AHAs vs BHAs: Acids for Your Skin Explained

The ever confusing AHA versus BHA topic. What is AHA and BHA? What’s the difference? How do I choose between them? What type of acid do I use? It’s time to settle this once and for all on here! Honestly, for the longest time, I was confused as well! Until I had enough, and decided to explore this by writing everything out, chatting with other skin enthusiasts, companies, estheticians, etc. So let’s dive right in!

Previously I talked about the importance of exfoliating, and touched upon the differences – physical and chemical.

Related Article: Exfoliating: Basic but Crucial Skincare Step

To break it down for you now, I will talk in depth about the chemical exfoliants.

What is a Chemical Exfoliant?

Chemical exfoliants use different types of acids to dissolve the dulling and dry layers of the skin, along with the buildup of dead skin cells that prevent our skin from achieving the healthy, radiant and smooth look.

There are two categories of chemical exfoliants, Alpha Hydroxy Acids, or AHA, and, Beta Hydroxy Acids, or BHA. Both in which work to gently exfoliate and smooth out rough skin. You can use both; but most experts do not recommend using both at the same time. This will be further explained.

They both can:

  • Smooth and soften rough texture
  • Reduce the appearance of fine lines and wrinkles
  • Provide hydration
  • Brighten and even out skin tone
  • Unclog pores

What is AHA?

Alpha Hydroxy Acids, or AHAs, are a group of plant and animal-derived acids that are used in a variety of skincare products. They are water-soluble carboxylic acids made from sugars and fruits that help exfoliate the skin. According to Science Becomes Her, AHAs work by removing calcium ions from the bonds that hold skin cells together which weakens the bonds and allows exfoliation to take place.

AHAs are commonly used to treat the signs of sun-damage (photoaging), such as fine lines and wrinkles, enlarged pores, uneven skin tone and skin pigmentation. Generally AHAs are suitable for all skin types, however, those with sensitive skin need to gradually build up a tolerance to avoid irritation.

Not all AHAs have the same exfoliating power though. It is determined by the type of AHA you use. The rule of thumb here: the more AHAs contained in a product, the more powerful the exfoliating effects. That means, the highly concentrated peeling effects of AHAs make you more sensitive to UV rays. So, it is suggested to apply sunscreen daily and reapply more frequently to prevent sunburn. The higher the concentrates, the easier you are at risk for irritation, sunburn, and even chemical burns.

Benefits of AHAs


Obviously we know that all AHAs are generally exfoliating. Exfoliation is the foundation for all other benefits that AHAs offer. Exfoliation refers to the process where skin cells on the surface shed. This helps to remove dead skin cells and make room for new cells to form. As you age, your natural skin cell cycles slow down, which makes dead skin cells build up easier. If you have too many dead skin cells, your complexion will look dull. And in turn, the accumulation of dead skin cells can enhance other issues such as wrinkles, age spots and acne.

Collagen Promotion and Blood Flow

Collagen is a protein-rich fiber that keeps your skin plump and smooth. As you age, these break down, causing sun damage to accelerate due to the collagen destruction, resulting in saggy skin. Collagen itself is in the middle layer of your skin (dermis). When the upper layer (epidermis) is removed, products such as AHAs work on the dermis. The anti-inflammatory properties in AHAs help to promote blood flow, which help to correct pale, dull complexions. Proper blood flow ensures skin cells are getting the necessary nutrients needed.

Correct Discolorations from Scars and Age Spots, and Brighten Complexions

The risk for discoloration increases as you age. Brown spots may develop as ar esult of sun exposure, which tend to develop on areas most exposed to sun such as your chest, hands and face.

Improve Appearance of Surface Lines and Wrinkles

Surface lines and wrinkles, not deeper wrinkles. According to Healthline, the only methods for deeper wrinkles are professional fillers, as well as laser resurfacing.

