How Long Should You Be Holding Onto Your Skin Care Products?

Skin Care


Between medical school, doing research in biology laboratories, and reviewing products for the blog, I’ve been fortunate to come across a lot of scientific information pertaining to which skin care ingredients work, how they work, etc., but primarily in the skin. But in creating the FutureDerm line of products, I have been fortunate to learn skin care from an entirely different perspective – that is, as formulations, understanding the effects of concentration, pH, temperature, and the like.

For years, skin care and cosmetics were stabilized with parabens. Despite their bad rap, parabens are one of the best preservatives out there, except for the less than 2 percent of the population who is allergic. Parabens are able to fight both bacterial and fungal species, which many of the paraben alternatives are not able to do. Interestingly enough, parabens are also natural ingredients, despite the fact most natural and organic product companies tout that they are “paraben-free.” Parabens from fruits like blueberries and strawberries are structurally and chemically absolutely no different than synthetic parabens, except you are actually eating the former! [Read more:  The Real Dangerous Source of Parabens:  Your Food?]

But Aren’t Parabens Cancer-Causing Hormone Disruptors?

We all want to do what is safe for ourselves and our families. That said, rather alarmist political groups like the Environmental Working Group often say parabens are toxic. But they cite studies that use ingredients in tens of thousands to millions of times the typical concentrations these ingredients are used in skin care and cosmetics. What’s more, the majority of experts well-versed in cosmetic science don’t even agree. According to Dr. Katie Rodan, M.D., dermatologist and co-founder of Pro-Activ and Rodan+Fields, “There is just so much misinformation all over the place. No one wants cancer from a cosmetic, like in the case of the rumors about parabens. By the way, you see parabens all over the place. Did you know you just ate a spoonful of parabens? Answers just aren’t going to be known without propagating the right information.”

Part of the problem also comes from well-meaning scientists with other areas of expertise, who do a quick meta-analysis of the plethora of research studies available, allowing the sheer volume of studies to justify their cautionary statements, such as “perhaps you want to avoid parabens to be on the safe side.” But in reality, those scientists with backgrounds in cosmetic chemistry have dove into the parabens studies head-first, and understand parabens are safe and non-toxic in the concentrations they are used in skin care and cosmetics. Really.

What are the Problems with Using Paraben Alternatives, Like Phenoxyethanol, Benzoates, or Benzoic Acid and other Organic Acids?

The biggest problem with using paraben alternatives is that they decrease the shelf life of products. Due to requests from our readers, we have started to formulate certain FutureDerm products without parabens. However, this shortens the shelf life, because parabens are effective against bacteria and fungi, whereas the rest are effective against primarily fungi.

Parabens have the best shelf life because they function like antibiotics when they meet bacteria, effectively interfering with the metabolic pathways of bacteria (Cosmetics and Toiletries, 2005) in killing them. Another system that works similarly is a combination of diazolidinyl urea, sodium benzoate, and potassium sorbate – all three together (Cosmetics and Toiletries, 2005). This potent, hard-to-find combination has been found to eradicate fungi and bacteria similar to parabens. Products with parabens should last up to 2 years.

Phenoxyethanol, a type of alcohol, is a close alternative. Like parabens, phenoxyethanol inhibits or even eliminates “challenging” species of many variations of Gram-negative and Gram-positive bacteria (Letters in Applied Microbiology, 2001). It’s also been shown to be effective against more common strains of bacteria, such as E. coli and Pseudomonas aeruginosa (Microbios, 1992). While it is somewhat drying, phenoxyethanol is less drying to a solution than pure rubbing alcohol, or ethanol (Journal of Hospital Infection, 2002). Products with phenoxyethanol should last 1-2 years.

Organic acids (benzoic acid, potassium sorbate, potassium benzoate, sorbic acid), when used alone, are the worst alternative to parabens. These organic acids interact only with the cell wall of microorganisms, which has been shown to be ineffective against certain bacterial strains (Cosmetics and Toiletries, 2005) in a manner similar to many antibiotics. By contrast, parabens will interfere with the metabolic pathways of bacteria, affecting far more microorganisms than cell wall destruction alone. It is also worth noting that adding ingredients like phenoxyethanol, benzyl alcohol, and chloroacetamide added to these organic acids also does not help to improve their efficacy against bacteria (Cosmetics and Toiletries, 2005).I personally would not keep a product containing only organic acids as preservatives for longer than 6 months, but truthfully, they should last 6 months to 1 year with regular use. I am personally skeptical they last longer than that with regular use.

Tips for Keeping Your Products Longer

The vast majority of bacteria tend to thrive in damp, warm conditions. So give your products a rest in the back of your refrigerator. Never, ever store products of any kind in the shower. Most people leave at least a shampoo, shower gel or a shaving cream in the shower, but this is the best breeding ground a bacterium could ever want. And these aren’t friendly bacteria either – species like M. avium can cause tuberculosis-like disease. There are actually more bacterial species on your shower curtain than nearly anywhere else in your home, including your toilet ( So be sure that you take the extra effort to bring your products in and out of the shower with you.

Another tip: Open and close your products quickly, and tightly cap afterwards. Light and air have varying effects on bacteria, but opening the jar can allow for other bacterial species to get in in the first place. So be sure you get in and get out of your creams rapidly!

Bottom Line

I recommend throwing your products away with organic acid preservatives (benzoic acid, potassium sorbate, potassium benzoate, sorbic acid) after 6 months to 1 year. I personally do not keep these longer than 6 months. This is because these bacterial cell wall-targeted preservatives do not protect against as many strains of bacteria as bacterial metabolism-targeted preservatives.

Products with phenoxyethanol or diazolidinyl urea, sodium benzoate, and potassium sorbate (all three in combination) should last 1 to 2 years.

Products with parabens should last up to 2 years.

Got questions? I’m sure you do! Ask me your questions, I’m here and happy to help: nicki[at]futurederm[dot]com.

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