What Is Polydipsia?

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A woman drinks a glass of water

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Polydipsia is the medical term used to describe the feeling of excessive thirst even though you are drinking a lot of water in an effort to quench the thirst. If you have polydipsia, you also may find that you urinate more than normal (polyuria) and that the color of your urine may be clear.

While thirst is your body’s natural way of correcting a fluid imbalance—such as from sweating in high heat or being dehydrated from a sickness—excessive thirst can be a sign of several health conditions. Polydipsia is one of the most common symptoms associated with diabetes and is also somewhat prevalent in people with certain mental health issues, particularly schizophrenia.

There are risks associated with polydipsia, so recognizing it and treating the underlying cause is key.

What Causes Polydipsia?

Based on factors like your diet, physical activity, and climate, you might need more water from time to time. But when you are always excessively thirsty and often feel the need to drink large amounts of fluids because of it, your thirst may be abnormal.

There are several causes of polydipsia, some of which are mental and some of which are secondary to a physical condition. 

Primary Polydipsia

Primary polydipsia occurs when there is no physical condition causing your excessive thirst. There are two main types of primary polydipsia: psychogenic polydipsia and dipsogenic polydipsia.

Psychogenic Polydipsia

Psychogenic polydipsia is a behavioral issue that occurs alongside some mental health conditions like bipolar disorder, depression, and schizophrenia. It’s believed that up to 20% of people with psychiatric issues might experience psychogenic polydipsia.

People with psychogenic polydipsia have a strong urge to drink water even though there is no physiological reason to do so. Researchers are unclear exactly why it happens, but some medications may worsen the problem.

Dipsogenic Polydipsia

Dipsogenic polydipsia, also called compulsory water drinking, can be related to a dysfunction in the brain that occurs when the hypothalamus—a part in your brain that controls thirst—is altered. 

Sometimes people will experience dipsogenic polydipsia when they believe drinking excessive amounts of water is good for their health. They then compulsively consume more water than is necessary.

Secondary Polydipsia

Secondary polydipsia involves drinking excess water due to a disease or medication. The most common causes of secondary polydipsia are diabetes mellitus and diabetes insipidus. You also may experience secondary polydipsia if you are dehydrated, pregnant, or taking certain medications.

Diabetes Mellitus

Diabetes mellitus is a group of disorders, such as type 2 diabetes, characterized by hyperglycemia, or high levels of glucose. When you have hyperglycemia, you may experience polydipsia along with increased urination. Other potential symptoms of hyperglycemia include polyphagia (increased hunger), weight loss, and blurred vision.

Polydipsia occurs in diabetes mellitus as a consequence of the excess glucose that is building up in your blood. When the build-up happens, your kidneys go into overdrive to filter out the excess glucose, drawing fluids away from your body in the process. Because your body is losing fluids through frequent urination, this alerts your brain to drink more water in order to replace what is lost.

Diabetes Insipidus

Unlike diabetes mellitus, diabetes insipidus is not related to your blood glucose levels. Instead, diabetes insipidus is related to incorrect kidney function. The condition is rare and can develop when there are problems with vasopressin, a hormone that helps your kidneys balance the amount of fluid in your body. If you have diabetes insipidus, you urinate too much. That increase in urination ultimately results in polydipsia.

People who are pregnant can temporarily develop diabetes insipidus. It is rare, but when it does occur, the condition usually develops in the third trimester.

Medication-Induced Polydipsia

There are some medications that can lead to polydipsia. These include:

  • Anticholinergics, which may be used to treat urinary dysfunction, irritable bowel syndrome, Parkinson’s disease, or psychiatric conditions 
  • Diuretics, which help your body get rid of extra water and salt
  • Phenothiazines, which are used to treat psychiatric disorders

Polydipsia Symptoms

When trying to determine if you have normal thirst or excessive thirst attributed to polydipsia, it can be helpful to know how to differentiate between the two. Excessive thirst occurs when you have an abnormal urge to drink water or other liquids that persists even after you drink plenty of fluids. Meanwhile, normal thirst—which may be the result of dehydration, exercise, or illness—usually subsides after you have replenished the missing fluids.

Excessive thirst also can be differentiated from normal thirst by observing your urine output and color. For instance, with polydipsia, you may urinate as much as 12 liters of water a day while the average human output is usually around 1.5 liters of urine per day. This excessive output is usually a telltale sign of polydipsia. 

You also may notice a difference in the color of your urine. People who are dehydrated typically have urine that is darker in color. They also may not urinate as much as normal. Meanwhile, if you have polydipsia, your urine is likely diluted because of the excessive fluid intake and can be clear in color. 

Other signs and symptoms that can happen alongside polydipsia since they can be associated with the underlying cause can include: 

  • Fatigue
  • Dry mouth
  • Tiredness
  • Nausea or vomiting
  • Blurred vision
  • Tremors
  • Dizziness
  • Confusion
  • Lethargy
  • Seizures

How is Polydipsia Treated?

The treatment for polydipsia is largely influenced by the underlying condition causing it. If you do not know what is causing your excessive thirst, your healthcare provider will likely run some diagnostic tests including a urinalysis and blood tests.

If they discover that diabetes mellitus is causing your polydipsia, you will likely be asked to make lifestyle changes having to do with exercise and diet. Your healthcare provider may also prescribe medications that help you control your blood sugar. The type of medication will vary depending on whether you have type 1 diabetes or type 2 diabetes. For instance, type 1 diabetes is often treated with insulin while type 2 diabetes is often treated with metformin.

For diabetes insipidus, you may be prescribed the man-made hormone desmopressin. This medication—which comes in a nasal spray, pill, or shot—replaces the vasopressin your body is not making.

If a mental health issue is causing your polydipsia, your healthcare provider may recommend that you see a counselor or therapist so you can get any necessary treatment, such as taking medication to manage your disorder or learning to manage your compulsion to drink excessive amounts of water.

Polydipsia Complications

Because fluid balance in your body is a highly regulated process that can impact your kidneys, blood pressure, heart rate, and more, polydipsia can cause some complications and risks to your health.

One complication of polydipsia is hyponatremia, or water intoxication. Hyponatremia develops when your water intake exceeds your kidneys’ ability to eliminate the liquid. Even though this condition is rare, it can be life-threatening and cause nausea, vomiting, headache, confusion, delirium, seizures, coma, and even death.

If you have psychogenic polydipsia, you also may be at risk for incontinence and enuresis, which is involuntary urination that can happen during the day or as bedwetting at night. In more severe cases, there also is a risk of renal and congestive heart failure as well as osteoporosis and pathologic fractures.

When to See a Healthcare Provider

Being really thirsty after intense exercise, eating salty foods, or sweating a lot is likely normal and can be alleviated by drinking water. But if your thirst persists for no known reason, you may want to see a healthcare provider.

This is particularly important if your thirst is excessive and cannot be quenched no matter how much you drink. You also should take note if you are urinating frequently. These signs could be the result of an underlying condition that needs to be diagnosed and treated.

You should also see a healthcare provider if you are experiencing other symptoms like fatigue or blurry vision on top of your excessive thirst.

A Quick Review

Polydipsia is an excessive thirst. Because of your thirst, polydipsia is also accompanied by a high intake of water. A physical health condition like diabetes or a mental health condition like schizophrenia may cause polydipsia. The excessive amount of fluids you drink to quench your thirst can lead to dangerous risks and side effects, so identifying and treating the underlying condition is key.

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