Constant thirst may be caused by too much salt intake but too little water intake, or it may be caused by diseases such as open-mouth breathing, diabetes mellitus, uremia, etc. It is recommended to consult a doctor for a clear diagnosis of the specific cause. 1. People who have a heavy diet and consume too much salt during the day but do not drink enough water will often feel thirsty. You can try to reduce salt intake to 6g or less per day and ensure 1000ml of water intake to see if the thirst problem improves. 2. Disease causes of thirst include open-mouth breathing, diabetes mellitus and uremia. Some diseases such as rhinitis and obstructive apnea syndrome cause open-mouth breathing, which can lead to thirst. Typical symptoms of diabetes mellitus are “three more and one less” – drinking more, eating more, urinating more and losing weight. If thirst is accompanied by the symptoms of “three more and one less”, you need to be alert to the possibility of diabetes, and should consult a doctor promptly. Uremia is due to hypothalamic-pituitary pathology or renal resistance to vasopressin, the former is called central uremia, the latter is nephrogenic uremia, the symptoms of polyuria and thirst, can be diagnosed by the water test. After physiologic causes have been ruled out, prompt medical attention should be sought.