Regardless of whether your skin is dry, oily, or prone to acne, there are specific skincare ingredients that should never be combined. Mixing various skincare components can lead to deactivation of their properties, skin irritation, or even heightened dryness. For instance, after using AHAs and BHAs for exfoliation, you might consider applying Vitamin C for sun protection and to combat aging — but this mix should be avoided!
According to Dr. Davin Lim, a board-certified dermatologist, some ingredients you should never mix include retinol and retinoids with ascorbic acid or benzoyl peroxide; salicylic acid with AHAs, retinol, or ascorbic acid; and hydroquinone with retinoids or ascorbic acids.
When treating acne or exfoliating your skin, it's crucial to combine skincare ingredients thoughtfully to maximize their effectiveness. An improper blend can lead to discomfort, irritation, and undesirable side effects.
If you lack access to a skincare interaction checker and are unsure about which ingredients to avoid mixing, here are the essential guidelines from dermatologist Dr. Davin Lim.
Which Skincare Ingredients Should You Avoid Mixing?
1) Retinol and Retinoids with Ascorbic Acid
If you've experienced skin irritation, consider using a milder form of retinol, such as original skin polymer tape or hydroxypinacolone retinoate (HPR).
Alpha hydroxy acids (AHAs) are particularly effective for enhancing skin texture, managing surface wrinkles, and smoothing fine lines. For example, glycolic acid, with its smaller molecules, penetrates the skin more easily.
It is crucial not to mix retinol with ascorbic acid and other skincare acids, including AHAs and BHAs. L-Ascorbic acid, commonly known as Vitamin C, and retinol function optimally at distinct pH levels. When these two are combined, they can create a perfect storm for redness, irritation, and peeling of the skin.
Another important factor is that ascorbic acid is water-soluble, whereas retinol, a derivative of Vitamin A, is oil-soluble. Because these two ingredients are insoluble, they should not be mixed.
The primary reason for this is that when retinol, which creates a barrier on the skin, is combined with ascorbic acid, it can prevent the absorption of Vitamin C, rendering it ineffective and wasting both time and money.
2) Retinol and Retinoids with AHA (Alpha Hydroxy Acid)
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Many individuals seek skincare products featuring retinol, retinoids, or alpha hydroxy acids when looking for effective exfoliators. A 2015 study confirmed that combining retinoic acid with glycolic acid is an effective treatment for acne scars.
While AHAs are excellent for improving skin texture, their water-solubility means they predominantly work on the skin's surface, in contrast to the deeper penetration of oil-soluble retinol. This often results in irritation when both are used together, as they can deactivate each other.
3) Salicylic Acid with Retinol
Beta hydroxy acids (BHAs), such as salicylic acid, are oil-soluble and powerful exfoliants. Exfoliating your skin with BHAs can amplify the efficacy of other skincare products. However, this is not a strict rule; dermatologists may suggest using salicylic acid in the morning and a retinol or retinoid product in the evening.
Research indicates that layering retinol with BHAs can lead to dryness, redness, irritation, flaking, and increased skin sensitivity. When using salicylic acid and retinol, it's advisable to apply them sequentially rather than simultaneously.
Thus far, we've discussed skincare products containing Vitamin A, such as retinoids, as well as Vitamin B, which is generally compatible with most ingredients due to its anti-inflammatory properties, along with Vitamin C.
There are numerous other active skincare ingredients that should be avoided in combination during your skincare routines.
4) Hydroquinone and Retinols
Example of a skincare product containing hydroquinone
Hydroquinone, commonly referred to as HQ, is a potent active ingredient used for treating skin pigmentation. It works by inhibiting the enzyme tyrosinase, which is essential for melanin production.
Mixing hydroquinone with retinol or Vitamin C is not recommended, as these combinations can lead to adverse reactions. However, a product called Triluma combines hydroquinone with hydrocortisone and a retinoid, which may provide anti-inflammatory benefits to counteract irritation.
If you opt to combine hydroquinone with a retinoid, it is essential to manage potential side effects carefully. Pharmacists sometimes recommend a compounded formulation of hydroquinone with a minimal concentration of ascorbic acid (between 0.5-2%) not for its pigment-inhibiting properties, but rather to stabilize the hydroquinone as an antioxidant.
Other skincare ingredients, particularly botanical extracts like burberry, licorice, or witch hazel, can generally be combined with most active ingredients, including vitamins A, B, and C, as well as various acids. This is largely due to the lower irritant threshold of botanical extracts compared to more potent active ingredients.
Conclusion
When mixing skincare products that contain active ingredients, proceed with caution. If you must combine products, start slowly and gradually increase your understanding of your skin's tolerance. Exceeding your skin's threshold for active ingredients can lead to irritation and inflammation.
To alleviate inflammation, discontinue all active ingredients and switch to a gentle moisturizer that retains moisture and prevents evaporation. Once inflammation subsides, you can reintroduce your active skincare ingredients gradually.
Here are the key takeaways from this guide:
1. Avoid combining retinol or retinoids with ascorbic acid. As both are potent active ingredients functioning at different pH levels, retinol thrives in higher (alkaline) pH levels, while ascorbic acid prefers acidic environments.
2. Do not mix retinol or retinoids (Vitamin A derivatives) with AHAs (alpha hydroxy acids) like glycolic acid due to the heightened risk of skin irritation, as both ingredients exfoliate the skin's outer layer.
