The causes of itchy mouth include infection, allergy, mosquito bites and so on. If people have itchy lips for a long time without any improvement, it is recommended to go to the hospital for examination, to clarify the cause of the disease, and to treat the cause. 1. Infectious factors: due to certain bacterial infections, can cause lipitis, causing itchy lips and mouth, and in severe cases, there are painful symptoms. In addition, when people suffer from viral herpes, blisters will appear around the lips and mouth, causing pain, itching and other uncomfortable symptoms. When people are infected, it is recommended that they be treated under the guidance of a doctor. 2. Allergic factors: when contacting certain substances that will cause one’s own allergy (such as food, cosmetics, etc.), or due to strong ultraviolet radiation, it will lead to contact dermatitis, causing itchy lips and mouth. Allergen testing should be carried out under the guidance of a doctor to keep away from allergens or to carry out desensitization treatment. 3. Mosquito bites: mosquito bites on the lips and mouth, can also trigger itching. If the mouth is itchy for a long time, or accompanied by other discomforts, you should consult a doctor in time and follow the doctor’s instructions for treatment.