Mouth ulcers belong to the category of “mouth sores” in Chinese medicine. The principle of watermelon cream for mouth ulcers is that watermelon cream can clear away heat and fire, reduce swelling and relieve pain. Watermelon Cream is composed of watermelon, nitrous oxide, saltpeter and ice chips. It is used for tonsillitis and pharyngitis caused by lung and stomach fire-heat upward steam, which is characterized by redness and pain in the throat, redness and swelling of the laryngeal nodes, sores in the mouth and tongue, swollen gums, and watery pulp. It should be noted that, taking this medicine, avoid spicy, fishy food; pregnant women are prohibited; spleen qi deficiency and cold evidence of loose stools should be used with caution; tonsillar suppuration and generalized high fever should go to the hospital; pay attention to the spraying of the drug do not inhale, in order to prevent the powder into the respiratory tract and cause choking and coughing; after 3 days of use of the drug symptoms do not improve, or the emergence of other symptoms, you should go to the hospital for medical attention. The specific medication about watermelon cream should be carried out under the guidance of a specialist, not unauthorized use of medication.