Prevent Acne Breakouts

Exfoliating with AHAs can help loosen and remove the clog. Continued use may prevent future clogs from forming. AHAs may reduce the size of enlarged pores, which are commonly seen in acne-prone skin. Skin cell turnover from exfoliating glycolic and lactic acids reduce acne scars. Some acne products like citric and malic acids, help soothe inflamed skin.

Increase Product Absorption

Yes you read this right! If you have too many dead skin cells, your daily moisturizer is just sitting at the top of your skin, without hydrating the new skin cells forming underneath. AHAs like glycolic can break through the dead layers of skin cells, enabling your moisturizer to hydrate your new skin cells more effectively.

Types of AHAs

Citric acid is made from citric fruits and has the largest molecular weight among AHAs. They’re often added into skincare products to adjust the pH level closer to the skin’s natural pH levels.

Glycolic Acid is most commonly used and is made from sugar cane plant. It is the smallest molecular weight among AHAs which means that it is better able to penetrate the skin and can be more effective. Though it has potential to become more irritating.

Lactic Acid is another well known AHA made from the sugars of milk (lactose). This is naturally present in our skin as part of natural moisturizing factors, which makes it an excellent moisturizer. Generally, it is less irritating than glycolic acid, and with its moisturizing properties, it may be more suitable for those with dry skin.

Malic Acid is made from the acids found in fruits such as apples, but can be created synthetically. Less effective than both GA and LA, which is likely due to its larger molecular weight. However, it may enhance effects of other acids when used in combination.

Tartaric Acid is derived from grapes, and is known to have antioxidant properties.

Mandelic Acid is derived from almonds. These have bigger molecules than LA so it does not penetrate your skin as fast, and effects are much slower. Great for people who have very sensitive skin that is easily prone to rashes or irritation. Great for those who want a routine acid that gives the AHA power without needing drastic results immediately.

What is BHA?

Beta Hydroxy Acid, otherwise known as BHAs, this acid usually comes in the form of salicylic acid, and is most commonly found in exfoliating products relating to acne and blemished skin. They tend to work deeper in the pores of the skin than AHAs as they are attracted to oil. BHAs are oil soluble, meaning they get down into the pores to cut through the oil that’s clogging them. They have antibacterial and anti-inflammatory properties. So, BHAs are perfect for treating acne-prone skin and blackheads.

Like AHAs, BHAs can also make your skin vulnerable to damage from the sun. So always use a moisturizer containing SPF 15 or higher.

As mentioned, the most common BHA ingredients are salicylic acid (or related substances such as salicylate, sodium salicylate, and willow extract). Other ingredients include Beta Hydroxybutanoic Acid, Tropic Acid and Trethcanic Acid.

Salicylic Acid

Salicylic acid is used as a cosmetic ingredient. It occurs naturally in willow bark and sweet birch. It is not as irritating as glycolic acid (the strongest AHA) due to its large molecular size, as well as its anti-inflammatory properties.

The FDA notes that “the use of salicylic acid related substances in cosmetics is “safe as used when formulated to avoid irritation and when formulated to avoid increased sun sensitivity.” CIR added that “when sun sensitivity would be expected, directions for use [should] include the daily use of sun protection.”

Betaine Salicylate is a BHA derived from sugar beets. It is a gentler alternative to salicylic acid.

Salix Alba or Willow Bark Extract is a natural BHA extract from plants. Although the salicin content converts into salicylic acid, it is much weaker, therefore it won’t give you the comparable results for exfoliating or treating acne.

Major Differences between AHA and BHA

To make things a little easier, I have attached a gallery of graphics you may find useful!
(Note: these are not my graphics; credits goes to Science Becomes Her and @SarahtheCara)


To summarize some takeaway points, the major differences as The Skincare Edit summarizes beautifully are:

