The common causes of acid reflux after breakfast are gastritis, peptic ulcer, reflux esophagitis, and occupational lesions. 1. Gastritis: Gastritis is a chronic inflammation of the gastric mucosa caused by a variety of causes, such as Helicobacter pylori infection, autoimmunity and so on. Patients will have vague pain in the stomach after eating breakfast, acid reflux, nausea, some patients will have loss of appetite, tongue inflammation, diarrhea and other symptoms. 2. Peptic ulcer: Peptic ulcer is mostly related to Helicobacter pylori infection. Patients may experience vague pain in the stomach after eating breakfast, weight loss, and may also experience nausea, vomiting, regurgitation and other symptoms. 3. Reflux esophagitis: Acid reflux and heartburn symptoms are mostly seen in patients with GERD, mainly due to the acidic gastric contents, including gastric acid, backing up into the esophagus through the cardia, which causes patients to experience reflux-related symptoms. Eating high-fat, high-protein foods or being overfed, as well as being overweight due to lack of exercise, are all risk factors for the occurrence of these reflux symptoms. 4. Occupational lesions: when the tumor cells in the stomach invade the gastric mucosa, it will lead to the decrease of peristaltic function of the stomach as well as the damage of the mucosa, and then there will be an obvious increase in the secretion of gastric acid leading to a series of manifestations such as acid reflux, heartburn, and abdominal pain, etc. Patients with acid reflux need to pay attention to the symptoms of acid reflux. Patients with acid reflux need to pay attention, and it is recommended to consult a doctor in time, under the guidance of the doctor to clarify the cause of the disease and systematic treatment.