The most common reason for tongue blistering is that the tongue has mouth ulcers, and it may also be caused by diseases such as sublingual gland cysts and salivary gland mucous cysts, etc. The main reasons for tongue mouth ulcers may be fire, lack of vitamins in the body, mental stress, often staying up all night, or when there is a dental disease, the tongue repeatedly rubs against the sick teeth with a certain degree of relationship, and it may also develop into a tongue ulcer when it is accidentally bitten during normal meals. Mouth ulcers. Sublingual gland cysts often grow underneath the tongue, and the reason for their occurrence is considered to be the result of trauma or blockage of the ducts of the sublingual gland. They may also be caused by mucous cysts of the minor salivary glands, which can occur on the ventral side of the tongue or on the lower lip, and are characterized by small, translucent, light-blue blisters, usually the size of a soybean. All three are benign lesions, but treatment varies considerably.