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Ingredients to Avoid Combining

February 21, 2011 Reviewed by admin 10 Comments

We all want the best for our skin but when we get caught up in using a ton of different products, we may end up doing more harm than good. Always read labels and consult a dermatologist if you’re unsure about what creams and serums can be used simultaneously. In the mean time, take a look at the list below to learn about ingredients you should avoid mixing:

Retinol and Benzoyl Peroxide: These two are often prescribed to fight acne, and the former is a known anti-wrinkle ingredient. Both are also seriously powerful stuff – they can be extremely harsh on skin and drying individually, so you can imagine what combining them might do. Excessive peeling, redness and even scarring can occur, plus using the two simultaneously may actually counteract both ingredients’ effectiveness.

Copper Peptides and Vitamin C: Vitamin C is known for its ability to fight wrinkles, reduce hyperpigmentation, protect against photoaging and stimulate collagen. And copper peptides have been hailed as an even better collagen stimulator than vitamin C. But there is a persistent rumour that combining the two together may not always work. According to various beauty websites, copper peptides break down vitamin C, negating its effects and causing it to become inactive. However, my research suggestes the combining copper peptides and vitamin C is not an issue. There is evidence that the two substances would interact by vitamin C replacing the peptide as the chelating agent around the copper centre, but it is a very uncommon occurrence. Although it would somewhat depend on the relative concentrations of the two substances, the effect in an overall product would be near negligible. So while there is a shred of truth to the rumours about combining the two, it's largely overblown. 

Retinoids and Glycolic Acid:  AHAs, like glycolic acid (which is an extremely effective exfoliator), can make retinoids inactive. Definitely consider using one in the morning and one in the evening.

Sodium Benzoate and Vitamin C: When mixed with any Vitamin C ingredient, benzene can be created, and it is known that heat, light and shelf life can also affect the rate at which benzene is formed, according to Wikipedia. Benzene is considered a high hazard ingredient by the Cosmetics Database and is a known human carcinogen.

Now, what about physically combining products – like sunscreen with moisturizer or foundation, for example? Yes, it’s nice getting two steps out of the way at once, and you won’t have to deal with the potential chalkiness or greasiness that often accompanies wearing sunscreen on its own. But there’s a good chance that you’re diluting your sunscreen and affecting its photostability. Plus, sunscreen is formulated with certain ingredients for a reason, and if they interact with your moisturizer’s components, they might be rendered ineffective.

  • November 12, 2015

    by Jennifer

    I purchased a Argireline product made by Refinee called line stop. Cam I use this with my Neutrogena deep wrinkle serum and cream? They have retinol ( Neutrogena) or should I stick with cerave which contains hyaluronic acid.

  • February 23, 2014

    by Dorina

    what about Niacinamide? When i used niacinamide in the morning and glycolic at night, i had the worst skin ever. I took a break from both for 1 month and now i am using only niacinamide which gave me great skin and it seems to fade scars faster. Do you know why i had bad reaction when using it with glycolic? Thank you.

  • February 25, 2013

    by Marta

    Hi A, I think its best to use an AHA at a different time to your serums. Preferably at night since they will make your skin more sun sensitive. It shouldn't be necessary to use AHAs every day and I see from your other question (on a different post) that you using retinol as well. That's a lot of exfoliation. I would suggest either AHA or retinol at night (perhaps even just 2-3 times a week) and serums during the day.

  • February 24, 2013

    by a

    well can we use aha cream on egf serum?=and also can we usde glycolic in morning?if we can use it in morning can we use aha cream after c serum and peptide serums?also when we need to put hyalüronic acid hydra serums can they prevent their efficiency if put first?thanks

  • February 10, 2013

    by Marta

    Hi Debbie, it isn't a good idea to combine prescription retinol with other actives. Retinol is a heavy duty exfoliator and will interfere with other actives and render them less effective. At least spread out their use - retinol at night, CP in the mornings.

  • February 9, 2013

    by Debbie Herbert

    Can you combine copper peptides and retinol?

  • April 5, 2012

    by NDO

    AHA's do NOT cancel retinoids. This is a total misconception.

  • July 26, 2011

    by Skin care ingredients that don’t mix well | The Echolife Blog

    [...] – at worst, you could dry out your skin and cause burns and scarring – yikes! This article from Truth In Aging gives you a quick list of known offenders that shouldn’t be [...]

  • February 22, 2011

    by Sandy

    Thanks, SarahK. This is great. I rarely think about how my potions and lotions react with each other, and I appreciate your time for this research. Very helpful!

  • February 22, 2011

    by Elena

    Very interesting and helpful info!!! Thanks a lot!

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