The Common Skincare Ingredients You Shouldn't Use at the Same Time

Updated 01/31/18
Brooke Testoni

When every product in your bathroom cabinet claims to offer a different skincare benefit, it's understandable to think the more you use of each, the better the results will be. But as active ingredients like acids and retinol rise in popularity, dermatologists point out that mixing certain products could actually harm your skin.

"Alpha hydroxy acids (like glycolic acid), beta hydroxy acids (like salicylic acid), retinols, and vitamin C are some of the most common active ingredients recommended by dermatologists," Yunyoung Claire Chang, MD, of Union Square Laser Dermatology told The Huffington Post. While each is effective, using a combination of these products in the same routine can alter the potency of the ingredients or irritate skin. Below are the skincare ingredients you should never mix, according to two leading dermatologists.

Vitamin C + Retinol

"Vitamin C and retinol work optimally in different pH environments, and thus, should typically not be combined," Chang explains, noting that "vitamin C products are formulated to be at a low pH of less than 3.5, while retinol works best at a pH of 5.5 to 6."

She tells clients to avoid using these ingredients at the same time but notes it's safe if you a apply vitamin C serum in the morning and retinol cream at night. This "ensures full efficacy of both ingredients," she says.

Alpha and Beta Hydroxy Acids + Retinol

When used together, these active ingredients can cause excessive dryness, redness, and irritation. "Alpha and beta hydroxy acids are typically used to exfoliate the top layer of the skin and help improve color irregularities over time. Retinols are used to treat acne and to help improve brown spots, fine lines, and wrinkles," Chang explains.

Benzoyl Peroxide + Retinol

Using these two skincare ingredients renders them practically useless, says Melda Isaac, MD, at MI Skin Dermatology Center in Washington, D.C. "I advise patients to apply retinol in the evening and beta or alpha hydroxy acids in the morning" to ensure the products don't cancel each other out, she says. Chang also recommends avoiding products that contain retinol if you've had a chemical peel or resurfacing laser procedure.

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