Why Doctors Prescribe Hydrochlorothiazide

Hydrochlorothiazide is a thiazide-type diuretic. Also known as water pills, diuretics are medicines used to reduce the buildup of fluid in the body. It works by causing the kidneys to move or get rid of extra or unnecessary fluid and salt out of the body through urine. So, you’ll be peeing more often than usual when you take a diuretic. In medical terminology, this is called diuresis.

There are three types of diuretics: potassium-sparing diuretic, loop diuretic, and thiazide-type diuretic. Potassium-sparing diuretics expel fluids without lowering the potassium levels in the body. It is often prescribed to people at risk of losing potassium. Examples of potassium-sparing diuretics include spironolactone (Aldactone), eplerenone (Inspra), triamterene (Dyrenium), and amiloride.

Loop diuretics are often prescribed for heart failure treatment. Examples of loop diuretics include bumetanide, furosemide (Lasix), and torsemide (Demadex).

Finally, thiazide-type diuretics are the most commonly prescribed among the three. It reduces fluids in the body and relaxes the blood vessels. Examples of thiazide-type diuretics or hydrochlorothiazide are Zide, Oretic, Esidrix, Ezide, Microzide, and Hydrodiuril. It is sold as a solution, tablet or capsule, and it is usually taken one or twice a day, though if you’re in the hospital, it could also be given through an IV in your arm.

FDA-Approved Hydrochlorothiazide Uses

There are only two indications for hydrochlorothiazide which have been approved by the U.S. Food and Drug Administration (FDA). The medication is used to treat hypertension and peripheral edema.


Lower high blood pressure

Hydrochlorothiazide has been shown to reduce major cardiovascular events. It works by preventing sodium from being reabsorbed by the body. It also inhibits the sodium chloride cotransporter which induces natriuresis, or the process of expelling sodium through the urine by the kidneys, and diuresis.

In other words, hydrochlorothiazide flushes out excess salt and water from the body via urine. With some of the water expelled out of the body, the quantity of blood flowing through the blood vessels is reduced, which in turn lowers your blood pressure.

It has been used as an antihypertensive diuretic for more than 60 years now, after being approved for use as a treatment for high blood pressure in the 1960s. It can be used on its own or doctors might prescribe it in combination with other antihypertensive medications.


Treat peripheral edema

Another FDA-approved indication for hydrochlorothiazide is as a medication for peripheral edema, which is the swelling of your hands or legs. The swelling results from fluid retention or when body tissues hold excess fluid. This can be caused by certain medication, such as corticosteroids and estrogen, and underlying diseases related to the heart, kidney and liver.

Hydrochlorothiazide are usually used as an adjunctive therapy, which is given in addition to or after primary or initial treatment. The first-line treatment for peripheral edema is typically loop diuretics.

Off-Label Uses

Hydrochlorothiazide is also taken for other purposes, although these uses are not currently included in the list of FDA-approved indications.


Treat Diabetes Insipidus

Some people use the thiazide-type diuretic to treat diabetes insipidus. This condition is also known as water diabetes and is characterized by increased urination and thirst. However, unlike diabetes mellitus, which is caused by high blood sugar or glucose, diabetes insipidus results from an issue with the antidiuretic hormone (ADH) or vasopressin.

This hormone has a key role in regulating the body’s fluid balance. It has a two-fold function: One is increasing the body’s ability to reabsorb water and the other is decreasing water excretion. When someone has diabetes insipidus, their bodies either don’t make enough vasopressin or their kidneys don’t use it properly.

Either way, this results in peeing as many as 20 quarts (18.9 liters) in a day, according to the National Institute of Diabetes and Digestive and Kidney Diseases. Compare that to the 1 to 3 quarts (946.4 ml  to 2.84 l) that a healthy adult typically urinates daily.


Prevent Kidney Stones

Kidney stones, also known as renal calculi or nephrolithiasis, are crystal concretions that typically form in the kidney but can also be found in the urethra. They can be as small as a grain of sand or a tiny pebble, but they are most often larger.

Under normal circumstances, substances like calcium, oxalate and phosphate are dissolved in urine and leave the body through the urethra without pain. However, under certain conditions, such as if there is too much waste and too little water, these substances become too concentrated and form as crystals.

Calcium stones or calcium oxalate is the most common kidney stones. The other types of kidney stones are struvite, uric acid, and cystine.

Larger stones are painful and they might even need to be removed through surgery, while some types of kidney stones can be broken down or removed by medication. For instance, your doctor may prescribe antibiotics for struvite stones or allopurinol for uric acid stones. Or, they could also instruct you to take Tamsulosin to help your urethra relax and allow the stone to pass.

Thiazide-type diuretics like hydrochlorothiazide will be prescribed if you have calcium stones. This medication will help keep the calcium in your bones and reduce high levels of calcium in the urine. However, as thiazide diuretics can lead to potassium loss – a common side effect of the drug – your doctor will most likely also give you a potassium supplement while you’re taking hydrochlorothiazide.

Talk to Your Doctor About Hydrochlorothiazide

If you’re having problems with high blood pressure, swelling, kidney stones or diabetes insipidus, visit your doctor and discuss with them the possibility of taking hydrochlorothiazide. If prescribed, it’s important to follow your doctor’s instructions exactly.

Note that like other medications, hydrochlorothiazide may cause side effects. These include muscle cramps, nausea, or dizziness. Inform your doctor right away if you experience any troublesome side effects.

If you have preexisting conditions, such as anuria or sulfonamide allergy, don’t forget to tell your doctor about them. People with severe hepatic impairment, for instance, are at risk of developing hepatic coma so taking hydrochlorothiazide is used cautiously. However, those with underlying adrenal insufficiency should avoid taking the drug completely.