Hello everyone! I hope you are having a good day! 🙂

Today’s post will be a little bit longer, but I thought it is necessary to clear up a few things, because some people (including me some time ago) are just not aware of processes going on in our makeup. Of course, that’s easy to ignore, since those processes happen without us seeing them. Bacterial growth in makeup, or spoilage of any kind can cause many skin problems or worsen the existing problems, such as acne. If you want to learn something new, or just read one more time about things you already know, stay with me 🙂 and continue reading. 

Regardless of whether you have sensitive skin or not, one of the biggest enemies for our skin are different kinds of bacteria that can so easily spread around, especially in our beauty cases, in our favorite beauty products. Sensitive skin is prone to irritations, and often struggles with inflammation processes. Among other causes, inflammation can be caused by infection and not only for people with sensitive skin, of course. Infections are caused by a bacterium, virus or fungus that really like to grow in makeup. Therefore, it is incredibly important to pay huge attention to expiration dates of makeup products we use. But how do we know what is the right time to say goodbye to mascara, foundation, lipstick and other products we use every day?

First, let’s face the truth: bacteria are everywhere. Some of them are good bacteria, such as those in fermented dairy products, but others might be bad, cause spoilage, or even be pathogenic. While we need some good bacteria in our lives, we want to avoid all the rest, so we don’t want them in our makeup products neither. The tricky thing about bacteria is that they are single-cell organisms and impossible to see using only human eye. When they grow, they increase in numbers (cell division), not size. That’s quite inconvenient, because it means that we can’t just take a look at our foundation and estimate the number of bacteria that are in there.

Micrograph of Staphylococcus Aureus (bacterium, a common cause of some skin infections) (source: Wikipedia)

Second, just like other forms of life, bacteria need certain conditions to grow. So, why do bacteria like our makeup? 

Bacteria like water. You might already know that water is the best solvent in the entire universe. It dissolves materials we need for life, such as sugars, salts, minerals, amino acids… But in order to provide energy and grow, bacteria need water to dissolve the food too. One closer look at the list of ingredients in your favorite makeup products will reveal the fact that water is always there.  So, we can for sure put the tick next to the water on our list of desirable conditions for bacteria.

Some of those single-cell organisms also need oxygen. Even if they don’t, simply by frequently opening the package and using your makeup, you expose the product to the air and numerous bacteria in it.

Finally, bacteria mostly like mild pH and medium temperatures. Just to remind you, pH is a value which, on the scale from 0 to 14, shows how acidic or alkaline a certain solution is. Some strains of bacteria can live in slightly more acidic, more alkaline, warmer or colder conditions, but majority of them like those values to be somewhere in between. Since we don’t boil or freeze our makeup before using it (ouch! that wouldn’t be pleasant to apply), and we like it to have its pH value at least somewhere close to neutral (I believe no one would use bleach as a cleanser), it is understandable why we should pay attention to the existence of bacteria.

pH scale and values of some common substances (source: Wikipedia)

One thing bacteria don’t like is light exposure. Unlike plants, bacteria don’t need light to grow. Light actually hinders their growth. Sounds like a good news, but is it actually so good? Once you expose your makeup to light, bacteria might not be your problem, but you will most likely have another one.

Cosmetics contain many ingredients, and more than a few of them are compounds that can decompose when exposed to UV light, and in that way form other compounds which can cause instability and separation, change of color or scent of the product. In the worst case such compounds can be even harmful – carcinogenic, irritant or toxic.

So what should we do??

We should simply take care about where to store our makeup and for how long. After this long story, I think it is quite clear that makeup should be stored in dry, cool, dark places. Unfortunately, bathroom is not one of those places. I know, I know, it is more than convenient to store everything in the bathroom, many of us put makeup on there, but it is not the best choice. For a loooong time I stored everything in the bathroom, because I simply wasn’t thinking about the fact that it might be not really the best idea I’ve ever had, but some time ago I also moved all my foundations, lipsticks, mascaras, blushes, and everything else to the bedroom. That’s already much better, as long as I don’t leave anything next to the window in direct sun.

Another important thing is to regularly clean makeup brushes. We hear that all the time – clean them at least once a week and you will prevent bacteria from growing there. That’s true, and we should do that, but I would suggest also storing them properly. Away from moisture, for sure. And although they look perfectly adorable if you just put them to some holder, in a cute jar, cup, or whatever, and place somewhere so they actually act as a nice decoration in your home, the sad truth is that in that way your brushes are exposed to the dust and air but also bacteria in it. So if possible, store them somewhere else, in some drawer or cupboard, especially if you don’t use and clean them too often.

Period After Opening symbol

Even then, if you sometimes forget to take care about mentioned things, there’s no need to panic. Cosmetics contain certain chemicals that prevent bacterial growth, and preserve products. However, after a while those preservatives are not so efficient anymore, and products expire (there is a label on each product which tells us for how long is the product “fresh”, as shown in the picture).


That doesn’t mean that we should throw away all those products which expired a day or week, even a month ago. No need to fear bacteria (well, not that much)! No, that’s just the way big companies want to earn more by making us buy new stuff all the time. That only means that we should pay more attention to the appearance and smell of those products and the influence they have on your skin. If you notice small black spots in a blush (and they were not there before) – throw it away, it doesn’t look good. It is time say goodbye if you see mold, or anything unusual on the tip of your eyeliner for example. However, you should throw away any product whenever you notice a change in smell, texture or color, regardless of the expiration date on the package. Those changes indicate that there is some (bio)chemistry going on, which is quite often not a good sign if we talk about makeup. And that can unfortunately happen even before the expiration date, depending on the storage, the way we use the product, or sometimes the way products were stored and handled even before we bought them.

If you want to help your makeup to live longer, you can disinfect it by simply spraying with ethanol (alcohol) every now and then. Alcohol will evaporate but it will keep unwanted creatures away from your beauty case at least for some time.

I hope this post was useful for you, and not too long. If you enjoyed it, let me know 🙂
Do you have any tips you’d like to share? Where do you store your makeup? Write me about your experiences and opinions.

See you in the next post! :*