Diuretics - Uses, Types & Side Effects

Diuretics (also called water pills or fluid pills) are medicines that increase the amount of urine you produce. Urination is the body’s way of removing excess salt and water.  Not only does this relieve symptoms such as ankle swelling, it also helps to lower blood pressure.

There are several different classes of diuretics, including carbonic anhydrase inhibitors, loop diuretics, potassium-sparing diuretics, and thiazide diuretics. Each type works in a distinct way and in different parts of the kidney cell (called a nephron).


  • Carbonic anhydrase inhibitors
  • Loop diuretics
  • Miscellaneous diuretics
  • Potassium-sparing diuretics
  • Thiazide diuretics


Diuretics are used to treat conditions that have fluid retention (also called edema) as a symptom, such as heart failure, kidney failure and cirrhosis of the liver.

They are also effective at reducing blood pressure and some (such as thiazides and loop diuretics) are used in the treatment of high blood pressure (hypertension). Carbonic anhydrase inhibitors are mainly used in the treatment of glaucoma and are sometimes used off-label for altitude sickness.


When taken at the recommended dosage, diuretics are considered safe. However, they have been associated with several serious adverse effects including:

  • Stevens-Johnson syndrome, erythema multiforme and other severe reactions in people with a sulphonamide allergy who have taken a sulphonamide-containing diuretic (includes acetazolamide, thiazides, or loop diuretics)
  • Severe neurological changes have occurred in people with liver disease given loop diuretics who are already electrolyte depleted
  • Tinnitus or hearing impairment have been reported with loop diuretics, mainly after intravenous administration, or in people with kidney disease, low protein levels, or administered another medicine that may also affect hearing
  • Excessive urination can occur which may cause dehydration with the potential for adverse cardiovascular events such as a stroke or blood clots.

Side effects:

Side effects vary, depending on the type of diuretic taken. However, more common side effects of diuretics include:

  • Changes in electrolyte levels (such as potassium, sodium, calcium or magnesium levels), depending on the type of diuretic
  • Constipation
  • Dizziness
  • Dry mouth
  • Gout
  • A headache
  • An increase in blood sugar levels
  • Muscle cramps
  • Stomach upset
  • Tiredness

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* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.