Why Preservatives Are Necessary In Solid Hair Care

OG Shampoo and conditioner bar with preservatives

Key Takeaways:

  • Preservatives in personal care products and cosmetics are used to prevent the growth of bacteria and microbes that could be harmful to our health.
  • They’re necessary, but some synthetic preservatives on the market have been linked with human health concerns.
  • At Solid Roots, we go the extra mile to select preservatives that are natural and plant-based, but also very safe and effective. 

I was at a market this past weekend and someone was asking me about what kind of preservative we use in our shampoo and conditioner bars. She was struggling with some allergies affecting her skin which she was pretty sure were caused by some of the synthetic preservatives that are used in traditional shampoo and conditioner. She had been trying loads of different brands in the hopes of finding something that didn’t bother her skin. 

Preservatives in personal care products and cosmetics are used to prevent the growth of bacteria and microbes that could be harmful to our health. They also serve to increase the shelf-life of the product. Basically, they’re pretty bad-ass at making sure the products we are putting on our skin and hair are safe to use and can last a long time (even if we abuse them by leaving them in a hot car on a North Carolina summer day. Guilty!)

The topic of preservatives is very controversial in the world of personal care products, and for good reason. A few bad actors have been linked with some not so great health outcomes, which has caused quite a scare. One of the most well-known and potentially harmful groups of preservatives are known as parabens (notice I said potentially harmful. More on that later.) Some common parabens include methylparaben, propylparaben, butylparaben, and ethylparaben. These preservatives are very effective at preventing harmful microorganisms from colonizing your lotion and turning it into moldy goop, but some studies have suggested that they also have the potential to disrupt your hormonal system as they are structurally similar to estrogen. But, scientists are just scratching the surface on this and much more work needs to be done before we should totally vilify this broad group of preservatives.

Most preservatives used today are very safe and there are loads of studies and reports known as Cosmetic Ingredient Reviews that back up this claim. A preservative is needed anytime a product is made with water (such as a liquid shampoo…containing up to 90% water, I might add!) For example, if you made up a batch of shampoo with just your cleansing agents, fancy botanical extracts and water, you would have a moldy bottle of shampoo in about a week if left at room temperature (longer if kept in the fridge). Bacteria, yeast, and mold are able to grow anytime there is water present. So, any product that contains water – shampoos, conditioners, lotions or serums, to name a few – needs to have a preservative. On the flip side, certain products, such as body butters only made with butters and oils don’t need a preservative. Traditional soaps are also preservative-free because the pH is too high to allow the growth of any bacteria or mold.

But, what about lovely, pH-balanced shampoo bars? They’re solid (i.e. waterless) so they should be fine without a preservative, right? Not quite. Most solid shampoo and conditioner bar formulations do have a tiny bit of water in them from some of the liquid ingredients that are used. So while they typically DON’T contain enough water to allow bacterial growth, they DO get wet every time you shower or bathe which increases the chances that microbes could grow. 

I have seen the ingredients list of other shampoo bars on the market that don’t use a preservative and, to be honest, that makes me a little nervous. The bars are likely fine if just used under normal circumstances, like for your daily shower, but what about if someone travels with them or takes them to the gym and they’re left in a closed container without proper airflow for days at a time? Not a risk I’m willing to take. I like you and want to keep you safe! 

At Solid Roots, we go the extra mile to select preservatives that are natural and plant-based, but also very safe and effective. For example, the preservative that we use in our solid shampoo bars is an extract from the American aspen tree. This preservative is effective against many types of bacteria as well as yeast and mold. Additionally, it’s been suggested to help soothe the scalp instead of irritating it. 

In our conditioner bars, we use an extract from the elderberry plant, which is also rich in a variety of phytonutrients exhibiting both antioxidant and anti-inflammatory properties. For both our shampoo and conditioner bars, just to be extra-safe, we also double up on the yeast protection, since your bars are sitting in a humid environment in your bathroom. Our extra protection is from potassium sorbate (the natural salt of sorbic acid), which is safely used to protect many food products, such as cheese, baked goods, and wine and has loads of safety data backing it. It’s also used quite often as a preservative in other water-containing personal care products, though it’s not quite strong enough to use on its own.

While I don’t have the scientific data to back this up, I’ve heard stories from many happy customers that our solid bars irritate their scalps less than traditional shampoo and conditioner. Could it be from our choice of preservatives?