  • Solubility: AHAs are water-soluble, so they dissolve in water. BHAs are oil-soluble, so they dissolve in oils (meaning they can pass through sebum and sebaceous follicles)
  • Area of Action: AHAs work on the top layers of skin, whereas BHAs work inside the pores AND on the surface
  • Concentration: According to Dr. Albert Kligman, AHAs need to be used in concentrations of at least 8% in order to be effective, whereas BHAs only need a concentration of around two percent, though it can be found as low as 0.5%
  • Decreasing oil production: AHAs do not have an effect on sebum. BHAs reduce excess oil by slowing down sebum production.
  • Clearing and preventing acne, blackheads and clogged pores: Both can help with mild acne. BHAs work on deeper level to clear trapped sebum in pores and prevent clogs from forming. They slow down oil secretion and loosen blackheads making them easier to extract
  • “Shrinking” pores: Technically this is not possible – but they can appear bigger when they are filled with debris, making them stretch out. AHAs don’t affect pores, but BHAs can help them look smaller by keeping them clean
  • Irritation: BHAs tend to be less irritating due to their molecular and anti-inflammatory properties
  • Photosensitivity: AHAs increase your skin sensitivity, making it more vulnerable to sun damage and pre-mature aging. In contrast, BHAs have some photoprotective effects.
  • Skin wounding: AHAs are skin-wounding agents that encourage cells to self destruct through apoptosis (cell death). BHAs are non-wounding agents, therefore they loosen the bonds between skin cells.

How to Choose and Use Hydroxy Acids

A key aspect is understanding the effectiveness so you know how to use them and how much. It comes down to the way you want the products to work along with your skin concerns. For example, if your skin issues are deeper, like cystic acne or just acne in general, you might want to opt for a BHA (like salicylic acid), or a combination of both AHA and BHAs, as it will penetrate the issue.

If you’re interested in adding some AHAs or BHAs to your skincare routine, here’s what you need to know:

  • Start off slow. When you’re first getting started, you’re going to be tempted to use the highest concentration you can find, and you’ll most likely add it into your daily routine. Do not do this. Though both alpha hydroxy acids and beta hydroxy acids work for all skin types, you need to know how much your skin can tolerate. Start off by testing it on your skin first. Use it once a week for the first few weeks, and gradually build.
  • If you decide to use both AHA AND BHA in your routine, DO NOT LAYER OR MIX YOUR AHAs AND BHAs TOGETHER IN YOUR DAILY ROUTINE. Apply every other day. One day an AHA, and the next a BHA. Layering or mixing them daily may not benefit you in the long run. I will touch on the bad effects shortly. You can use them on different areas of the skin; oily and blemish prone areas you can apply a BHA like Salicylic Acid
  • Know what to expect. Do some research on the different types of acids, and study your skin. Examine your skin and know what you want to target specifically, that will help you.
  • Follow up with SPF! Always! You already should be using sunscreen *ahem, however, when you use AHAs, be sure to use sunscreen as AHAs are known to increase the skin sensitivities to UV rays, and limit your sun exposure.
  • Hydrate. And protect your skin!

Tip: The Cleveland Clinic recommends starting with a product with a maximum concentration of 10% to 15% AHA to avoid skin irritation. In addition, you should only initially apply every other day, gradually working up to daily application.

The Good and The Bad

Where there is good, there is bad! It’s simple when it comes to telling if the products aren’t working together, and knowing how much is too much.

Here are some things to keep an eye on:

  • Do not over exfoliate. Both can be very strong and using them too frequently can cause extreme dryness and irritation.
  • Read instructions carefully. Alternate between two acids to observe how they react.
  • Skin may initially become dry and flaky as cells begin to shed, but this should clear up within a few weeks.
  • Aside from minor peeling, stinging or redness, if your skin feels very tight – no matter how much moisturizer you put on – consider that it is a sign that the chemical exfoliation was too harsh for you.
  • If this happens, stop the use and focus on repairing your skin by giving it time to rest and heal.
  • Using Alpha and Beta Hydroxy Acids can increase the skin’s sensitivity – that is raising the risk of sunburns! Should any side effects become severe, discontinue the use of the product immediately.
  • Inflammation and scarring may be other side effects that occur from an alpha hydroxy. Chemical peels remove dead layers of skin, increasing the risk of infection and inflammation.
  • As a result, if skin doesn’t grow back healthy, not only can scarring occur, but facial herpes infections, cold sores, and increase in those prone to breakouts, along with skin pigmentation.

