Excessive thirst is an abnormal feeling of always needing to drink fluids.

Drinking lots of water is usually healthy. However, the urge to drink too much may be the result of a physical or emotional disease. Excessive thirst may be a symptom of high blood sugar (hyperglycemia). It can be an important clue in detecting diabetes.

Excessive thirst is a fairly common symptom. It is often the reaction to fluid loss during exercise, or to eating salty foods.

• A recent salty or spicy meal
• Bleeding enough to cause a significant decrease in blood volume
• Diabetes
• Diabetes insipidus
• Drugs such as anticholinergics, demeclocycline, diuretics, phenothiazines
• Excessive loss of water and salt (possibly due to not drinking enough water, profuse sweating, diarrhea, or vomiting)
• Loss of body fluids from the bloodstream into the tissues due to:
  • Conditions such as severe infections (sepsis) or burns
  • Heart, liver, or kidney failure
• Psychogenic polydipsia, the result of a mental disorder