Let’s say that after a lifetime of searching, you finally found the holy-grail serum that gives you a natural, Fenty Beauty–level glow. But, the product seems to be losing its glowy effects now that you’re through bottle number three at the end of month six. Is this phenomenon in your head, or could the same principle behind why you should diversify your workouts (your body gets used to them) also apply to skin care? And if it’s possible that your face actually gets used to products—rendering them ineffective after a certain period of time—what can you (and I) do about it?

Check out what the experts had to say about skin-care fatigue.

Certain ingredients can become less effective over time

Charlotte Cho, co-founder and curator of Korean beauty mecca Soko Glam says that it is possible for the ingredients in your skin-care products to become weaker over time through tachyphylaxis, which is when a product loses its efficacy over time as your skin adjusts to it. Though tachyphylaxis usually refers to concentrated active ingredients (elements that have been scientifically studied and proven to yield results, such as retinol and salicylic acid), the term can also be applied to creams and other products to which your skin stops responding over time.

Maryam Zamani, MD, and founder of MZ Skin, adds that it’s possible to assume a product isn’t working when you stop seeing changes from it, when in reality, this just means that it’s working really well. “Your skin can become less sensitive to certain products with continued use, so side effects become less problematic with time,” she says. So let’s say, for example, you’re using a retinol product. Since your skin might build up a tolerance to the retinol, the absence of certain side effects could blind you to how well the product actually is working—think of this state as maintenance or upkeep. However, if you stop using a product for a period of time and then return to it, you might see it begin “work” again, Dr. Zamani says, which might be due to original issues resurfacing that the product can then re-treat.

Here’s what you should switch up—and when

Generally, experts say if it isn’t broken, don’t fix it: If your serum still gives you glowing skin and your moisturizer still keeps your skin supple, then you have no reason to swap them out. However, you should consider a change when your products no longer seem to work as well as they once did, or if after about a month of using a product, it hasn’t upheld its promises of banished breakouts, cleaner pores, or better hydrated skin, says Gunna Covert, co-owner and head trainer at skin-care haven Daphne Studio.

As a general rule, you should change your moisturizer and sunscreen (which you should be using year round) twice a year: once from winter to spring, and once from summer to fall, since these are the times of year when your hydration levels and sun exposure will change, Cho says. “Just like how we change our wardrobe seasonally, our skin-care products should do the same.”

“Just like how we change our wardrobe seasonally, our skin-care products should do the same” —Charlotte Cho, co-founder and curator of Soko Glam

Along these seasonal guidelines, you might change the active ingredients you’re using to target specific issues at specific times of year to get ahead of skin-care fatigue. Like, consider chemical exfoliants: In the winter, you might use a glycolic acid exfoliator while in the summer, you switch to a salicylic acid exfoliator to achieve similar pore penetration and oil-curbing results.

But, don’t overhaul your regimen at once: Dr. Zamani instructs to only change “one product at a time to be able to assess skin changes and to stick to those changes for at least four to six weeks to see the most benefit.” If you change all of your products simultaneously, it’ll be impossible to tell what is or isn’t working. 

There are ways to ensure your products work well for longer

Since your absolute favorite skin-saving elixirs might not work forever, it’s important to do whatever is in your power to extend the lifespan of their effectiveness. For example, “the bathroom isn’t the best place to store your skin-care products” Cho says, adding that “the heat and humidity from hot showers can make some products less effective, especially ones with active ingredients, like pure vitamin C.” Instead, store your products somewhere they aren’t exposed to direct sunlight or heat.

Another simple change that can help your products work better? Washing your face. “You can have top-of-the-line products in your arsenal, but it won’t matter if you’re applying them to skin that is not properly cleansed,” Covert says. In addition to cleansing properly, she says you need exfoliate semi-regularly to slough away the dead skin cells so your products can be efficiently absorbed. 

Last, Covert says that to maximize the effectiveness of your products, you should make sure you’re applying them in the correct order, which is (drumroll, please): cleanser, toner, treatment products, serum, moisturizer, and then sunscreen.

And then, of course, there’s patience: Pristine skin wasn’t built in a day, after all.

According to French girls, micellar water is the ingredient you’re missing, and according to dermatologists, you need more silk in your life.