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

Increased thirst; Polydipsia; Excessive thirst

Drinking lots of water is usually healthy. But 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 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 large decrease in blood volume
• Diabetes
• Diabetes insipidus
• Medicines such as anticholinergics, demeclocycline, diuretics, phenothiazines  
• Loss of body fluids from the bloodstream into the tissues due to conditions such as severe infections (sepsis) or burns, or heart, liver, or kidney failure
• A mental disorder called psychogenic polydipsia

Because thirst is the body's signal to replace water loss, it is usually appropriate to drink plenty of liquids.

For thirst caused by diabetes, follow the prescribed treatment to properly control your blood sugar level.

• Excessive thirst is ongoing and unexplained
• Thirst is accompanied by other unexplained symptoms, such as blurry vision and fatigue
• You are passing more than 5 quarts of urine per day

The health care provider will get your medical history and perform a physical examination.

Medical history questions may include:

• How long have you been aware of having increased thirst?
• Is it consistent during the day?
• Is it worse during the day?
• Did it develop suddenly or slowly?
• Are you eating more salty or spicy foods?
• How much salt do you have each day?
• Did you change your diet?
• Have you noticed an increased appetite?
• Have you noticed an unintentional weight gain?
• Have you noticed an unintentional weight loss?
• Has your activity level recently increased?
• What other symptoms are happening at the same time?
• Have you recently suffered a burn or other injury?
• Are you urinating more or less frequently than usual?
• Are you producing more or less urine than usual?
• Have you noticed any bleeding?
• Are you sweating more than usual?
• Is there any swelling in your body?
• Do you have a fever?

Tests that may be ordered include the following:

• Blood glucose level
• CBC and blood differential
• Serum calcium
• Serum osmolality
• Serum sodium
• Urinalysis
• Urine osmolality

Based on your evaluation and any tests, your health care provider will recommend treatment if needed. For example, if tests show you have diabetes, you will need to start treatment for this condition.

A very strong, constant urge to drink may be sign of a psychological problem. A psychological evaluation may be recommended if the health care provider suspects a psychological compulsive thirst. Your fluid intake and output will be closely watched.

Gibbs MA, Tayal VS. Electrolyte disturbances. In: Marx JA, Hockberger RS, Walls RM, et al, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2009:chap 123.