Polydipsia or excessive thirst can be caused by underlying medical conditions such as diabetes mellitus or simply not drinking enough water. Coupled with excessive thirst, it usually presents with symptoms such as fatigue, blurry vision, headaches, frequent urination, and/or dry mouth. 

Eager to ‘quench’ your ‘thirst’ and learn more about the signs and symptoms, causes, current diagnostic and treatment methods as well as complications of polydipsia, and when to see a doctor? Keep reading! 

Introduction

Definition of polydipsia

Polydipsia¹ is a medical term for excessive thirst, which usually results in excessive consumption of fluids and in turn, frequent or excessive urination (polyuria). 

Importance of understanding its causes and symptoms

It is essential to understand the causes and symptoms of polydipsia because if left untreated, polyuria¹ can lead to hyponatremia (low sodium levels in the blood) and eventually, seizures or even death, in severe cases. 

Causes 

Physiological causes

Polydipsia can be a ‘normal’ physiological response to not drinking enough fluids² throughout the day. Insufficient fluid intake is a major factor contributing to dehydration, which in turn causes the body to ‘communicate’ a strong need to drink and replenish lost fluids by increasing thirst. 

People who exercise,² particularly in hot climates, are at significant risk of dehydration as they are likely to lose a lot of water in sweat and therefore, should take extra care to replenish lost fluids during and after exercise. 

Medical conditions

In contrast to dehydration, some people can drink plenty of fluids and still feel extremely thirsty constantly, every day, for weeks to even months. No matter how much fluid they drink, it never seems able to quench their thirst. 

This is because, polydipsia can sometimes be caused by certain medical conditions including:^1,2

• Diabetes mellitus: hyperglycaemia or high glucose (sugar) levels in the blood is one of the main ‘warning’ signs of diabetes mellitus² that can result in polydipsia 
• Diabetes insipidus: occurring due to the kidneys and pituitary gland not being able to retain water as they normally would, diabetes insipidus² results in polyuria, which increases the urge to drink to ‘make up’ for lost fluids (dehydration) 
• Hypercalcemia: any electrolyte imbalances including hypercalcemia,¹ which is characterised by elevated calcium levels in the blood, can result in polydipsia by decreasing the efficiency of the kidneys and making them work harder than usual to balance fluid input (intake) and output (urine) in the body 
• Psychogenic polydipsia: polydipsia can be experienced in patients with mental disorders such as anxiety, but mainly in patients with psychiatric disorders¹ including schizophrenia, schizoaffective disorder, bipolar disorder, and psychotic depression, hence the name

Over 18%¹ of patients with psychiatric disorders develop polydipsia due to:

• “Compulsive water drinking’’ (water intoxication): possibly as a way of ‘coping’ with the psychotic episodes and/or dysfunction in the hypothalamus, which is a region in the brain that regulates the pituitary gland 
• Antipsychotic medications: which can result in dry mouth (xerostomia) and in turn polydipsia

Medications

In addition to antipsychotics, other medications¹ can cause polydipsia including: 

• Diuretics
• Certain antidepressants

It is thought that antipsychotic medications, diuretics, and certain antidepressants may cause polydipsia by decreasing the amount of arginine vasopressin or antidiuretic hormone (ADH)¹ secreted by the pituitary gland from the hypothalamus. The main function of ADH is to maintain the amount of fluids inside the body by making the kidney retain or ‘hold onto’ water. 

Therefore, high levels of ADH cause the kidney to retain water whilst low ADH levels cause the kidney to excrete large amounts of water in urine (polyuria). The body compensates for significant loss of water by increasing thirst (polydipsia), as is thought to be the case in some patients taking any of the aforementioned medications. 

Compulsive water drinking (in healthy people)

Although people with the above-mentioned medical conditions are at higher risk of developing polydipsia, health-conscious people with no history of psychiatric disorders who consciously engage in compulsive water drinking are also susceptible to polydipsia, specifically “dipsogenic polydipsia (compulsory water drinking)’’.¹ 

Drinking plenty of water is essential to improve and maintain overall health, however, excessive water intake can be too much of a good thing. 

Unfortunately, compulsive water drinking in healthy people is on the rise due to the increasing number of diets and lifestyle programmes encouraging excessive water intake as a way to ‘’lose’’ weight, ‘flush’ ‘’toxins’’ outside the body, and ‘‘mask’’ hunger, which is problematic in itself. 

Excessive alcohol and/or caffeine intake 

Alcohol and coffee are both diuretics and therefore increase urination (polyuria) and in turn thirst (polydipsia).^1,2

Signs and symptoms 

The signs and symptoms of polydipsia include:^1,2

• Excessive thirst(main sign and symptom): Usually occurs despite drinking excessive amounts of fluids for days
• Excessive fluid intake: mainly water, but coffee and alcohol are major culprits as well 
• Frequent or excessive urination (polyuria)
• Dry mouth
• Blurred vision
• Extreme tiredness (fatigue)
• Excessive hunger (polyphagia) in some cases: It could be a sign of diabetes mellitus
• Headaches

Some people with polydipsia, such as healthy people with compulsive water drinking, may present with symptomatic hyponatremia.¹ 

The main signs and symptoms of hyponatremia¹ include:

• Nausea
• Vomiting
• Confusion
• Loss of muscle control (ataxia)
• Coma
• Seizures
• Death 

