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Q: Is It Safe to Combine Vitamin C Products?

29 Jun 2020

With a love for cosmetics from a young age, my curiosity knew that there was much more to the goop inside the jar than meets the eye. I graduated with a Bachelor’s of Science in Analytical Chemistry and moved to California to chase my dreams of becoming a cosmetic chemist, passionate about developing results-driven skincare. Now, I am the Product Innovation Manager for Youth To The People. My primary experience is in research and development, with a focus on both sustainability and the formulation of skincare, bringing natural ingredients to the forefront of the cosmetics market. I’m here to answer all of your skincare questions.

Question: Is it safe to combine vitamin C products?

Answer: Vitamin C is a great daily use active because of its ability to interfere with UV rays and pollution. In your regimen, it should be the first active ingredient you put on your skin after cleansing, and I would also recommend that you look for it in your suncare as well as making it a part of your nightly routine. Doing so can help increase its effectiveness, allowing you to see results—including a healthy glow, reduction hyperpigmentation, and the appearance of firmer, plumper skin—more quickly. Users sometimes report sensitivity, and that usually has to do with formulation.

Commonly listed as L-ascorbic acid on an ingredients list, vitamin C is an antioxidant that targets reactive oxygen species (ROS), or chemicals that have highly reactive oxygen atoms that can easily bind with other chemicals. Examples of ROS include common pollutants such as carbon monoxide and tobacco smoke. These pollutants can cause damage to our skin on the cellular level, damaging our DNA and wreaking havoc on our skin cell’s ability to make new, healthy cells.

In order for L-ascorbic acid to be oxidatively stable, it needs to be in a medium that is either acidic (low pH) or anhydrous (waterless). With the former, it is important to make sure you are not over-exfoliating which can lead to sensitivity. 

On the other hand, anhydrous formulations typically come with a high solvents content. Ingredients like dimethyl isosorbide, propylene glycol, and denatured alcohol have the ability to help the active penetrate the stratum corneum without water, and these ingredients increase the efficacy of the active while protecting it from oxidizing and becoming less effective, but they can lead to potential sensitization when not formulated properly. With overuse, sensitization can occur because of increased transepidermal water loss, making skin feel dry and parched, even when the vitamin C is working. When using vitamin C, it is important that your regimen includes moisturizers.

To safely combine products containing vitamin C, remember to first apply the product containing the highest concentrations of vitamin C first, to clean dry skin. Pay attention to your skin and its sensitivity—moisturizers with vitamin C can be applied daily with your serums, and if you find your skin is sensitive when using both products, I recommend starting with a vitamin C-containing moisturizer, and slowly building your tolerance to a serum by incorporating it into your nightly routine. Hydration and moisturization are very important when using high concentrations of actives. Most importantly, sunscreen is going to help protect your skin and allow for those highly-concentrated antioxidant products to keep doing their work, so opt for a sunscreen with an SPF of 30 or higher.

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