Ulcers on the side of the tongue need to be alert to vitamin deficiencies, traumatic ulcers, infections, and tongue cancer. 1. Vitamin deficiency: If there is a lack of vitamin B12 or trace elements, the body’s autoimmunity may be lowered, which may lead to the phenomenon of ulcers on the side of the tongue. 2. Traumatic ulcers: mainly caused by traumas such as sharp tips of premolar teeth, stumps or biting the tongue. 3. Infection: such as bacterial and fungal infections cause erosion and ulceration of oral mucosa, which can also be manifested as ulcers on the side of tongue. 4. Tongue cancer: long-term tongue ulcers need to be alerted to tongue ulcers caused by tongue cancer if there are hardness and lumps in the affected area. If the symptoms of lateral tongue ulcer appear for a long time, you should go to regular hospital in time to find out the cause of the ulcer and treat it actively so as to avoid delaying the condition.