A dentist has warned people “never” to brush your teeth – in three specific circumstances. Dental surgeon and facial aesthetics practitioner Dr Shaadi Manouchehri has many followers on social media.

As well as being a dental professional, Dr Shaadi is also known for her advice on all things oral hygiene on Instagram, and in a new post Dr Shaadi said: “I’m a dentist and this is the only time you’ll catch me telling you not to brush your teeth.”

There are three instances where people should avoid picking up their toothbrushes, the dental expert said. Firstly, you should never brush your teeth after eating breakfast.

Dr Shaadi said that this is because “when you eat, an acidic environment is created in the mouth, and if you go in and brush your teeth straight away you are basically rubbing that acid onto your teeth, which are made up of minerals, and this can damage them, make them more yellow, and make them more susceptible to getting cavities.”

Another instance where you should wait a while before brushing your teeth is straight after you have vomited. While all you want to do may be to get the rancid taste out of your mouth, it can be very damaging to brush your teeth after you have been sick.

This is because, Dr Shaadi says, there is “extremely acidic” stomach acid present in vomit. She continued: “This is going to make your teeth really weakened, and susceptible to damage. If you go and brush your teeth straight away, again, you’re rubbing the acid onto the surface of your teeth.”

Thirdly and finally, people are being urged not to brush after eating sweet foods. Dr Shaadi explained: “This is a misconception because when you eat sugary things, the bacteria that are on your teeth are also going to eat that sugary thing and create an acid that is sitting on top of your teeth.

“Your saliva is naturally going to buffer that acidic environment, but it takes it some time to do that – about half an hour to 60 minutes. If you brush your teeth straight away, you’re rubbing the acid onto the teeth, making them weaker and more susceptible to decay”.