How to use face acids and how to choose the right one for you 

 Key takeaways:

• AHAs and BHAs are exfoliating agents and are the two primary types of face acids, but salicylic acid, a BHA, is more suitable for exfoliating acne-prone or oily skin.
• Hyaluronic acid is neither an AHA nor BHA but is worth mentioning as many products contain this ingredient and is great for skin hydration. 
• Choosing the best acid for your skin is dependent on your skin type and conditions.

 What are face acids?

Face acids are active ingredients typically found in skincare products like cleansers, serums, and moisturizers. They are known to brighten the skin, treat or prevent acne breakouts, and reduce wrinkles. 

Face acids didn't emerge in recent times; rather, their use has only gotten significant scientific backing and has been made easier to incorporate into skincare routines. In the past, European women used stale wine containing malic acid and tartaric acid to cleanse their skin.

Acids in skincare are divided into two common types: alpha-hydroxy acids (AHAs) and beta-hydroxy acids (BHAs).

 Alpha-hydroxy acids (AHAs)

AHAs are commonly used for exfoliation and are also referred to as peeling agents, although the extent of their exfoliating or peeling power is dependent on the concentration of the acid and its pH. 

Examples of AHAs are:

• Glycolic acid: The small molecular size of glycolic acid allows for deep penetration into the skin, making it effective in exfoliation and unclogging pores. Although it can be harsh on sensitive skin, hence a patch test is necessary before use.
• Tartaric acid: This is a gentle exfoliator, which makes it suitable for all skin types. It has antioxidant and anti-aging properties and, over time, can help to decrease the appearance of dark spots. It also works as a pH adjuster and product stabilizer when it is used with other skincare products.
• Malic acid: Malic acid exfoliates the skin, hydrates, and deals with uneven skin texture and hyperpigmentation.
• Citric acid: This is an exfoliant and combines well with other ingredients. For example, when used to form an ester, it creates a physical barrier on the skin and prevents excessive moisture loss. While citric acid is great for all skin types, it can cause irritation in some cases, like exposure to sunlight without sunscreen.
• Lactic acid: Lactic acid is a common AHA derived from milk. Its large molecular size makes it gentler on the skin, therefore making it suitable for sensitive skin. It exfoliates the skin and brightens skin complexion.

Some benefits of including AHAs in your skincare routine include:

1. They are used to treat acne scars, melasma, and hyperpigmentation.
2. They help to smooth out wrinkled skin.
3. They have antioxidant effects.

 Beta-hydroxy acids (BHAs)

BHAs are another group of face acids used for exfoliation. The difference between AHAs and BHAs lies in the fact that BHAs are oil-soluble. That is, they penetrate deeper into the skin to unclog pores, and this makes them ideal for people with acne-prone or oily skin.[6]

An example of BHAs is:

• Salicylic acid: It is the most common BHA found in many skincare products and is oil-soluble, therefore making it ideal for oily and acne-prone skin as it can penetrate clogged pores and combat acne, whiteheads, and blackheads.

Some benefits of including BHAs in your skincare routine include:

1. Deeper exfoliation: Because they're oil-soluble, BHAs are able to penetrate deeper into the pores and exfoliate both the outer layer of the skin and the inner layer, therefore making them stronger exfoliants than AHAs.
2. Tighten pores: They can reduce the look of large pores that are outlets for acne. 
3. Useful for treating acne: BHAs are great for acne-prone skin as they can combat acne and reduce oiliness.
4. Reduce wrinkles: They reduce the appearance of wrinkles and fine lines. 

 How to use some of the common acids

This is a breakdown of how to use the acids mentioned above.

 1. Glycolic acid

This acid can be used as a face wash,  toner, serum, or mask. Here is how to use glycolic acid for an optimal result:

• Cleanse: Cleanse your skin to prepare it for the acid. A mild cleanser is ideal.
• Start small: If you're new to using face acids in your skincare routine, start with a lower concentration. This will help your skin gradually recognize the new addition and adapt. This goes for using any facial acid. 
• Tone: Using a mild toner before applying the glycolic acid helps balance the acid's pH to maximize its effectiveness. 
• Patch test: A patch test is advised to determine your skin's sensitivity to the product, especially as glycolic acid is an exfoliant. Apply small on a small portion of your skin and leave it on for some time. If it looks good and there are no irritations, go ahead and apply it on your face.
• Skip other exfoliating products: Use only one exfoliant at a time, as doing the opposite might lead to irritation and breaking of the skin barrier. When using glycolic acid, avoid physical exfoliants like scrubs.
• Hydrate and moisturize: Use serums or lotions that contain hydrating ingredients like hyaluronic acid and use natural oils to lock in the moisture.
• Be generous with sunscreen: When using glycolic acid during the day, make sure to use sunscreen generously, as an exfoliant like glycolic acid can make the skin more photosensitive to UV rays. 

