Salivary gland stones, salivary gland inflammation, salivary gland tumors, etc. may be the cause of the swelling under the tongue. 1. Salivary gland stones: Salivary gland stones, especially those in the submandibular gland, may manifest as a feeling of distension under the tongue, especially when there is a lot of saliva production. 2. Salivary gland inflammation: Salivary gland inflammation is commonly known as submandibular gland inflammation, which may be characterized by redness, swelling and pus overflow at the mouth of the salivary gland ducts, and may be felt as swelling under the tongue. 3. Salivary gland tumor: benign or malignant salivary gland tumors may also cause sublingual sensation. There may also be other pathological factors, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of the doctor.