Ingredients Not to Mix in Your Cosmetics

Omy ingrédients à ne pas mélanger niacinamide et vitamine C

Whether your beauty routine contains 20 products or a simple moisturizer, you ought to know the compatibility of the active ingredients in your cosmetics. First to maximize the effectiveness of your care, and second to avoid irritating your skin.

Welcome to your Active Ingredient Mixology 101 course
. On the menu, the combinations of active ingredients to avoid, and our tips for getting around the side effects of these combinations.

Vitamin C 

Vitamin C has multiple virtues: it improves the uniformity of the complexion and minimizes the appearance of wrinkles. Thanks to its antioxidant properties, vitamin C also protects the skin from oxidative stress caused by the external environment which damages the structures of the skin (1).

  • Vitamin C and Retinol

Vitamin C and retinol are the perfect combo to diminish the appearance of wrinkles and hyperpigmentation. These two ingredients work hand in hand: retinol stimulates cell turnover and collagen production while vitamin C protects skin integrity with its antioxidant power.
Although this combination works wonders for the skin, it should be done with care
. Indeed, these two ingredients can be irritating to the skin. To minimize the risk of irritation and maximize results, it is strongly recommended to alternate the time of application of these two products. For example, you could apply your vitamin C in the morning and your retinol in the evening.

  • Vitamin C and Niacinamide 

Cosmetics containing pure vitamin C are often formulated at an acidic pH to maximize the effectiveness of this ingredient. It is this acidity that makes vitamin C-based products often irritating.

However, niacinamide is incompatible with an acid pH. Indeed, when niacinamide comes into contact with an acidic environment, it can be transformed into niacin. This compound can temporarily create redness on your skin. Because the niacinamide is transformed into another form, you lose its effectiveness. Thus, it is not really vitamin C and niacinamide that are incompatible, but rather acidic pH cosmetics and niacinamide.
To work around this incompatibility, you can alternate the application of your niacinamide and your vitamin C. For example, you could apply one product in the morning and the other in the evening. You could also alternate the application of each product every other day.
Besides this trick, cosmetics made with vitamin C derivatives are an excellent alternative to avoid irritating your skin. Cosmetics containing these derivatives (ascorbyl glucoside, tetrahexyldecyl ascorbate, ethyl ascorbic acid, etc.) can be formulated at skin pH, which makes them milder. By choosing a product containing a vitamin C derivative, you can apply it at the same time as your niacinamide without having to worry about a compatibility problem.

Discover the Benefits of our Pure Vitamin C Oil

Discover Omy's pure oil, a product formulated with 5% stabilized vitamin C. Its minimalist formula allows you to combine your vitamin C with your other active ingredients.
Once in contact with the skin, stabilized vitamin C releases vitamin C in its active form into the epidermis with the action of skin enzymes. This treatment will help you preserve the hydration of your skin and protect it from external aggressions.


Retinol is one of the most effective anti-aging ingredients. However, retinol can often lead to skin irritation and dryness. Retinol is also photosensitizing, i.e. the skin becomes more sensitive to ultraviolet rays from the Sun. It is therefore essential to apply sunscreen every morning and reapply it during the day.

  • Retinol and Exfoliating Acids (AHA/BHA)

Chemical exfoliants such as glycolic acid, an AHA, can be irritating on their own. Their combination with retinol therefore has a high irritant potential. Additionally, retinol performs indirect exfoliation of the skin by stimulating cell turnover

Thus, the use of only one of these two ingredients is often sufficient to work the texture of the skin. If you want to combine these two ingredients, alternate the application of your products with your AHA/BHA in the morning and your retinol in the evening.

  • Retinol and Benzoyl Peroxide

These two ingredients can work wonders for those suffering from acne. However, given their chemical properties, retinol and benzoyl peroxide can cancel their respective activities. That's why it's best to apply your benzoyl peroxide in the morning and your retinol at night.


Niacinamide, also called vitamin B3, is an ingredient that mixes well with the majority of other active ingredients. This vitamin has anti-inflammatory and healing properties, in addition to regulating sebum production and reducing the appearance of hyperpigmentation (2, 3, 4).

  • Niacinamide and Chemical Exfoliants

As mentioned previously, the combination of niacinamide with an acid pH product is not recommended. Thus, applying niacinamide immediately after applying your AHA treatment could irritate your skin.

To get around this drawback, you can alternate the time of application of your AHA treatment and your niacinamide. For example, you could apply your niacinamide during the day and your AHA treatment at night. Or, you could wait 30 minutes between applying your niacinamide and your AHA product to allow time for the niacinamide to soak into your skin.

Discover the Benefits of our Customized Niacinamide Serum

A 5% concentration of niacinamide has been clinically shown to reduce the appearance of hyperpigmentation (3). Plus, niacinamide's anti-inflammatory and healing properties make it the perfect ingredient to soothe your skin. Omy's customized serum is precisely formulated with 5% niacinamide to bring all the benefits of this ingredient to your skin.

Chemical Exfoliants (AHA/BHA)

The family of chemical exfoliants includes alpha-hydroxy acids (AHA) and beta-hydroxy acids (BHA). These chemical exfoliants work in two ways. AHAs slough away dead cell buildup on the skin's surface to reveal a brighter, smoother complexion, while BHAs penetrate pores to help decongest them.

To make it easier to incorporate chemical exfoliants into your routine, you can use them only once or twice a week rather than daily. For example, you could use triple exfoliation (chemical, enzymatic and physical) to effectively exfoliate your skin. A tri-exfoliating mask can be applied once or twice a week for visible results.
Just like retinol, chemical exfoliants can make skin more sensitive to UV rays, so don't forget to put on your broad-spectrum sunscreen!

Natural Extracts

There are hundreds of natural extracts from plants available on the cosmetics market. In general, there are no contraindications for mixing these extracts with other active ingredients. The advantage is that they usually don't photosensitize the skin like retinol does.
Some extracts have similar properties to popular active ingredients like vitamin C and retinol, although their effectiveness differs. For example, dragon fruit extract helps reduce the appearance of dark spots while antioxidant-rich kakadu plum extract helps prevent the appearance of wrinkles. You will find these extracts in Omy's personalized skincare under the ingredient names Ta and Ox respectively.
If you have any questions about mixing your active ingredients, do not hesitate to make an appointment with a skin expert to do a skin check-up over the phone.