 2. Tartaric acid

It is advisable to use this AHA during your evening/nighttime routine, as using it during the day can increase your skin's photosensitivity.

Here is how to use tartaric acid:

• Cleanse: First, use a gentle cleanser to remove dirt and prepare your skin for the acid.
• Patch test: Again, this should be observed before introducing a new skincare product to your routine.
• Concentration: If you're new to it, start with a low concentration of about 5%, then feel free to increase it if you're sure your skin is ready for more.
• Frequency: It is recommended that you start at an interval of about 2 to 3 nights and then increase the frequency if your skin tolerates it.
• Combine other actives: Unlike glycolic acid, which can work alone effectively, tartaric acid needs to be combined with other actives like glycolic or lactic acid for it to be effective. However, the other paired acids should also be in lower concentrations to avoid the risk of burning. Also, a stronger exfoliant like salicylic acid should be avoided when pairing.
• Moisturize your skin.
• Use sunscreen: Although it is advised you include tartaric acid in your nighttime skincare routine, sunscreen must still be included in your day time routine.

 3. Malic acid

Here is how to use malic acid:

• Cleanse.
• Patch test: Even though malic acid is mild on the skin, it is advisable to patch test before full application.
• Apply malic acid: It can be used on its own, but for faster result, use with other AHAs, although, apply with caution as malic acid can still cause irritation, especially for sensitive skin.
• Moisturize after applying it.
• Sunscreen: If it is used during the day, ensure you wrap up your routine with a broad-spectrum SPF.

NOTE: It is best to avoid the area around the eyes when applying malic acid, as the skin in that area is super sensitive.

 4. Citric acid

Here is a step-by-step process for using citric acid:

• Cleanse.
• Pair with other AHAs and BHAs: This is to elevate the effectiveness of the citric acid, but remember to tread carefully if you have sensitive skin.
• Steer clear of physical exfoliation like scrubbing.
• Moisturize your skin.
• Avoid using citric acid if retinoid is part of your routine, as retinoids contain a higher concentration of the active ingredient, retinoic acid. Citric acid can be used in the morning, and retinoids best used at night.
• Again, use sunscreen.

 5. Lactic acid

Use your lactic acid this way:

• Cleanse your face using a facial cleanser.
• Do a patch test. 
• Apply lactic acid: One of the best ways is to get lactic acid into your skin is through a serum.
• Avoid pairing it with other AHAs and BHAs, especially not with retinol, as they can irritate the skin.
• Moisturize your skin
• If lactic acid is part of your skincare routine, for the umpteenth time, do use a sunscreen. 

 6. Salicylic acid

• Cleanse
• Start small: Salicylic acid is a BHA, meaning it has stronger exfoliating effects than the AHAs; therefore, it's best to start with a lower concentration.
• Apply: SA is present in many formulations and can come on its own as a serum.
• Hydrate and moisturize: One of the side effects of salicylic acid is its ability to dry out the skin; therefore, you need to go heavy on hydrating and moisturizing your skin when using it.
• Protect: AKA, use sunscreen.

 Hyaluronic acid

Hyaluronic acid is neither an AHA nor a BHA but a humectant, which means it has hydrating effects. Hyaluronic acid can be used together with AHAs or BHAs to help reduce irritation. It also gives the skin a plump, hydrated, and youthful look. 

 Kojic acid

Like hyaluronic acid, kojic acid is neither an AHA nor a BHA but has potent brightening effects. If you have sensitive skin or are including AHAs or BHAs in your routine, it is advisable to avoid products containing this acid. 

 Choosing the right face acid for you

Choosing the right acid for your skin is dependent on your skin type and the condition(s) you want to treat. And if you're not sure of your skin type, that'd be your cue to visit a dermatologist. 

The table below shows a detailed overview of the ideal acid to use according to different skin types and conditions.

It is obvious that the majority of these acids have a caveat for sensitive skin. Therefore, if you have sensitive skin and would like to incorporate acids into your routine, rather than going through multiple trials and errors, which can be a tad bit of time and money-wasting, consult a dermatologist to tailor the right products according to your skin needs.

 Wrap up

AHAs and BHAs are safe to use as exfoliators but should be done with caution, especially if you're new to them or have sensitive skin.

Most importantly, visit a dermatologist before going for these acids with higher concentrations, and avoid or stop their use if you have open wounds, irritations, allergies, or are pregnant.