Also found in: Dictionary, Thesaurus.


(hye-droe-klor-oh-thye-a-zide) ,


(trade name),


(trade name),


(trade name)


Therapeutic: antihypertensives
Pharmacologic: thiazide diuretics
Pregnancy Category: B


Management of mild to moderate hypertension.Treatment of edema associated with:
  • HF,
  • Renal dysfunction,
  • Cirrhosis,
  • Glucocorticoid therapy,
  • Estrogen therapy.


Increases excretion of sodium and water by inhibiting sodium reabsorption in the distal tubule.
Promotes excretion of chloride, potassium, hydrogen, magnesium, phosphate, calcium and bicarbonate.
May produce arteriolar dilation.

Therapeutic effects

Lowering of BP in hypertensive patients and diuresis with mobilization of edema.


Absorption: Rapidly absorbed after oral administration.
Distribution: Distributed into extracellular space; crosses the placenta and enters breast milk.
Metabolism and Excretion: Excreted mainly unchanged by the kidneys.
Half-life: 6–15 hr.

Time/action profile (diuretic effect)

PO†2 hr3–6 hr6–12 hr
†Onset of antihypertensive effect is 3–4 days and does not become maximal for 7–14 days of dosing


Contraindicated in: Hypersensitivity (cross-sensitivity with other thiazides or sulfonamides may exist); Some products contain tartrazine and should be avoided in patients with known intolerance; Anuria; Lactation: Lactation.
Use Cautiously in: Renal or hepatic impairment; Obstetric: Jaundice or thrombocytopenia may be seen in the newborn.

Adverse Reactions/Side Effects

Central nervous system

  • dizziness
  • drowsiness
  • lethargy
  • weakness


  • hypotension


  • anorexia
  • cramping
  • hepatitis
  • nausea
  • vomiting


  • stevens johnson syndrome (life-threatening)
  • photosensitivity
  • rash

Ear, Eye, Nose, Throat

  • acute angle-closure glaucoma
  • acute myopia


  • hyperglycemia

Fluid and Electrolyte

  • hypokalemia (most frequent)
  • dehydration
  • hypercalcemia
  • hypochloremic alkalosis
  • hypomagnesemia
  • hyponatremia
  • hypophosphatemia
  • hypovolemia


  • blood dyscrasias


  • hyperuricemia
  • hypercholesterolemia


  • muscle cramps


  • pancreatitis


Drug-Drug interaction

Additive hypotension with other antihypertensives, acute ingestion of alcohol, or nitrates. .Additive hypokalemia with corticosteroids, amphotericin B, piperacillin, or ticarcillin.↓ the excretion of lithium.Cholestyramine orcolestipol ↓ absorption.Hypokalemia ↑ risk of digoxin toxicity.NSAIDs may ↓ effectiveness. .


When used as a diuretic in adults, generally given daily, but may be given every other day or 2–3 days/week
Oral (Adults) 12.5–100 mg/day in 1–2 doses (up to 200 mg/day; not to exceed 50 mg/day for hypertension; doses above 25 mg are associated with greater likelihood of electrolyte abnormalities).
Oral (Children >6 mo) 2 mg/kg in 2 divided doses (not to exceed 200 mg/day).
Oral (Children <6 mo) Up to 2–4 mg/kg/day in 2 divided doses (not to exceed 37.5 mg/day).

Availability (generic available)

Tablets: 25 mg, 50 mg, 100 mg Cost: Generic — 25 mg $10.00 / 90, 50 mg $10.00 / 90
Capsules: 12.5 mg Cost: Generic — $10.00 / 90
In combination with: numerous antihypertensives. See combination drugs.

Nursing implications

Nursing assessment

  • Monitor BP, intake, output, and daily weight and assess feet, legs, and sacral area for edema daily.
    • Assess patient, especially if taking digoxin, for anorexia, nausea, vomiting, muscle cramps, paresthesia, and confusion. Notify health care professional if these signs of electrolyte imbalance occur. Patients taking digitalis glycosides are at risk of digitalis toxicity because of the potassium-depleting effect of the diuretic.
    • If hypokalemia occurs, consideration may be given to potassium supplementation or decreasing dose of diuretic.
    • Assess patient for allergy to sulfonamides.
    Assess patient for skin rash frequently during therapy. Discontinue diuretic at first sign of rash; may be life-threatening. Stevens-Johnson syndrome may develop. Treat symptomatically; may recur once treatment is stopped.
  • Hypertension: Monitor BP before and periodically throughout therapy.
    • Monitor frequency of prescription refills to determine compliance.
  • Lab Test Considerations: Monitor electrolytes (especially potassium), blood glucose, BUN, serum creatinine, and uric acid levels before and periodically during therapy.
    • May cause ↑ serum and urine glucose in diabetic patients.
    • May cause ↑ serum bilirubin, calcium, creatinine, and uric acid, and ↓ serum magnesium, potassium, sodium, and urinary calcium concentrations.
    • May cause ↑ serum cholesterol, low-density lipoprotein, and triglyceride concentrations.

Potential Nursing Diagnoses

Excess fluid volume (Indications)
Risk for deficient fluid volume (Side Effects)
Deficient knowledge, related to medication regimen (Patient/Family Teaching)


  • Administer in the morning to prevent disruption of sleep cycle.
    • Intermittent dose schedule may be used for continued control of edema.
  • Oral: May give with food or milk to minimize GI irritation. Tablets may be crushed and mixed with fluid to facilitate swallowing.

Patient/Family Teaching

  • Instruct patient to take this medication at the same time each day. Take missed doses as soon as remembered but not just before next dose is due. Do not double doses.
    • Instruct patient to monitor weight biweekly and notify health care professional of significant changes.
    • Caution patient to change positions slowly to minimize orthostatic hypotension. This may be potentiated by alcohol.
    • Advise patient to use sunscreen and protective clothing to prevent photosensitivity reactions.
    • Instruct patient to discuss dietary potassium requirements with health care professional (see ).
    • Instruct patient to notify health care professional of medication regimen before treatment or surgery.
    • Advise patient to report rash, muscle weakness, cramps, nausea, vomiting, diarrhea, or dizziness to health care professional.
    • Emphasize the importance of routine follow-up exams.
  • Hypertension: Advise patients to continue taking the medication even if feeling better. Medication controls but does not cure hypertension.
    • Encourage patient to comply with additional interventions for hypertension (weight reduction, low-sodium diet, regular exercise, smoking cessation, moderation of alcohol consumption, and stress management).
    • Instruct patient and family in correct technique for monitoring weekly BP.
    • Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult health care professional before taking other Rx, OTC, or herbal products,, especially cough or cold preparations.

Evaluation/Desired Outcomes

  • Decrease in BP.
    • Decrease in edema.
Drug Guide, © 2015 Farlex and Partners