To determine whether you have bad breath, you can try the following methods: 1. Bend the palms of your hands in front of your mouth about 3cm, and breathe out into your palms. Then smell the gas in your hand, if the gas has a foul smell, it proves that you have bad breath. 2, you can use dental floss to clean the gaps in your teeth, and then try to smell the floss. If the floss has a bad smell, it proves that there is bad breath. 3, you can also ask your family members to smell their mouth, and if there is a bad smell in the mouth, it proves that there is bad breath. If you can’t tell if you have bad breath, you can also go to the hospital dentistry department for examination. For patients with bad breath, a large reason is due to oral diseases, it is recommended that treatment be carried out as soon as possible. In addition, it is important to develop good hygiene habits and brush your teeth and rinse your mouth on time.