Cosmetic Ingredients You Shouldn’t Mix: A Guide to Skin Safety

In the world of skincare, choosing the right ingredients is crucial to maintaining healthy skin and achieving the best results. However, not all ingredients are compatible, and in some cases, mixing certain ones can compromise product effectiveness or even irritate your skin. Here are some cosmetic ingredients you should avoid combining.

1/14/20252 min read

1. Retinoids and Exfoliating Acids (AHA/BHA)

Retinoids (like retinol) and exfoliating acids (AHA and BHA) are both powerful ingredients, but their combination can be too harsh for the skin. Retinoids accelerate cell turnover, while acids exfoliate the skin's surface. Using them together can lead to dryness, redness, and irritation.

What to do: If you want to use both, try alternating them on different days or applying one in the morning and the other at night. Always follow with a good moisturizer.

2. Vitamin C and Niacinamide

Vitamin C (ascorbic acid) is a powerful antioxidant that helps brighten dark spots and protect the skin from environmental damage. Niacinamide (vitamin B3), on the other hand, is known for its anti-inflammatory properties and pore-reducing effects. While both are excellent ingredients, some studies suggest that using them together might reduce their effectiveness.

What to do: If you want to include both in your skincare routine, apply vitamin C in the morning and niacinamide in the evening.

3. Hyaluronic Acid and Exfoliating Acids

Hyaluronic acid is famous for its ability to retain moisture in the skin, while exfoliating acids remove dead skin cells. Although not harmful when combined, hyaluronic acid might not work as effectively if the skin is too dry or irritated from strong exfoliants.

What to do: Use a gentle exfoliant and follow it up with a serum or cream containing hyaluronic acid to ensure your skin stays well-hydrated.

4. Alcohol and Fatty Acids (Natural Oils)

Alcohol, especially denatured alcohol, is a common ingredient in toners and serums as it acts as a solvent or preservative. However, alcohol can dry out and irritate the skin. When combined with natural oils, alcohol can undermine the oils' nourishing properties, reducing their moisturizing benefits.

What to do: If you have dry or sensitive skin, opt for alcohol-free products and prioritize pure natural oils.

5. Benzoyl Peroxide and Retinoids

Benzoyl peroxide is a common ingredient in acne treatments, while retinoids are often used for acne and anti-aging. However, combining these two ingredients can be too harsh, causing irritation, dryness, and peeling.

What to do: If you’re treating acne with benzoyl peroxide, use retinoids on separate days or consult a dermatologist for a more suitable routine.

6. Exfoliating Acids and Vitamin C

As mentioned earlier, both AHA/BHA acids and vitamin C are effective ingredients, but their combination can be too irritating, especially for sensitive skin. Acids exfoliate the skin, while vitamin C, though beneficial, can cause irritation when used alongside strong exfoliants.

What to do: Alternate the use of vitamin C and exfoliating acids to reduce the risk of irritation.

Every skin type is unique, and what works for one person might not work for another. When building a skincare routine, it’s essential to pay attention to the ingredients you mix. Don’t hesitate to experiment to see how your skin reacts, and if in doubt, consult a dermatologist for personalized advice.