It’s important that every professional hair stylist is well acquainted with different types of shampoos and shampoo ingredients. You want to personalize your service and use the right formula on each client so they look and feel great when they walk out your salon door. You also want to give them good, informed advice regarding what to lather up with at home.

Of course, that’s why you know things like that shampoos containing sulfates—a common component in shampoos—can fade hair coloring. It’s also helpful to know which ingredients can exacerbate dry hair and scalp and hair loss, as well as which ones can cause irritation, may pose long-term health risks, or cause other problems.

Here are some common, potentially harmful shampoo ingredients to be aware of. It’s not that they all need to be eliminated from your work station and shelves. But, you should know which ingredients to steer clear of for clients with particular issues, and in general, the more you can avoid them, the better.


Potentially Harmful Shampoo Ingredients

  • Parabens – Used to prevent bacterial growth in shampoo and other products, this preservative is known to mimic estrogen and cause accelerated growth of certain types of breast cancer. Recently, many manufacturers have stopped using parabens, but they’re still fairly common.
  • Ammonium lauryl sulfate or sodium laureth sulfate (SLES) – These cleansing agents bind with water and natural oils on the scalp and hair, removing them when rinsed away. This can make these ingredients drying, irritating, and damaging—especially for people with existing dry head conditions—and they can also increase brittleness and frizz.
  • Sodium lauryl sulfate (SLS) – This shampoo foaming agent strips moisture and sebum from the scalp and hair, having the same possible effects as described in the previous entry. It also fades color.
  • Formaldehyde – A familiar and common preservative, formaldehyde is known to increase the risk of certain cancers in humans. The tricky part is that it’s not always added on its own; some other preservatives, like quaternium-15, release it gradually over time.
  • Triclosan – Even though this antibacterial agent was banned from use in soaps, it’s still allowed in shampoos (as well as toothpastes and deodorants). It’s known to cause hormone disruptions that can pose risks related to cancers, fetal development in pregnant women, and other health problems.
  • Sodium chloride – Also known as salt, this is one of those potentially harmful shampoo ingredients many people overlook. It’s added to conditioners and shampoos as a thickener, but it’s irritating to some people and can cause considerable itching—and with it, scratching and maybe even increased hair loss in people already experiencing it.
  • Polyethylene glycol (PEG) – Another thickening agent, this one doesn’t really have conclusive scientific evidence that it’s harmful in and of itself. But it’s made from petroleum, which is very often contaminated with other compounds that are well known to pose health risks to humans.
  • Diethanolamine (DEA) and Triethanolamine (TEA) – These ingredients help blend the water- and oil-soluble components in shampoo and increase lather. They too don’t have hard data establishing risk in humans. However, topical applications have been tied to increased risk of cancer in animals, and the European Commission banned their use in cosmetics.
  • Alcohols with “prop” in their name – Alcohol can be quite drying on the hair and scalp—generally when it’s a form with “prop” in its name, like propanol and isopropyl alcohol. Alternatively, others without “prop” in their name, like stearyl and cetearyl alcohol, can help retain hydration.
  • Synthetic colors and fragrances – These can include all sorts of potentially harmful shampoo ingredients that may be drying and damaging, trigger itching or other irritation, increase the risk of certain cancers, or cause other undesirable effects. Artificial colors usually show up on the label as FD&C or D&C followed by a number.
  • Dimethicone – A form of silicone, dimethicone can clog pores and cause cleansing and styling products to build up on the hair and scalp. Products containing this ingredient should be used minimally, and are better avoided altogether by clients with acne concerns. Buildup can usually be addressed by using a quality clarifier.
  • Retinyl palmitate – This ingredient causes skin irritation in some people. Side effects may include redness, drying, peeling, itching, and scaling.

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