Tooth pain when drinking cold water is commonly caused by deep caries, dentin hypersensitivity, pulpitis, etc. It needs a detailed examination in person to determine the specific situation. Generally speaking, deep caries can be seen by visual examination or film, and the hard tissues of the teeth are damaged, and the pain will be obvious when encountering hot or cold stimulation. In case of dentin allergy, in addition to irritating toothache when drinking cool water, sometimes inhaling cool air will also cause toothache, so you can brush your teeth with toothpaste with desensitizing effect or go to dentistry for desensitizing treatment. In addition, if you have pulpitis, you will not only have pain when you encounter hot or cold stimulation, but also have spontaneous pain, so you need to go to dentistry to have root canal treatment to remove the pulp.