In the world of 10-step routines and medicine cabinets stocked with dozens of skincare products filling our Instagram feeds, our nightly regimes have never been more in depth. AHAs, BHAs, vitamin C, retinol, acids, oils—by the time we go to bed every night, we’re layers deep in our never-ending quest for great skin.
But unfortunately, mindlessly slathering on products won’t always give us the results we’re looking for—some combinations of popular skincare ingredients can do more harm than good by potentially causing breakouts, dryness, and other irritations.
Before you add a new product to your routine, make sure it won’t have a negative reaction with another one of the products you use. And before you play scientist and mix powerful ingredients, be aware of these product combinations to avoid and know how you should use them instead:
Vitamin C + Retinol
The ingredients in each of these have different purposes (vitamin C’s pH level is lower), which can work against each other and cause irritations. Dr. Rachel Maiman, a board-certified dermatologist, explained that because vitamin C is an antioxidant, it’s best used in the mornings, while retinol, being photosensitive, is best used at night. That way, retinol can work overtime while you sleep, and vitamin C can give you antioxidant protection when you wake up.
Vitamin C + AHAs/BHAs
Although vitamin C is labeled as a vitamin, it still is technically an acid (L-ascorbic), and combining two acidic ingredients can lead to irritations like peeling and dryness. It can also cause vitamin C’s low pH to be altered, leading to redness and inflammation.
A good rule of thumb is to use acids like AHAs/BHAs at night since they can make your skin more susceptible to sunburn if used in the morning. Again, using vitamin C in the morning can give added benefits to the skin.
Retinol + AHAs
Adding retinol after acidic skincare can increase dryness and lead to extra irritation. If retinol is a part of your everyday routine, skip out on it on days you use AHAs. But this doesn’t mean you can’t have both in your routine. Dr. Maiman recommended applying your AHA in the morning and retinol at night, but you should always proceed with caution and take it slow. “I always advise starting with only one, and once you are stable after a few weeks, consider adding the other.” Start by using your retinol once a week, and slowly increase your frequency. Then, add the AHA slowly as well. This also depends on what type of AHA you’re using, according to Dr. Maiman. Using a cleanser with a bit of glycolic acid vs. a 20 percent AHA/BHA treatment is very different; a cleanser is much more easily tolerated, while a high-potency AHA should only be used once or twice a week.
For fans of an intense peel without all the irritation (and the price tag), this treatment combines glycolic and lactic acid, salicylic acid, and hydrating ingredients like glycerin and hyaluronic acid for the perfect mix of exfoliating without overdrying.
Benzoyl Peroxide/ Salicylic Acid + Retinol
Benzoyl peroxide and salicylic acid are the biggest acne-fighting ingredient on the over-the-counter market, usually found in cleansers and spot treatments. Using benzoyl peroxide with retinol can lead to them deactivating each other’s potency. On the other hand, salicylic acid and retinol can cause dryness and flaking. Instead, use these acne products in the morning or on opposite nights that you use retinol.
Do use: AHAs/BHAs/Retinol + Sunscreens
While all of us should be using an SPF of 30 or higher every day, acids and acne products can make skin even more sensitive to the sun. Make sure that you use sunscreen after your moisturizer instead of before to avoid diluting the SPF.