hydrochlorothiazide (Microzide, Hydrodiuril)

• Hydrochlorothiazide is used to treat excessive fluid accumulation and swelling (edema) of the body caused by heart failure, cirrhosis, chronic kidney failure, corticosteroid medications, and nephrotic syndrome.
• It also is used alone or in conjunction with other blood pressure lowering medications to treat high blood pressure.
• Although hydrochlorothiazide is approved for treating edema in cirrhosis of the liver, it is rarely used because of the availability of other diuretics that are more effective.
• Hydrochlorothiazide can be used to treat calcium-containing kidney stones because it decreases the amount of calcium excreted by the kidneys in the urine and thus decreases the amount of calcium in urine to form stones.

Yes

Hydrodiuril, Ezide, Hydro-Par, and Microzid are brand names that are no longer available in the US.

Yes

Side effects of hydrochlorothiazide include

• weakness,
• low blood pressure,
• light sensitivity (rash caused by sunlight),
• impotence,
• nausea, and
• abdominal pain.

More serious side effects include

• electrolyte disturbances,
• pancreatitis,
• jaundice, and
• anaphylaxis (a life-threatening allergic reaction).

Patients allergic to sulfa may also be allergic to hydrochlorothiazide because of the similarity in the chemical structure of the medications.

Hydrochlorothiazide can aggravate kidney dysfunction and is used with caution in patients with kidney disease. Hydrochlorothiazide can lower blood potassium, sodium, and magnesium levels. Low potassium and magnesium levels can lead to abnormalities in heart rhythm, especially in patients already taking digoxin (Lanoxin). During hydrochlorothiazide treatment, supplementation with potassium is common to prevent low potassium levels.

Blood uric acid levels can increase during hydrochlorothiazide treatment, and this elevation may cause an episode of acute gout in some individuals. Thiazide diuretics may increase blood sugar (glucose) levels and precipitate diabetes.

• Hydrochlorothiazide may be taken with or without food.
• The usual adult dose for hypertension is 12.5 to 50 mg once daily.
• The usual adult dose for treating edema is 25-100 mg once daily or in divided doses.

• Hydrochlorothiazide reduces the elimination of lithium (Lithobid, Eskalith) by the kidneys and can lead to lithium toxicity.
• Nonsteroidal anti-inflammatory drugs (NSAIDs), for example, ibuprofen (Motrin), may reduce the blood pressure lowering effects of hydrochlorothiazide. Blood sugar levels can be elevated by hydrochlorothiazide, necessitating adjustment in the doses of medications that are used for treating diabetes.
• Combining hydrochlorothiazide with corticosteroids may increase the risk for low levels of blood potassium and other electrolytes. Low blood potassium (hypokalemia) can increase the toxicity of digoxin (Lanoxin).
• Cholestyramine (Questran, Questran Light) and colestipol (Colestid) bind to hydrochlorothiazide and reduce its absorption from the gastrointestinal tract by 43% to 85%.

• There are no adequate studies of hydrochlorothiazide in pregnant women. Thiazides may increase the risk of fetal or neonatal jaundice, low platelet levels, and possibly other adverse reactions that have occurred in adults.
• Hydrochlorothiazide is excreted in breast milk. Intense diuresis using hydrochlorothiazide may reduce the production of breast milk. Otherwise hydrochlorothiazide is considered safe to use during nursing if required by the mother.

What preparations of hydrochlorothiazide are available?

• Tablets: 12.5, 25, 50 and 100 mg
• Capsules: 12.5 mg

How should I keep hydrochlorothiazide stored?

Hydrochlorothiazide should be stored at room temperature, 15 C to 30 C (59 F to 86 F), in a tight, light-resistant container.

How does hydrochlorothiazide work?

• Hydrochlorothiazide is a diuretic (water pill) used for treating high blood pressure (hypertension) and accumulation of fluid (edema). It works by blocking salt and fluid reabsorption from the urine in the kidneys, causing increased urine output (diuresis). Its mechanism of action in lowering high blood pressure is not well understood.
• Hydrochlorothiazide is used in combination with many other drugs

When was hydrochlorothiazide approved by the FDA?

• The FDA approved hydrochlorothiazide in February 1959.