Left side of the tongue pain affects the speech may be caused by oral ulcers, burning mouth syndrome, tumors and so on. 1. Mouth ulcers: recurrent mouth ulcers often occur on the lateral edge of the tongue, or trauma-induced ulcers also often occur on the lateral edge of the tongue, which can cause pain, and in severe cases, affect normal speech. This condition requires the use of anti-inflammatory drugs such as tinidazole tablets and levofloxacin hydrochloride capsules under the guidance of a doctor, as well as vitamin B2 as an adjunctive therapy. 2. Burning Mouth Syndrome: Burning Mouth Syndrome can also occur on the left side of the tongue, which is mainly characterized by burning pain in the tongue, aggravated by the pain when speaking, and alleviated or disappeared when working, eating, sleeping or walking. This disease needs to find out the cause of the disease and symptomatic treatment, can also add artificial saliva to help speak or chew. 3. Tumor: Tumor occurring on the side of the tongue can cause pain, numbness and limited movement of the tongue, which can also affect speech. In this case, timely surgery is needed to remove the tumor, and pathological slides are examined to clarify the benign or malignant nature. It is recommended that after the left side of the tongue pain affects the speech, we should consult the doctor in time to find out the specific cause and treat it according to the doctor’s instruction, so as to avoid delaying the condition.