Medical Author: Omudhome Ogbru, Pharm.D.
Medical Editor: Jay Marks, M.D.
GENERIC NAME: hydrochlorothiazide
BRAND NAMES: Hydrodiuril, Ezide, Hydro-Par, Microzide, and many combinations
with other drugs
DRUG CLASS AND MECHANISM: Hydrochlorothiazide is a diuretic (water
pill) used for treating high blood pressure (hypertension) and accumulation of
fluid. It works by blocking salt and fluid reabsorption in the kidneys, causing
increased urine output (diuresis). The mechanism of its action in lowering high
blood pressure is not well understood.
PRESCRIPTION: Yes
GENERIC AVAILABLE: Yes
PREPARATIONS: Tablets: 12.5, 25, 50, and 100 mg; Capsules: 12.5 mg
STORAGE: Hydrochlorothiazide should be stored at room temperature, 15
to 30 C (59 to 86 F), in a tight, light-resistant container.
PRESCRIBED FOR: 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 more potent 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.
DOSING: 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.
DRUG INTERACTIONS: Hydrochlorothiazide reduces the elimination of
lithium (Lithobid) by the kidneys and can lead to lithium toxicity.
Nonsteroidal antiinflammatory
drugs, for example, ibuprofen, may reduce the blood pressure 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 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%-85%.
PREGNANCY: There are no adequate studies of hydrochlorothiazide in
pregnant women.
NURSING MOTHERS: Hydrochlorothiazide is excreted in breast milk. There
is some evidence that it may reduce production of
breast milk.
SIDE EFFECTS: Side effects of hydrochlorothiazide include weakness,
low blood pressure, light sensitivity (rash caused by sunlight), impotence,
nausea, abdominal pain,
electrolyte disturbances, pancreatitis, jaundice,
anaphylaxis, and rashes, both mild and severe. 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 latent diabetes.
Last Editorial Review: 12/15/2008
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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