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What causes excessive thirst? 25 possible conditions

Excessive Thirst

Your body needs water to function properly. For example, water helps to regulate your body temperature, lubricate your joints, and remove waste from your body. Adequate daily water intake is very important. Furthermore, it is important to increase your usual water intake when you are ill, exposed to hot temperatures, or engaged in physical activities.

However, if your thirst is stronger than usual and continues even after you drink, seek medical help immediately—especially if your thirst is accompanied by blurred vision and fatigue.

Causes of Excessive Thirst

It is normal to feel thirsty after eating salty or spicy foods, or after engaging in strenuous exercise or sporting events, especially when it is hot. You may also feel thirsty when you suffer from diarrhea, vomiting, burns, or a significant loss of blood. Some prescription medications also cause thirst.

Frequent excessive thirst and/or thirst that won’t be quenched can be symptoms of serious medical conditions, such as:

  • dehydration: Dehydration occurs when you lack the proper amount of fluids for your body to function properly. Severe dehydration is life threatening, especially for infants and young children. Dehydration can be caused by illness, profuse sweating, too much urine output, vomiting, or diarrhea.
  • diabetes: Excessive thirst can be caused by high blood sugar (hyperglycemia), and is often one of the first noticeable symptoms of diabetes.
  • diabetes insipidus: With this form of diabetes, your kidneys are unable to conserve water, leading to excessive thirst.
  • dipsogenic diabetes insipidus: This condition is due to a defect in the thirst mechanism, causing excessive thirst and excessive urine output.
  • heart, liver, or kidney failure
  • psychogenic polydipsia: This is a psychiatric disorder that causes people to drink too much.
  • sepsis: This is a dangerous illness caused by a severe reaction to bacteria or other germs.

When to Seek Medical Attention

Thirst is your body’s way of telling you that it is low on fluids. In normal circumstances, you should be able to quench your thirst fairly quickly. However, if your urge to drink remains constant, or does not go away after you drink, it may be a sign of a serious health problem, especially if combined with other symptoms. This constant urge to drink could also be a psychological problem.

Consult with your doctor if:

  • thirst is persistent, regardless of how much you drink
  • you also have blurry vision, excessive hunger, or cuts or sores that do not heal
  • you are also fatigued
  • you are urinating more than five quarts a day

Diagnosing Excessive Thirst

To help diagnose the reason for your excessive, unresolved thirst, your doctor will ask you for a complete medical history, including any previously diagnosed conditions. Be prepared to list all of your prescription and over-the-counter medications and supplements. Some questions your doctor may ask include:

  • How long have you been aware of your symptoms?
  • Are you also urinating more than usual?
  • Did your symptoms begin slowly or suddenly?
  • Does your thirst increase or decrease during certain times of the day?
  • Have you made dietary or other lifestyle changes?
  • Has your appetite for food been affected?
  • Have you gained or lost weight?
  • Have you recently had an injury or burn?
  • Are you experiencing any bleeding or swelling?
  • Have you had a fever?
  • Have you been perspiring heavily?

In addition to a physical exam, your doctor may order blood and urine tests to help provide a diagnosis. These tests may include:

  • blood glucose test
  • blood count and blood differential tests
  • urinalysis and urine osmolality tests
  • serum calcium, osmolality, and sodium tests

Depending on the test results, your doctor may refer you to a specialist.

Treating Excessive Thirst

Treatment and prognosis will depend on the diagnosis.

How Much Fluid Do You Normally Need?

To remain healthy, you need to drink fluid regularly throughout the day. You can increase your water intake by also eating water-rich foods, such as celery, watermelon, tomatoes, oranges, and melons.  A good rule of thumb to know if you are getting enough fluids is to check your urine.  If it is light in color, high in volume, and does not have a heavy smell, you are probably getting enough fluid. 

Every organ, tissue, and cell in your body needs water. Water helps your body to:

  • maintain a normal temperature
  • lubricate and cushion your joints
  • protect the spinal cord
  • rid your body of waste through perspiration, urination, and bowel movements

You need to take in extra fluids when you:

  • are outdoors in hot weather
  • are engaging in a rigorous activity
  • have diarrhea
  • are vomiting
  • have a fever

If you fail to replenish the fluids you lose and fail to respond to your thirst by drinking fluids, you can become dehydrated.

Risks of Excessive Thirst: Overhydration

When you try to quench excessive thirst, it is possible to drink too much. Taking in more water than you expel is called overhydration, a condition that can occur when you have kidney, liver, or heart disorders or drink too much liquid to compensate for fluid loss. Overhydration can cause confusion and seizures.

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See a list of possible causes in order from the most common to the least.


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This feature is for informational purposes only and should not be used to diagnose.
Please consult a healthcare professional if you have health concerns.