Will My Skincare Products Go Bad if They’re Left in the Heat?

a skincare package placed at a house door

If you’ve ever ordered a product from Renée Rouleau Skin Care, know that it was shipped directly from our headquarters in Austin, Texas. If there’s one thing you should know about Texas, it’s that it gets HOT in the summer (and in the fall, too). In fact, it’s not uncommon for the temperature to reach triple digits. That means that the box we’re shipping may sit in a hot mail truck for hours. Depending on where you live, it may sit on a hot doorstep, too.

So, what does that mean for you? Does heat affect skincare products? If so, will a scorching summer day spoil your favorite formula? In this post, I’ll share the answer to this common question.

Does Heat Affect Skincare Products?

As someone with over 30 years of experience working as an esthetician and product formulator, I can confidently say that the answer is no. If a product has been formulated properly, heat should not affect its performance. Let me explain why.

Most Skincare Products Are Tested with Heat Exposure

When skincare products are made in a certified laboratory, chemists will do stability testing. This includes an “oven test.” During this test, a product is placed in an oven with a temperature of around 115°F at 70% humidity. The product is kept in there anywhere from six weeks to three months. The purpose is to determine whether a product can maintain stability and integrity when exposed to extreme heat.

It also helps determine the shelf life of a product by artificially aging it, creating a “time-lapse.” It tells us if a product will remain stable for a full two years and whether or not it’s normal for a formula to separate or change consistency over time. Conversely, products are also subjected to cold temperatures during stability testing to see if they can hold up to freezing temperatures.

All Renée Rouleau Skin Care products go through this stability testing. They’re exposed to heat over long periods of time to ensure safety, performance, and longevity. So, rest assured that if your skincare products get hot, they won’t spoil or lose efficacy.

Note: The oven test does not factor in UV light. If a product is exposed to UV light for a long time, and it’s housed in transparent packaging, it will most likely lose efficacy. This is because ingredients like antioxidants and UV filters (in sunscreen) tend to break down in the presence of light. I recommend storing your products in a closed cosmetic bag and keeping them out of direct sunlight.

I also recommend purchasing products that are housed in airless containers since oxygen can degrade certain active ingredients. All Renée Rouleau Skin Care serums are packaged with airless pumps to keep the ingredients fresh and effective until the very last drop!

Not All Skincare Products Are Made the Same Way

While it’s true that most products that are made in a lab are held to rigorous standards, there are some skincare products that simply aren’t made to remain stable in heat. These include “all-natural” products, small-batch products that are meant to be refrigerated and used quickly, and homemade products like those you might find on Etsy.

At the end of the day, there’s no guarantee that a product has undergone rigorous testing for extreme temperatures. Keep this in mind when you’re shopping for skincare products. You also might want to consider inquiring about this before you make a purchase. After all, I can only speak for my products, which won’t lose efficacy in hot temperatures.

Next, learn how to tell whether or not a skincare product has expired.

Disclaimer: Content found on www.ReneeRouleau.com and Blog.ReneeRouleau.com, including text, images, audio, or other formats were created for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website or blog.




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  1. HI!!
    I still have a question, I have some products from the sisley collection and they say it’s all natural! But I left it in my car and it hot overheated:(
    It smells a tiny bit off but can I still use it?

    Posted By: Chloe  | 

    • Hi Chloe, it’s hard for me to comment on other products since I am not involved in their formulation. I would reach out to Sisely’s customer support for the most accurate answer!

      Posted By: Renée Rouleau  | 

  2. PERFECT timing!!! I have been wondering about leaving products in my car…by accident of course!! : )

    Posted By: tracy  | 


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