Hydroxy Products

Hydroxy products come in a variety of percentages, packaging, costs, etc. They are in cleansers, oils, serums, peels, lotions, etc. There are a LOT of products out there, you can purchase many over the counter. Sephora is always a great resource as well to look for products.

Salicylic Acid Face Washes

Face washes with salicylic acid are my favourite! Since this ingredient is very populary, especially for those suffering with acne, you need to look into this. They’re easy to use and can be included into your routine since it’s easier to use than a serum that requires wait time. Though with face washes, it does not come in contact with your skin for a long time, some also do not recommend this. This isn’t usually recommended because usually you would give time for the salicylic acid to work and penetrate your skin. Those that benefit from a face wash are those with sensitive skin who cannot tolerate acids on your skin.

Some popular choices:

  • CeraVe Renewing SA Cleanser
  • Murad Time Release Acne Cleanser


StyleCraze’s 10 Best Salicylic Acid Products listed here!


Other BHA Products

As recommended and broken down by:

Skincarisma: Top 10 BHA Products

Sephora: BHA Skincare Products

AHA Products

As recommended and broken down by:

Sephora: AHA Skincare Products

Simple Skincare Science: Top 5 Picks Using 50 Studies

Skincare Hero: 8 Best AHA Products (For Anti-Aging & Wrinkles)

Glowsly: What is Glycolic Acid? 15 Best AHA/Glycolic Acid Products in Skincare


How to Store Them

To ensure that your products can treat your skin effectively, you should store them properly so that they can maintain their freshness. The Klog shares some tips on how to properly store your acids, and they are as follows:

  • Keep acids in the dark. BHAs and AHAs are more stable forms of acids, which can be kept at room temperature. But despite the stability, you should store them away from direct sunlight. By putting the acids (or any skin care products) in direct sunlight, you expose them to extreme fluctuations of temperature that can alter the potency and shelf life.
  • Storing products in the bathroom may affect it as well. The change in temperature and humidity can change the potency and shelf life.
  • Vitamin C (aka ascorbic acid) is a sensitive acid. The pure ascorbic acid is prone to oxidation. This is a natural chemical reaction that takes place over time, no matter how stabilized it is. During this oxidation process, the ascorbic acid slowly oxidizes into the chemical dehydroascorbic acid, or DHAA. When this happens, your vitamin C will turn from a clear liquid to yellow, and somtimes even a dark brown colour. Once it becomes oxidized, you should discontinue using it as it will no longer be effective. Note: Those that use water in their formulas are more prone to oxidizing quicker.
    • Store your vitamin C in a cool, dark area (your fridge is best). Make sure to close the lid tightly after each use and immediately place the refrigerator.

Other Tips on Storing Skincare Products

  • Dry, Cool Place out of direct sunlight, like in a cabinet, drawer, or lidded storage box in your bedroom
  • Products that are highly sensitive to heat or light like Vitamin C and retinoids, or natural/organic skin care with shorter shelf life can benefit from being stored in the fridge. They will last longer and not break down that easily.

Products that should NOT be kept in the fridge

  • Oil based products like serums can start to separate or become cloudy when they’re stored in the fridge. So its best to keep them away from extreme heat or cold
  • Clay masks. DUH! Otherwise they will harden.



That’s all for now folks! There’s plenty more that can probably be said including the PH levels of your skin in regards to these hydroxy acids as well, but I think PH levels in the skin can be a different spotlight post!

Let me know what you took away from this extensive blog post. Do you currently use any hydroxy acids in your routine? If not, what do you look forward to adding?

As usual, you’ll find me on my social media!

With love,
Pris Wong xo



Note: all of the information regarding this post has been sourced from a variety, and includes my own notes, thoughts, etc. Other links that I have used and may be useful to you are below:






Murad: What are AHAs and BHAs?

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