Redness, swelling and pain in the mouth are commonly caused by periodontal inflammation, oral ulcers, herpes and so on. It is recommended to correspond to periodontal treatment or medication after clarifying the cause of the disease. 1. Periodontal inflammation. Redness, swelling and pain in the mouth may be caused by long-term stimulation of tartar and bacteria causing periodontal inflammation, red, swollen, bleeding and painful gums, periodontal treatment is needed for recovery, such as gingival cleaning, subgingival scraping to remove tartar and plaque, and periodontal flap surgery to scrape out hidden tartar if necessary. 2. Root canal treatment. Oral redness, swelling and pain may also be apical periodontitis, the bacteria inside the tooth invade the periapical tissues triggering pain, the teeth do not dare to bite, usually root canal treatment to remove the causative factors to relieve pain. 3. Mouth ulcers, herpes. When oral ulcers or localized herpes, the oral mucosa will also appear red, swollen and painful, usually use cediriodine tablets to treat oral ulcers, ribavirin and other antiviral drugs to treat herpes. The redness, swelling and pain in the mouth may also be caused by trauma, which needs to be determined after checking the oral cavity in the hospital. Drugs should be used under the guidance of a doctor.