Chemical exfoliants and retinoids are often considered an essential part of any skincare routine, but which is more important? How do lactic acid vs retinol differ? Can you use them together?
The short answer is yes, you can use lactic acid and retinol together, as long as you don’t experience any skin irritation.
Here’s the longer answer…
Lactic acid is an alpha-hydroxy acid (AHA) that’s made from the sugars found in milk (lactose). It is naturally present in your skin as part of the natural moisturizing factors (NMFs) which means that it makes an excellent moisturizer.
It’s generally less irritating than glycolic acid (depending on product formulation) and, due to its hydrating properties, may be more suitable if you have drier skin.
The main benefit of AHAs, like lactic acid, is that they help exfoliate your skin. It’s thought that they do this by removing the calcium ions from the bonds that hold your dead skin cells together which weakens them and allows exfoliation to take place.
Lactic acid also helps to:
- Improve fine lines and wrinkles
- Improve skin texture
- Brighten skin
- Reduce enlarged pores
Retinol is a form of vitamin A that converts to retinoic acid (its active form) when it penetrates your skin. It helps treat a wide-range of skin conditions and is one of the only skincare ingredients that’s clinically proven to alter your skin on a cellular level.
It’s an antioxidant that increases the rate that your skin makes new skin cells and moves them to the surface of your skin in order to be shed. It also:
- Boosts collagen production
- Reduces inflammation
- Helps prevent acne scarring
- Helps unclog pores and treat acne
- Reduces pigmentation by preventing melanin production as well as getting rid of existing pigmentation by increasing skin cell turnover
- Improves the appearance of fine lines and wrinkles.
Unfortunately, retinol is renowned for causing skin irritation – particularly when you first start using it. It can also damage your skin barrier if used improperly which can make a lot of skin conditions worse and take a long time to correct.
However, as it requires a few conversions to reach its active form, it’s less irritating than other retinoids (e.g. tretinoin, retinal, differin).
Lactic Acid vs Retinol
Both lactic acid and retinol increase the rate of skin cell turnover (your skin’s natural exfoliation process) but in different ways. Retinol encourages the production of new skin cells and increases the rate that these cells travel to the surface of your skin.
It’s a common misconception that retinol has an exfoliating effect because it can cause your skin to flake and peel. However, this is actually a sign of damage to your skin barrier and dehydration.
In contrast, lactic acid acts at the surface of your skin to weaken the bonds between dead skin cells in order for them to be shed faster.
This means that lactic acid and retinol actually compliment each other and may enhance each other’s effects.
Both lactic acid and retinol can help hydrate your skin as well. Lactic acid acts as a humectant to help draw water into your skin cells and keep your skin looking plump. In contrast, retinol encourages the natural production of hyaluronic acid in your skin.
Can You Use Lactic Acid and Retinol Together?
When it comes to layering skincare products and ingredients, the biggest concerns most people have relate to:
- Whether the combination of ingredients will cause skin irritation
- Whether differing pH levels will cause ingredients to ‘cancel each other out’.
Lactic Acid vs Retinol Optimum pH Levels
pH is a measure of how acidic or alkaline a substance is. The pH scale ranges from 1-14 with 7 indicating a neutral pH.
Retinol has to convert to its active form (retinoic acid) in order to exert its effects but it can’t do this until it has penetrated your skin and requires a process called ‘esterification’ to do so. The enzymes that allow this process, and the expression of vitamin A during skin cell turnover have a ‘low optimum pH of about 5.6’.
In contrast, lactic acid is most effective at a much lower pH of 3.5.
However, even when lactic acid is used at a low pH, it still has to adjust to your skin’s natural surface pH (around 5.0 – 6.0, although it can be as low as 4.7 if you haven’t used any skincare products recently).
In addition, while retinol’s optimum pH falls within the range of normal skin pH, the research that it may not function properly at a lower pH may be outdated (the study was published in 1982).
Research also suggests that other acidic ingredients can stabilize retinol and increase its effectiveness.
Therefore, it’s highly unlikely that the pH difference between lactic acid and retinol are an issue.
But what about irritation potential?
Potential Issues When Using Lactic Acid and Retinol Together
Lactic acid and retinol can both cause skin irritation, especially if you have dry or sensitive skin, and this may be enhanced if you use them together. If you experience flaking and peeling, you may want to reduce the frequency of use of either/both lactic acid and retinol or use them on alternate nights.
However, some research suggests that glycolic acid and retinol can be well-tolerated when used together so the same may be true of lactic acid.
The combination of lactic acid and retinol was also well-tolerated when used in a multi-ingredient product. It also improved the signs of sun damage (fine lines, wrinkles, hyperpigmentation, etc.)
If you’re thinking of layering retinol with chemical exfoliants then lactic acid would likely be less irritating than glycolic acid due to its hydrating effects.
However, another thing to bear in mind, especially for those with acne-prone skin, is that both lactic acid and retinol can cause skin purging. This is an initial breakout of spots and pimples that is caused by use of products that increase skin cell turnover. These spots and pimples would have appeared eventually, however, it can be alarming when they all come to the surface of the skin at once.
How To Use Lactic Acid vs Retinol
As it’s a chemical exfoliant, lactic acid should be used a maximum of 1-3x per week in order to prevent skin barrier damage and irritation.
Retinol can be 1x per day but it’s usually better to build up to this gradually in order to reduce the risk of irritation.
For example, using retinol once a week for 2 weeks, then twice a week for two weeks, and so on. If you have sensitive skin, you may prefer to use retinol a maximum of 1-3x per week. Research suggests that it’s still effective when used at this frequency although your results may be slower.
Both lactic acid and retinol are better suited to nighttime use as this is when your skin’s natural exfoliation process is at its highest. Retinol is also easily degraded by sunlight which is another reason to use it at night.
It’s important to wear sunscreen everyday to keep your skin healthy and this is even more important if you’re using ingredients like lactic acid and retinol as both ingredients increase your skin’s sensitivity to the sun and your risk of sunburn/damage.
If you’re not currently using lactic acid or retinol in your skincare routine, you should only introduce one ingredient at a time. After a month, if your skin isn’t irritated, you can add in the other ingredient.
If you’re torn on which ingredient to introduce first, my personal opinion is that retinoids are more important than chemical exfoliation (if your skin is adequately hydrated it’s pretty good at exfoliating itself).
Summary – Which Is Better, Lactic Acid vs Retinol?
Lactic acid and retinol are two ingredients with similar, yet different mechanisms of action. Lactic acid works on the surface of your skin to remove dead skin cells while retinol works deeper in your skin to encourage the production of new skin cells.
If you’re trying to decide between lactic acid vs retinol, retinol is probably slightly superior as an ingredient.