Brushing your teeth is a must for maintaining good oral hygiene, but did you know there are times when you should avoid reaching for your toothbrush? A recent TikTok video by Dr. Shaadi Manouchehri, a London-based dentist, has shocked viewers about when brushing your teeth might do more harm than good, Today reported.

There are three specific situations when you should refrain from brushing your teeth, according to Manouchehri: after vomiting, after eating breakfast and after sweets. While these may seem like prime times to clean your pearly whites, she explains why, in fact, they are not.

When you vomit, eat breakfast or indulge in sugary treats, the bacteria in your mouth metabolize the food particles and produce acid as a byproduct, Manouchehri said. This acid can temporarily soften and weaken your tooth enamel, which is composed primarily of minerals. Brushing your teeth immediately after is like “basically rubbing the acid onto your teeth, which can damage them,” she explained.

The acidity in the mouth will naturally neutralize over time — but that time period can take roughly 30-60 minutes for the salivary buffers to act, she said.

Dr. Tien Jiang, an assistant professor at Harvard School of Dental Medicine, agrees with Manouchehri’s advice. Jiang explained to Today that while many people associate cavities with sugar consumption, it’s actually the acid that can remove the minerals from the tooth’s enamel.

This acid can come from various sources, including vomit, carbonated drinks and even citrus fruits. “To protect your teeth, don’t brush them right after having food or drinks that contain a lot of acids. Examples include soft drinks, such as soda and sports drinks, sour candies, citrus juices and citrus fruits,” according to the Mayo Clinic.

So, what should you do if you find yourself in one of these situations? Manouchehri recommends waiting 30-60 minutes before brushing your teeth. In the meantime, she recommends to rinse your mouth with water or chew sugar free gum to help neutralize the acid quicker.