Quick facts
| Fact | Hydrochlorothiazide |
|---|---|
| Drug class[1][2] | Thiazide diuretic |
| Used for[1] | High blood pressure, alone or with other drugs; add-on treatment for edema from heart failure, cirrhosis, or corticosteroid and estrogen therapy; also used for edema from kidney disease |
| Contraindicated with[1] | Anuria (no urine output); allergy to sulfonamide-derived drugs |
| Timing by mouth[1][2] | Urine output rises within 2 hours, peaks at about 4 hours, and stays up for about 6 to 12 hours |
| Check[1][2] | Blood pressure, electrolytes (especially potassium), kidney function, intake and output, and weight |
| Metabolic effects[1] | Higher glucose and uric acid; slightly higher calcium; possibly higher cholesterol and triglycerides |
Before giving hydrochlorothiazide: potassium, sodium, and fluid status
- As the kidneys get rid of sodium, some potassium may be lost in the urine too. Watch for fluid and electrolyte imbalance: low sodium, low potassium, and low chloride with a raised blood pH (hypochloremic alkalosis). Low potassium is more likely with fast, heavy urine output, severe cirrhosis, long-term use, or poor intake by mouth.[1]
- Low potassium can cause arrhythmias and makes the heart more sensitive to digoxin toxicity.[1]
- Encourage foods high in potassium. A potassium-sparing diuretic or a potassium supplement can also prevent or treat low potassium.[1][2]
- Warning signs of fluid and electrolyte imbalance include dry mouth, thirst, weakness, confusion, muscle cramps, low urine output, low blood pressure, and a fast heart rate.[1]
- Use caution in severe kidney disease, where thiazides can cause a buildup of waste in the blood (azotemia), and in liver disease, where small fluid and electrolyte shifts can bring on hepatic coma (coma caused by liver disease).[1]
Report eye pain at once, and watch glucose, uric acid, and lithium
- A sudden drop in vision or eye pain within hours to weeks of starting can be acute angle-closure glaucoma, which can cause permanent vision loss if untreated. The first treatment is stopping hydrochlorothiazide as quickly as possible, so report it right away.[1]
- It can raise blood glucose, so insulin or oral diabetes medicines may need adjusting, and it can raise uric acid or bring on gout.[1]
- Lithium generally isn't given with diuretics, because they slow how fast the kidneys clear lithium and put the patient at high risk of lithium toxicity.[1]
Teach sun protection and slow position changes
- Protect the skin from the sun and keep up regular skin cancer screening, because hydrochlorothiazide is linked to a higher risk of non-melanoma skin cancer.[1]
- Change positions slowly, take it at the same time each day, and report big weight changes.[2]
The app's clinical tools include a drug reference for hydrochlorothiazide, built from its FDA label.
Browse clinical toolsHow it shows up on nursing exams
- Thiazides and loop diuretics lower potassium, and spironolactone raises it. In a patient taking digoxin, low potassium raises the risk of digoxin toxicity.[1][2][3]
- A sulfonamide allergy is a contraindication, and a history of sulfonamide or penicillin allergy may raise the risk of angle-closure glaucoma.[1]
Practice question
A patient takes hydrochlorothiazide and digoxin. The laboratory reference ranges are potassium 3.5 to 5.1 mEq/L, glucose 62 to 125 mg/dL, and calcium 8.8 to 10.2 mg/dL. Which result should the nurse report to the health care provider first?
- A. Blood glucose 132 mg/dL
- B. Serum potassium 3.1 mEq/L
- C. Serum calcium 10.0 mg/dL
- D. Blood pressure 126/80 mm Hg
Show the answer and why
Correct answer: B. Serum potassium 3.1 mEq/L
- A. Incorrect. 132 mg/dL is above the range, and hydrochlorothiazide can raise glucose, but a mild rise is less urgent than low potassium in a patient who takes digoxin.
- B. Correct. 3.1 mEq/L is below the range. Hydrochlorothiazide can cause hypokalemia, and low potassium makes the heart more sensitive to digoxin toxicity. Report this first.
- C. Incorrect. Thiazides can raise calcium slightly, but 10.0 mg/dL is inside the range.
- D. Incorrect. Lower blood pressure is the intended effect, and this reading is not low.
Sources for this question: [1][4][5][6]
Memory hook: HCTZ lowers potassium and sodium, can raise glucose and uric acid, and calls for sun protection.