A mole-like black spot on one side of the tongue may be caused by bite wounds, moles, seborrheic keratosis and other conditions. 1. Bite: If you accidentally bite your tongue and do not take timely treatment measures, and often consume spicy and stimulating food, it will lead to localized bruising and accumulation of blood, which will lead to the appearance of a nevus-like black spot on one side of the tongue. 2. Nevus: the cause of most nevi is unknown, mostly considered to be related to heredity, developmental defects, drugs, immunosuppression, hormone level changes and other factors. Acquired nevus will usually appear less than 6mm in diameter spots or papules, can be brown, brown, black, etc., can also be manifested as a nevus-like black spot on one side of the tongue. Some patients may also be accompanied by itching, pain and other symptoms. 3. Seborrheic keratosis: the exact cause and pathogenesis of the disease is not clear, mostly considered to be related to skin aging, heredity, genetic mutation, ultraviolet radiation, viral infections and other factors. Generally, the skin lesions occur in the oral mucosa, palms of the hands, head and other parts of the face, can also appear in the tongue, mostly manifested as round or oval plaques, patches, etc., the color will be from skin color to light brown to black, which can also appear on one side of the tongue there is a nevus-like black spots phenomenon. It is recommended that patients with nevus-like black spots on one side of the tongue should seek medical attention to clarify the cause of the disease and then seek reasonable treatment.