Lasix (furosemide) vs. thiazide diuretics

Lasix (furosemide) vs. thiazide diuretics: What's the difference?

What are Lasix and thiazide diuretics?

Lasix is a potent diuretic (water pill) used to eliminate water and salt from the body. In the kidneys, salt (made up of sodium and chloride), water, and other small molecules are filtered from the blood into the tubules of the kidney. The filtered fluid eventually becomes urine. Most of the salt and water filtered out is reabsorbed into the blood before the filtered fluid becomes urine to be eliminated from the body. Lasix blocks the absorption of salt and water from the filtered fluid in the kidney tubules, causing a significant increase in the output of urine (diuresis).

Thiazide diuretics (water pills) are used to reduce fluid accumulation in the body. They work by reducing the ability of the kidneys to reabsorb salt and water from the urine and into the body, thereby increasing the production and output of urine (diuresis). Thiazide diuretics are used to treat high blood pressure and congestive heart failure as well as the accumulation of fluid and swelling (edema) of the body caused by conditions such as heart failure, cirrhosis, chronic kidney failure, corticosteroid medications, and nephrotic syndrome.


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What are the side effects of Lasix and thiazide diuretics?


Common side effects of Lasix are:

Other important side effects include:

Increased blood sugar and uric acid levels also may occur.

Thiazide diuretics

Side effects of thiazide diuretics are dose related and include:

Other side effects and adverse reactions are:

  • An increased sensitivity to sunlight (prolonged sun exposure should be avoided).
  • Owing to their ability to increase the production of urine, these drugs may lower levels in the body of potassium and magnesium, which also are present in urine.
  • Thiazide diuretics may increase uric acid levels in blood.
  • Like other antihypertensive medications, thiazides cause sexual dysfunction.

What is the dosage of Lasix vs. thiazide diuretics?


  • The usual starting oral dose for treatment of edema in adults is 20 to 80 mg as a single dose. The same dose or an increased dose may be administered 6 to 8 hours later. Doses may be increased by 20 to 40 mg every 6 to 8 hours until the desired effect occurs. The effective dose may be administered once or twice daily. Some patients may require 600 mg daily.
  • The starting oral dose for children is 2 mg/kg. The starting dose may be increased by 1 to 2 mg/kg every 6 hours until the desired effect is achieved. Doses greater than 6 mg/kg are not recommended.
  • The recommended dose for treating hypertension is 40 mg twice daily. The dose of other blood pressure medications should be reduced by half when Lasix is added.

Thiazide diuretics

Thiazide diuretics may come in oral tablet form. For example, Thalitone (chlorthalidone) is a common thiazide diuretic.

  • The optimal dose of Thalitone varies greatly from patient to patient. For high blood pressure, the recommended dose range is 25 to 100 mg daily. Most patients receive 12.5 to 25 mg daily.
  • Edema is treated with 50 to 100 mg daily or 100 mg every other day and the maximum dose is 200 mg daily.
  • Heart failure is treated with 12.5 to 100 mg daily.

What drugs interact with Lasix and thiazide diuretics?


  • Administration of Lasix with aminoglycoside antibiotics (for example, gentamicin) or ethacrynic acid (Edecrin, another diuretic) may cause hearing damage.
  • Lasix competes with aspirin for elimination in the urine by the kidneys. Concomitant use of furosemide and aspirin may, therefore, lead to high blood levels of aspirin and aspirin toxicity.
  • Lasix also may reduce excretion of lithium (Eskalith, Lithobid) by the kidneys, causing increased blood levels of lithium and possible side effects from lithium.
  • Sucralfate (Carafate) reduces the action of Lasix by binding Lasix in the intestine and preventing its absorption into the body. Ingestion of Lasix and sucralfate should be separated by two hours.
  • When combined with other antihypertensive drugs, there is an increased risk of low blood pressure or reduced kidney function.
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) -- for example., ibuprofen, indomethacin (Indocin, Indocin-SR) -- may interfere with the blood pressure-reducing effect of Lasix.

Thiazide diuretics

  • Thiazide diuretics can lower potassium and magnesium blood levels since they are both eliminated in urine. Low levels of potassium and magnesium in the blood can result in abnormal heart rhythms, particularly in those who are also taking digoxin (Lanoxin) in addition to a thiazide.
  • Thiazide diuretics can increase the risk of lithium (Eskalith, Lithobid) toxicity by reducing the kidneys' ability to eliminate lithium in the urine.
  • Drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs) -- such as ibuprofen (Motrin), naproxen (Naprosyn), and nabumetone (Relafen) -- can reduce the effectiveness of thiazide diuretics in lowering blood pressure because they may reduce the ability of the kidneys to make urine, particularly in patients who have reduced kidney function.
  • People who have diabetes may have increased blood sugar levels when taking thiazide diuretics.
  • It is not recommended to use thiazide diuretics with dofetilide (Tikosyn), a drug used for treating abnormal heart rhythms, as this may increase the blood levels of dofetilide (Tikosyn) and cause abnormal heart rhythms.
  • Thiazide diuretics can reduce how the body responds to norepinephrine and render norepinephrine less effective.

Are Lasix and thiazide diuretics safe to use while pregnant or breastfeeding?


Thiazide diurectics

  • Thiazide diuretics including Thalitone (chlorthalidone) cross the placenta and can cause jaundice in the fetus or newborn. Therefore, thiazide diuretics such as Thalitone should not be used during pregnancy unless absolutely necessary.
  • Large doses of thiazide diuretics may suppress milk production, but the American Academy of Pediatrics considers thiazides to be compatible with breastfeeding.

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Lasix (furosemide) and thiazides are diuretics (water pills) used to treat excess accumulation of fluid or swelling of the body (edema) caused by heart failure, kidney disease, chronic kidney failure, or liver disease. Lasix and thiazide diuretics are also used to treat high blood pressure (hypertension).

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