Diagnosis 

A healthcare provider will diagnose a suspected patient with polydipsia by performing a series of tests in the following order:^1,2

Physical examination and medical history: to assess multiple factors that may influence thirst including: 

• Medical conditions 
• Medications 
• Diet: specifically one associated with excessive fluid (e.g. water, alcohol, and/or caffeine) and/or spicy or salty food intake 
• Smoking 
• Sweat
• Physical activity
• Weight: specifically unexplained weight loss as it is a sign of diabetes 
• Urination

Blood tests including

• Full blood count (FBC): to check the level of red blood cells, haemoglobin, platelets, and white blood cells 
• Sodium blood test: to check for the presence of hyponatremia as it is a major complication of polydipsia 
• Calcium blood test: to rule out hypercalcemia 
• Blood glucose test: to check the level of glucose (sugar) in the blood and rule out diabetes, which usually presents with hyperglycemia 

Urine tests measuring

• 24-hour urine volume: a urine volume greater than 40-50 ml/kg in a twenty-four-hour period indicates polyuria 
• Urine electrolytes
• Urine osmolality: to measure urine concentration and therefore evaluate kidney functioning 

Electrolyte panel: to measure serum electrolytes including: 

• Sodium: to rule out hyponatremia 
• Calcium: to rule out hypercalcemia
• Potassium: to rule out hypokalemia, which can also cause polydipsia 

Imaging studies: to rule out conditions that affect the thirst centre (hypothalamus) in the brain, including schizophrenia. These may involve either:

• Magnetic resonance imaging (MRI): to take two-dimensional (2D) detailed images of the brain using a magnetic field, radio waves, and a computer

Along with dysregulation of the hypothalamus, scientists believe that the hippocampus¹ is also responsible for psychogenic polydipsia 

Therefore, an MRI test showing a smaller hippocampus coupled with compulsive water drinking is a major indicator of psychogenic polydipsia, mainly in patients with schizophrenia 

• Computed tomography (CT): to take three-dimensional (3D) images of the brain using X-rays and a computer 

Treatment

To date, there is no clear or proven treatment¹ approach for polydipsia. The treatment provided usually depends on the type, cause, and severity of polydipsia, and therefore involves:

• Addressing underlying medical conditions (the ‘’root cause’’): for example, if the patient’s polydipsia is caused by diabetes insipidus, a healthcare provider will advise drinking more fluids to prevent dehydration 
• Fluid intake management: by, for example, referring patients to a counselor for counseling sessions to make them aware of their fluid intake and provide them with strategies to better manage it
• Medication adjustments or changes: if the polydipsia is caused by certain medications 

Lifestyle changes which usually involve:

• Adjusting fluid intake by either drinking more water if dehydrated or drinking less water if the patient has psychogenic or dipsogenic/habitual polydipsia
• Avoiding drinking alcohol and/or caffeine 
• Avoiding smoking 
• Avoiding spicy or salty foods
• Managing blood sugars more effectively 
• Eating a more nutritious and balanced diet: to correct any electrolyte imbalances caused by the polydipsia 

Complications

The complications¹ of polydipsia are severe and mainly occur due to hyponatremia. Examples include:

• Nausea
• Vomiting
• Blurred vision
• Tremors
• Dizziness
• Ataxia
• Confusion
• Fatigue
• Seizures: The most common complication of hyponatremia 
• Permanent and severe brain damage: especially if sodium levels are corrected too rapidly in a patient with hyponatremia (‘’central pontine myelinolysis’’)

Therefore, sodium levels should not be corrected more than 8-10 mmol/L in 24 hours 

• Death: if left untreated, polydipsia and in turn hyponatremia, may result in death 

When to see a doctor 

See a doctor² immediately if you experience any of the signs of polydipsia discussed in this article, including

• Unquenchable excessive thirst that lasts for several days
• Frequent and/or excessive urination
• Blurred vision
• Fatigue
• Polyphagia 

This is especially important if pregnant or diabetic. 

Summary 

Polydipsia is a medical term for excessive and unquenchable thirst that can lastfor several days to even months. It usually results in excessive fluid intake, excessive urination (polyuria), and eventually, hyponatremia. People with polydipsia may present with:

• Fatigue
• Blurred vision
• Dry mouth
• Headaches
• Nausea
• Vomiting
• Excessive hunger (polyphagia)

Polydipsia has many causes including:

• Insufficient (dehydration) or excessive (‘’compulsive water drinking’’) fluid intake 
• Excessive alcohol and/or caffeine intake 
• Profusely sweating during exercise 
• Excessive consumption of salty and/or spicy foods 
• Certain medications e.g. antidepressants or antipsychotics
• Medical conditions e.g. diabetes mellitus or schizophrenia 

At present, diagnosis for polydipsia mainly involves:

• Blood tests e.g. FBC 
• Urine tests
• Electrolyte panel
• Imaging studies e.g. MRI 

Treatment for polydipsia is provided based on the cause or underlying medical condition. 

It is critical to stress the importance of understanding and addressing the causes and symptoms of polydipsia as it can result in permanent brain damage, seizures, and even death if left untreated. 

Just as not drinking enough water is harmful, drinking too much water does more harm than good. After all, it is all about balance in the end.