Hydrochlorithiazide, abbreviated to HCTZ, is a thiazide diuretic used to decrease swelling and fluid retention that is often caused by heart failure, chronic kidney disease, cirrhosis, corticosteroid medications and other conditions.   It was approved in the United States in 1959 and also is known by it's brand name Microzide.  

What is it for:
HCTZ is used to high blood pressure and fluid retention (edema).  treat swelling and fluid build up which can cause high blood pressure and other complications.  

How does it work:
HCTZ is a thiazide diuretic which works at the distal renal tubule (in the kidney) to affect electrolyte reabsorption.  This results in increased excretion of sodium and chloride.  

What are some of the side effects:


  • blurred vision, dizziness, or vertigo

  • electrolyte imbalances (hyperuricemia, hyponatremia, hypercalcemia), constipation, diarrhea, nausea, vomiting, paresthesias, muscle spasm, photosensitivity, rash, restlessness, or impotence)

  • headache

  • insomnia

What I should know:


  • Do no take if you are pregnant

  • If you are diabetic, watch for signs and symptoms of hyperglycemia and report any difficulties with glycemic control to your provider

  • There are many drug-drug interactions so talk to your provider or pharmacist about the different medications you are taking (including herbal and other over the counter medications)

  • Talk to your doctor right away if you experience a significant reaction (wheezing, chest tightness, fever, itching, bad cough, blue skin color, seizures, swelling of the face, lips, tongue, or throat)

  • Talk to your doctor immediately if you experience signs of hepatic impairment, lactic acidosis, severe dizziness, angina, opthalmalgia, muscle aches, edema

  • Providers will often ask you to monitor your "in's and out's" or "I's and O's". This is to monitor and make sure that you aren't retaining excess fluid (what you are taking in should come out).

EducationJoanna Simmon