Acne can be caused by products that, when applied to the skin, block pores and and result in a buildup of dead skin and sebum (the body’s natural oil) beneath the surface. This impaction of the pore is called a comedo, so you may have seen the term comedogenic on skincare product labels. This refers to the products’ tendency to cause acne.

Certain ingredients in oils and fragrances are more comedogenic than others and a rating scale of 0-5 is used to express their tendency to cause blockages. It’s better to read the ingredient list of a product to check for the presence of the comedogenic chemicals rather than rely on the product labels. Of course, the closer to the top of the list, the more of that ingredient the product contains, but it’s also possible that other ingredients could cause acne when formulated together, so you have to actually use a product to really know how your skin will react.

Here are a few level 5 ingredients (maximum pore clogging capacity) to check for on product label (and avoid!):

  • Isopropyl isostearate – A natural liquid ester made from isopropyl alcohol and stearic acid. Used as a lubricant, it also acts as a binding agent, holding the oils tightly together in your pores.
  • Isopropyl myristate – Another natural ester, this time made from isopropyl alcohol and myristic, a fatty acid found in foods. It is a moisturizer, skin softener and binder that will clog poor and bind oil with skin cells.
  • Myristyl myristate – An occlusive skin conditioner. It helps the product to spread better and seem creamier/smoother.
  • Laureth-4 – A surfactant and emulsifying agent. It can irritate the skin and cause increased production of sebum from the body.
  • Oleth-3 – An alcohol that is extremely powerful and can continue to block pores even when diluted down to a 5% concentration.

Also be careful with these ingredients that often rate a 4 on the comedogenic scale:

  • Coconut butter/oil
  • Acetylated lanolin
  • Acetylated lanolin alcohol
  • Lauric acid
  • Isopropyl palmitate
  • Isostearyl isostearate
  • Myristyl lactate
  • Stearyl heptanoate
  • Cetearyl alcohol + ceteareth 20
  • Cocoa butter

By being aware of what’s in your skincare products, you’ll reap the positive benefits, while avoiding breakouts. And remember: Everyone’s skin is different. What may work for a friend, may not work for you.