-based products. Wash off products can be helpful for acne-prone skin that is also sensitive. Neutrogena’s acne wash is a good option.
Sensitive skin is characterised by skin that stings or is otherwise irritated after using new products. BHAs are typically less irritating than other chemical or physical exfoliants. Sensitive skin can be a symptom of an underlying condition such as eczema or rosacea so it is worthwhile speaking to your GP or dermatologist if you’re having trouble getting on top of it.
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