The causes of pain on the side of the tongue are as follows: First, mucosal ulcers: suffering from mucosal ulcers on the lateral edge of the tongue, it is often caused by traumatic stimulation of the lateral edge of the tongue ulcers, such as the presence of misaligned teeth in the mouth, or untreated dental caries, and relatively sharp tooth tips, often scraping and biting the mucosa of the lateral edge of the tongue, resulting in traumatic ulcers, ulcers can cause relatively severe pain. In the treatment, you can apply tretinoin oral ointment locally, or spray watermelon cream spray and other drugs for mouth ulcers to promote the healing of the local trauma. Second, lingual papillitis: If the pain on the lateral edge of the tongue is present at the root of the tongue, it is mostly caused by inflammation of the lingual papillae at the root of the tongue. It is often caused by inflammation of the tongue papillae at the root of the tongue when the body is on fire, which can easily lead to pain. In the treatment, you can use some medicine to clear heat and remove fire, in addition to pay attention to oral hygiene and maintain a balanced nutrition.