While sticking to natural hair products can be tricky and isn’t always the best choice for your look, some ingredients can be outright dangerous, both for the look of your hair and for your health.

Check out some of the worst ingredients in hair products and find out why you should put in the effort to keep them out of your hair care regimen. From alcohol, that dries hair, to more dangerous chemicals that don’t do much for your hair but can prove dangerous for your health, here are the ingredients to avoid.

1. Isopropyl Alcohol

Used as in shellac and antifreeze, isopropyl alcohol can dry your hair and increase the risk of breakage. It’s even more important to avoid it if you have processed hair, since it will strip away all the oils from it. It’s most commonly used in hairsprays and gels, but you can also find it in products like volumizers.

2. Propylene Glycol

Definitely one of the worst ingredients in hair products, propylene glycol can have a negative impact on your health when you’re overexposed to it. That’s a problem since it’s found in everything from shampoos and conditioners to lotions and gels. Just like isopropyl alcohol, it’s a solvent, and it can also contribute to scalp irritation.

3. Sodium Lauryl Sulfate

SLS can show up on your hair products ingredients list under a lot of names, from Aquarex methyl to ammonium laurel sulfate. It’s mostly found in shampoos and industrial detergents. It can strip away oils and moisture incredibly well, which is why it doesn’t belong in your hair products. Make sure that your shampoo is SLS free if you want your hair to look and feel healthy.

Dangerous Ingredients In Cosmetic Products

4. Polyethylene Glycol

Also knows as PEG, polyethylene glycol is definitely one of the worst ingredients in hair products. Just like SLS, it’s used for cleaning industrial machines, including ovens with a lot of grease buildup. You’ll also find it in many kitchen cleaning products, so this harsh chemical has no place in your hair care routine.

5. Coal Tar

If you’re using a shampoo that fights dandruff, you should always make sure that it doesn’t include coal tar. Even though it’s a known carcinogen, it still shows up in many shampoo, under names like polytar and clinitar. You should be particularly careful about avoiding it if you suffer from allergies or asthma, since it can make those conditions worse when overused.

6. Diethanolamine, Momoethnanolamine and Triethanolamine

DEA, MEA, TEA are some of the worst ingredients in hair products because they can disrupt the natural production of hormones and can also contribute to the formation of nitrates and nitrosamines that can increase the risk of developing cancer. You’ll find them in many products that foam, so read your shampoo  labels carefully and make sure they don’t include their initials.

7. Aminomethyl Propanol

A pH adjuster found in many hair products, from hair dye to straighteners, aminomethyl propanol is safe when it’s used at levels of concentration under 2%. Higher than that, it can become toxic, and a lot of hair products use more than safe levels of this chemical.

See also: 10 Worst Pore-Clogging Ingredients

8. Formaldehyde Donors

Some of the worst ingredients in hair products can release formaldehyde. Ureas are formaldehyde donors, particularly imidazolidinyl urea, and DMDM hydantoin is another ingredient that you should avoid in your hair products. Formaldehyde can weaken the immune system and cause a wide variety of problems, from chronic fatigue to headaches and allergies.

Toxic Shampoo Ingredients

9. Mineral Oil

Made from crude oil, mineral oil isn’t toxic, but it’s still bad for your hair, particularly if it gets on your scalp. It coats your hair and skin like plastic wrap, not allowing them to breathe, which can lead to plenty of problems.

10. Synthetic Colors and Fragrances

Some of the worst ingredients in hair products are synthetic compounds used as artificial colors and fragrances. Many color pigments are derived from coal tar, which can have a negative impact on your health, and fragrances can hide hundreds or even thousands of chemicals that can cause rashes, allergies and other health issues.