A British dentist has gone viral for her TikTok video explaining dental hygiene; among the points that she made: you shouldn’t use mouthwash after you brush your teeth.

Anna Peterson shared a number of tips in a clip, where she mentioned that “Using mouthwash after brushing your teeth is going to give you tooth decay, so stop doing it.”

Many of her followers wanted her to elaborate on this point. So she posted a new video to specifically discuss what the issue with post-brushing mouthwash rinsing is.

She explained that toothpaste has more fluoride than mouthwash does. Mouthwash, she says, has “a much lower concentration and it’s not enough to protect your teeth from sugars that you eat and drink.

“So when you brush your teeth, and you rinse with mouthwash straight away – you just rinse off all the high concentration fluoride, for a low concentration fluoride.”

She added, “And by no means am I against mouthwash. Because I do actually recommend it to my patients. But not every patient needs it. I certainly don’t tell them to use it after brushing.”

Her recommendation: “Choose a different time to use mouthwash, such as after lunch.” And also: “Don’t eat or drink for 30 minutes after using a fluoride mouthwash.”

One follower asked: “I floss, then mouthwash, then brush. Does that work?”

“Yes,” she answered. “That is fine to do, mouthwash is best to be used after you eat, but no harm doing it this way.”

Elaborating in a third video, Anna explained: “Mouthwash is a fantastic product to use but you have to use it at the right time of day… So you’ll wake up in the morning, you’ll floss your teeth, brush your teeth and then you’ll go and have breakfast. And pretty much anything you’re going to eat will contain sugars of some sort.

“And what happens when you eat sugars, is that your mouth becomes acidic. So it drops in PH… If the PH in your mouth drops below 5.5, it begins what is called an ‘acid attack’. If you brush your teeth at this moment, you will effectively be brushing acid into your tooth, and this causes tooth erosion. And that is why you should use mouthwash.”

In conclusion, using mouthwash before you brush your teeth is ok. Using it after you eat is probably better.