Bitter mouth, acid reflux and bad breath may be caused by improper diet, chronic gastritis and other factors, which can be relieved by changing diet or using medication under the guidance of a doctor. 1. Improper diet: Eating too cold, stimulating food or overeating for a long time may lead to food stagnation and indigestion. The symptoms can be relieved by eating a light diet with plenty of vitamins and proteins. 2. Chronic gastritis: usually due to Helicobacter pylori infection and other factors, chronic gastritis will lead to damage to the gastric mucosa, resulting in slow peristalsis, the accumulation of food in the stomach can not be discharged, after a long time of fermentation, there may be a bitter taste in the mouth, acid reflux halitosis phenomenon. Omeprazole, lansoprazole and other drugs can be used for treatment as prescribed by the doctor. It is recommended to pay attention to keeping the oral cavity clean in daily life and to consult a doctor in time in order to avoid delaying the condition.