Mouth ulcers, if accompanied by secondary infection, can be treated with antibacterial drugs systemically, such as taking artificial oxalic metronidazole capsules. Artificial oxalic acid metronidazole capsule main ingredient is metronidazole and artificial oxalic acid, with anti-inflammatory and antibacterial effect. Common adverse reactions are gastrointestinal reactions, such as nausea, loss of appetite, vomiting, diarrhea, abdominal discomfort, altered sense of taste, dry mouth, metallic taste in the mouth. It is contraindicated in allergy, pregnant women, and alcohol drinkers. Mouth ulcers without secondary infection are usually treated locally without antibiotics. However, if it is accompanied by secondary infection, it can be treated with antibiotics systemically, such as taking artificial oxalic metronidazole capsules. But the use of medication should be used under the guidance of a doctor.