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The Dos and Don'ts

when it comes to mixing skin care ingredients!

Lately I have been receiving tons of questions about skin care products and their ingredients. I found that even Dermatologist have been prescribing ingredients that should never be mixed together as part of their patients skin care routine. For example, Benzoyl Peroxide mixed with Tretinoin (retinol) or Vitamin C mixed with Niacinamide. NO! NO! NO! And OTC ingredients are not equal to medical-grade ingredients.

Not all skin care ingredients, though potent and effective on their own, work well together, and using them at the same time could be putting your skin on a never-ending loop of reaction, solution and repeat. Mixing ingredients without proper knowledge of how these ingredients work and what other ingredients they may interact with will be not only a waste of money, but also time. It can also lead to frustration if less than expected results are seen (or if the skin becomes irritated).

Whether you are new to skin care or maybe you've just decided it's time to take your routine to the next level with more than just a simple cleanser and moisturizer! Either way, you have probably read some online reviews, stocked up on products that best cater to your skins needs, and now you just need to figure out whether the ingredients in all of these creams, serums, and masks work harmoniously.

Now lets take a look at some of the most important ingredients that you can have in your skin care routine and their purpose. Lets also talk about when is the best time to apply each ingredient and some Do's and Don'ts when it comes to mixing certain ingredients.

Also known as vitamin A, what makes retinol so great is that it promotes skin cell turnover, which can help improve the appearance of fine lines, wrinkles, uneven skin texture, dark spots, and acne. This product is best applied at night for it's sensitivity to UV and because our skin cells do their repair work most effectively at night. Research shows that skin cell regeneration almost doubles at night! BUT, Retinol can be very irritating and can exacerbate skin dryness, without proper care.

DO: mix with moisturizing ingredients like Hyaluronic Acid and ceramides.

DONT: mix with Vitamin C, Benzoyl Peroxide and AHA/BHA acids.

This will increase skin irritation and benzoyl peroxide may reduce the effectiveness of tretinoin (Vitamin A derivative).

Vitamin C is like your insurance! It protects the skin from oxidative free radical damage and works best in the morning like your morning juice of OJ. This ingredient not only protects your new cells but it also brightens, lightens dark spots and works synergistically together with Retinol after weeks of consistent use to change the DNA in our cells!

DO: mix with antioxidants (especially Vitamin E) and SPF.

DONT: mix with retinol or Niacinamide.

Niacinamide and Vitamin C potency is significantly diminished when used together, unless application is spaced by at least 10 minutes between each serum.


Also known as vitamin B3, this antioxidant is an anti-inflammatory that can brighten skin and even out discoloration. Great for those who suffer from acne and acne scarring. Niacinamide can be applied twice a day or once a day.

DO: mix with ALMOST every ingredient.

DONT: mix with Vitamin C

The two can cancel each other out when applied together unless layering between a 10 minute wait time between the two.

Benzoyl Peroxide

If you suffer from Acne vulgaris this ingredient can be a total GAMECHANGER! If you want to minimize any chance of an interaction if you are using tretinoin, apply the tretinoin-containing formulation in the PM, and use your benzoyl peroxide in the AM, or use a wash-off benzoyl peroxide cleanser rather than applying a leave-on benzoyl peroxide.

DO: Benzoyl Peroxide with gentle hydrating ingredients, SPF, and topical antibiotics.

Try mixing with moisturizing ingredients that can buffer the dehydrating effects of benzoyl peroxide, it be used in conjunction with prescription topical treatments like clindamycin! SPF should also be worn every day!!

DONT: Benzoyl peroxide with retinol

Remember to use acne prescription tretinoin with caution.

This is the most commonly misused product that I see in my treatment room almost daily! You NEVER want to mix your sunscreen with your makeup or moisturizer. Sunscreen should be applied as a single layer to preserve the protection factors! I know it's just one more step in an already lengthy skin care routine but you don't want to skip this most important step in your skin care routine every morning. It's the only way to effectively protect skin from cancer and environmental aggressors, which can lead to premature signs of aging. Make SPF your new best friend!

DO: SPF can (and should) be used in any and every skincare routine

DONT: mix SPF with makeup or moisturizers

SPF can be layered over any skincare ingredient. No shortcuts on this one!

If you found this information to be useful please give it a "like" and if you have any recommendations please feel free to leave a comment!

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