You probably don’t realize that when you use your beauty products, you’re making some obvious mistakes that could be dangerous.

Sydney-based beauty scientist Hannah English has pointed out some “beauty red flags” that she sees women do all the time.

Some of them will make you uncomfortable, especially if you think that “preservative-free” skincare is better for you.

She went to Instagram to talk about her five red flags. She asked other people on social media not to “get mad” at her for some of the things she said, which could be seen as controversial.

It’s easy to think that “natural” is better when it comes to beauty, but Hannah said, “When it comes to make-up and skin care, natural is not always better.”

“I’d never think that not having any preservatives was a good thing.

“Preservatives are in your products so they don’t get moldy, and […] we’re trying to keep that from happening so we don’t get rashes and a lot of other bad things.

“Mold will grow in a water-based product that doesn’t have a way to keep it from going bad.”

Hannah said in the video that she hates loofahs because they can grow mold if they’re not washed well, and it’s easy to think that they’re clean just because they’re in your shower and you use them to wash.

Hannah also said that even if your makeup has SPF in it, you still need to use SPF before you put it on.

She said that you would need a quarter of a teaspoon of foundation to cover your face well, and “no one uses that much foundation.”

She told you not to spray perfume on your chest and neck because it has “compounds” that can “make your skin more sensitive to the sun.”

She suggested instead that you spray it on the back of your neck, saying that it “lasts longer” that way.

Hannah also said that you shouldn’t mix sunscreen with anything else, like a tint, because it might not cover as well if you do. Adding tint, bronzer, or highlighter could make everything “unstable.”

In the comments, many people liked and agreed with Hannah’s straight-forward advice.

One person also didn’t like loofahs and wrote: “I went to a friend’s house, and in their shower, their loofah was on the floor. Not me being a guest and then telling them how to take care of themselves in the shower.”

“I had no idea that was true about perfumes. I’ll have to remember this “, someone else said.

“Taking notes,” said someone else.

“Loofahs with mold and skin care? No, thanks “, followed by clapping emojis, wrote one Instagram user.