Skincare Ingredients that should never be mixed together

It’s always easy and appealing to use multiple products simultaneously in your skincare routine. But definitely, some components definitely do not blend well with each other. One wrong active or acid mixed with another wrong active or acid can cause redness, acne, or simply ineffective products.

Whether you’re building up one product on top of another, or filling a cream with serums, this post will spell out which ones you need to steer clear of. Let’s ensure that your products can perform as advertised!

Retinoids and Alpha Hydroxy Acids (AHAs)

Retinoids, derived from vitamin A, and AHAs, like glycolic and lactic acid, are popular for their ability to promote cell turnover and enhance skin texture. Retinoids boost collagen production, improve skin elasticity, and reduce wrinkles, while AHAs exfoliate the surface of the skin, revealing smoother, brighter skin.

However, combining retinoids and AHAs is a recipe for irritation. Both ingredients stimulate cell turnover, which, when used together, can overwhelm your skin. This can lead to redness, flakiness, and even peeling. The increased exfoliation may compromise your skin’s barrier, making it more sensitive to environmental factors like UV rays and pollution.

Additionally, AHAs lower the skin's pH, making it more acidic. Retinoids work best at a specific pH (around 5.5 to 6.0), so lowering the pH with AHAs can make retinoids less effective. The end result? You may experience irritation without getting the full benefits of either product.

What to Do Instead

To avoid irritation, use retinoids and AHAs at different times of the day or on alternate nights. For instance, apply your AHA serum in the morning and your retinoid at night. Alternatively, use them on separate nights to give your skin time to adjust. Always start with a lower concentration and increase gradually as your skin builds tolerance. And don’t forget sunscreen—both retinoids and AHAs can make your skin more sensitive to the sun.

Retinoids and Vitamin C

Retinoids and vitamin C are both powerful anti-aging ingredients, but they don’t play well together. Vitamin C is a potent antioxidant that brightens the skin and protects it from environmental damage. Retinoids, on the other hand, work to reduce wrinkles and improve skin texture by increasing cell turnover.

The problem lies in the difference in pH levels. Vitamin C, particularly in its most effective form (ascorbic acid), needs a pH of 3.5 or lower to work properly. Retinoids, as mentioned earlier, prefer a pH of around 5.5-6.0. When applied together, the low pH of vitamin C can destabilize retinoids, making them less effective.

Additionally, using both retinoids and vitamin C together can be irritating, especially for sensitive skin types. The combination can lead to redness, dryness, and peeling.

What to Do Instead

To get the benefits of both ingredients without irritation, use vitamin C in the morning and retinoids at night. Vitamin C is best used in the morning because it helps neutralize free radicals from UV exposure, while retinoids are better suited for nighttime when your skin is in repair mode. Always wear sunscreen during the day, as both ingredients can increase sun sensitivity.

Niacinamide and Vitamin C

The combination of niacinamide and vitamin C has long been debated. While some older studies suggested that these two ingredients could neutralize each other, recent research shows that they can, in fact, be used together—if properly formulated.

However, when mixed together in their raw forms, niacinamide (which is more basic) and vitamin C (which is acidic) can cancel each other out. This can reduce the effectiveness of both ingredients, especially when it comes to treating issues like hyperpigmentation or uneven skin tone.

Moreover, combining niacinamide and vitamin C can destabilize the pH of your skin, leading to potential irritation, redness, or dryness, especially for those with sensitive skin.

What to Do Instead

To avoid potential irritation, it’s best to use vitamin C in the morning (followed by sunscreen to prevent oxidation) and niacinamide at night. Alternatively, you can use them on alternate days to allow each ingredient to work at its ideal pH level. Niacinamide is also great for boosting hydration and soothing inflammation, so it's a perfect nighttime ingredient.

Benzoyl Peroxide and Retinoids

Benzoyl peroxide is a common acne treatment known for its ability to kill acne-causing bacteria and reduce inflammation. Retinoids, on the other hand, are also used to treat acne by promoting skin cell turnover and preventing clogged pores. While both are effective in treating acne, using them together can cause major irritation.

Benzoyl peroxide is a strong oxidizing agent, and when combined with retinoids, it can oxidize and deactivate the retinoid, making it less effective. Moreover, both ingredients can be extremely drying, leading to redness, peeling, and flakiness when used simultaneously.

What to Do Instead

To safely incorporate both into your skincare routine, use benzoyl peroxide in the morning and retinoids at night. If your skin is particularly sensitive, you may want to alternate days. Again, sunscreen is essential, as retinoids increase your skin’s sensitivity to the sun.

Salicylic Acid and Retinoids

Salicylic acid is a beta hydroxy acid (BHA) that penetrates deep into pores, making it a great treatment for acne-prone skin. It exfoliates from within, unclogs pores, and reduces oil. Retinoids also help with acne by promoting cell turnover and reducing inflammation. However, using both together can be too harsh on the skin.

The combined exfoliating effect of salicylic acid and retinoids can lead to irritation, dryness, and redness. It can also weaken the skin barrier, making your skin more susceptible to environmental damage.

What to Do Instead

If you want to use both, apply salicylic acid in the morning and retinoids at night. Alternatively, you can alternate days to give your skin a break. Again, always wear sunscreen when using retinoids, as they can increase your risk of sunburn.

Soap-based cleansers and Vitamin C

While soap-based cleansers may seem harmless, they can raise the pH of your skin, making it more alkaline. This can be a problem when using vitamin C, which requires a low pH to be absorbed effectively. Using a high-pH soap before applying vitamin C can reduce its effectiveness and prevent it from delivering its full antioxidant benefits.

What to Do Instead

To maximize the benefits of your vitamin C serum, use a low-pH cleanser in the morning. Look for cleansers with glycolic or salicylic acid, which will help maintain the skin’s acidity and ensure that your vitamin C serum can work its magic.

Final Thoughts

When it comes to skincare, more isn’t always better. While powerful ingredients like retinoids, AHAs, and vitamin C can offer amazing benefits on their own, mixing them incorrectly can lead to irritation, reduced effectiveness, and damage to your skin barrier. The key is to understand how these ingredients work and how to incorporate them into your routine properly.

To avoid issues, try using these powerful ingredients at different times of the day or on alternate days. Always introduce new products gradually and listen to your skin, if it becomes irritated, scale back. And most importantly, don’t forget sunscreen. Many of these active ingredients increase your skin’s sensitivity to UV rays, so protecting your skin during the day is essential for maintaining a healthy, glowing complexion.