Hi! Do you believe in rotating your skincare products or having different brands so your skin won't get "immune" to them? Thanks! - Kaye
Hi Kaye! This is a really good question, something that a lot of people are confused about. It may be because most of us notice lacklustre performance from our products after a few months. Sometimes, this new thing works so well that our skin has never been better, but then it peters off until you can barely see the difference. Why could this be?
There are a few factors that may contribute to this change in efficacy.
The breakdown of active ingredients. A product is not 100% the same once you open it. Active ingredients become less stable as you dip into a jar or bottle over time, even when there are preservatives. Light and air getting into the packaging may also change the formula. Which brings me to my next point!
Improper storage. Exposure of the products to light, heat, and humidity also affects the formulation! Most beauty products should NOT be stored above 31 degrees centigrade - hotter than that and they either melt, "sweat", or separate. Light is also a big factor, which is why some bottles are completely opaque or very dark.
The ideal storage conditions for skincare, makeup, and fragrances would be in a cool, dark-ish place. Don't store your products in the bathroom (due to high humidity) or in a dresser where sunlight directly shines. You should keep them in drawers or cabinets, or in a room with curtained windows. Better if there's air-conditioning! You can also keep them inside your fridge.
Change in your environment. If you travel to a cooler place or when the season is considerably less hot (like right now), your skin changes - it might become drier. When it's super hot during the summer, your skin also changes. It's different for everyone, but our skin will not be 100% the same when the temperature changes for prolonged amounts of time.
For example, when I went to Japan last spring, my skin became quite dry! During the summer the, my skin became super duper oily naman. Right now my skin is dry again (particularly the cheeks) because of the cooler weather.
Changes in your body. Hormonal changes may show up on your skin (that would be your monthly period, pregnancy, or menopause). Stress from work or school or a change in diet also affects your skin.
Et ceteris paribus - all things remaining equal - I still believe that changing out a product or two once in a while keeps my skin on its toes. I am very loyal to my facial wash and toner since their main job is to cleanse effectively, but I usually rotate serums and moisturizers. These products show the most improvement on my skin whenever I go on a new one or go back to something I've tried before. Serums in particular have higher concentrations of active ingredients, so I really notice a difference whenever I'm on a new bottle.
That's just my personal observation, however. If your skin is already thriving under your current skincare regimen, there's no reason to rotate or change anything!
Hope this helps, guys. Let me know if you rotate products, and how it's been working out for you!