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Lasix (Furosemide)

Lasix is principally used to treat excessive fluid retention associated with congestive heart failure, liver cirrhosis, and renal disease.

Last Modified: 13 May 2024

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What is Lasix? 

Lasix, commonly known by its generic name furosemide, is a potent diuretic (“water pill”) medication that promotes the excretion of excess fluid from the body by increasing urine production. It belongs to a class of drugs known as loop diuretics. 

Global Name

Generic name: Furosemide
Brand name: Lasix, Frumex, and Diuspec. 


What is Lasix used for? 

Lasix is principally used to treat excessive fluid retention associated with congestive heart failure, liver cirrhosis, and renal disease. It is also prescribed to manage hypertension (high blood pressure). 

How do you use Lasix? 


Lasix is available in tablet form, oral solution, and injectable form.

Dosage information: 

  • Adults with fluid/volume retention: Initial dose of 20 to 80 mg, which may be adjusted based on response. 
  • Adults with Hypertension: Typically, 40 mg once or twice daily, with adjustments as necessary. 
  • Children: Doses for children are based on weight, typically 1 to 2 mg/kg body weight. 


  • Children: Yes, with pediatric dosing. 
  • Adults: Yes. 
  • Elderlies: Yes, often starting at the lower end of the dosing range due to kidney function. 
  • Pregnancy and Lactation: Use only if the potential benefit justifies the potential risk to the fetus, and caution should be exercised when administered to a nursing mother. 

Is there anyone who can’t take Lasix? 

  • Individuals allergic to sulfonamides ("sulfa" drugs) or furosemide should not take Lasix. 
  • It is contraindicated in patients with anuria. 

Warnings and precautions:

  • Lasix should be taken in the morning to avoid disturbing sleep with the need to urinate. 
  • It should be taken as prescribed, with doses adjusted by a healthcare provider. 

Drug and Food Interactions 

  • Lasix can interact with a range of medications including aminoglycoside antibiotics, heart medications, and NSAIDs. 
  • Can have detrimental additive diuretic effects when taken together with sugary, caffeinated and alcoholic beverages. 

Side Effects

  • Common side effects include increased urination, dehydration, electrolyte imbalance, and dizziness. 
  • Severe side effects might include hearing damage, severe skin reactions, hypotension, cardiac arrhythmias or pancreatitis. 

Pharmacist Tips

Understanding Your Medication: 

  • Recognize that Lasix is not a medication to be taken on an "as needed" basis; follow your prescription schedule closely. 

Hydration and Diet: 

  • Maintain proper hydration but follow your doctor's advice if fluid intake needs to be restricted. 
  • Eat a potassium-rich diet or take supplements if recommended, as Lasix can deplete potassium levels. 

Monitoring and Follow-up: 

  • Regular monitoring of blood pressure, electrolytes, and kidney function is essential while taking Lasix. 
  • Report any symptoms of electrolyte imbalance, such as muscle cramps, weakness, or irregular heartbeats, to your healthcare provider. 

Avoiding Drug Interactions: 

  • Always inform your pharmacist about all the medications you are taking to avoid potential drug interactions. 

Lifestyle Considerations: 

  • Stand up slowly from sitting or lying down to prevent dizziness and falls caused by a sudden drop in blood pressure (orthostatic hypotension) . 

Storage and Handling: 

  • Store Lasix at room temperature away from moisture, heat, and light. 

Emergency Preparedness: 

  • Wear a medical alert tag or carry an ID card for quick reference in emergency situations stating that you take Lasix, as Lasix can  cause severe dehydration and electrolyte imbalance.. 

Travel Tips: 

  • When traveling, carry an adequate supply of Lasix, and keep it in its original labeled container to avoid customs issues. 

By adhering to these tips and consulting with your healthcare provider regularly, you can effectively manage your condition with Lasix. Your pharmacist is a valuable resource for any additional questions or concerns regarding your medication. 


Where is Lasix available in Hong Kong?

Lasix is a prescription medication that can be prescribed by healthcare providers.


Is Lasix for purchase over-the-counter? 

No, Lasix is a prescription medication and cannot be bought over-the-counter.

Can I take Lasix at night?

It is best to take Lasix in the morning to avoid disrupting sleep with frequent urination.

How quickly does Lasix work?

When taken orally, Lasix begins to work within an hour and lasts for about 6 to 8 hours. The injectable form works within minutes. 

How can Lasix cause renal failure?

Lasix, or furosemide, can lead to renal failure in some cases by causing decreased blood flow to the kidneys (through venodilation) and severe dehydration and electrolyte imbalances, potentially causing acute tubular necrosis secondary to hypoperfusion ischemia, especially with excessive diuresis. It is crucial to use this medication under medical supervision to prevent such adverse effects. 

This website provides content related to drug use and medicine for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Do not use the information on this website to diagnose or treat a health problem or disease without consulting a qualified healthcare provider. The website's owners and contributors are not liable for any repercussions, adverse effects, or consequences resulting from the use of any medication or information provided herein.

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