What You Need to Know About Lasix (Furosemide)
If you’re suffering from water retention or high blood pressure, your doctor may recommend a drug containing furosemide, also known as Lasix. Before you start taking this drug, you should learn everything about it you can.
What is Furosemide? What does it do?
Furosemide is a “loop diuretic,” a drug that causes the body to make more urine in a part of the kidney that causes the urine to be concentrated and water to be reabsorbed.1
Furosemide is used to reduce the swelling and fluid retention caused by various medical problems, including heart disease or liver disease, and to treat high blood pressure. It causes the kidneys to get rid of unneeded water and salt from the body into the urine.2
If the heart becomes less efficient at pumping blood around the body, fluid leaks out of the blood vessels causing swelling in the tissues of the lungs, feet and ankles. Furosemide prevents the build up of fluid by increasing the amount of urine produced by your kidneys, releasing more liquid from the body.3
Does Furosemide work?
A comparison of furosemide and two other loop diuretics, torsemide and bumetanide, found that all three decreased incidence of death and hospitalization in treating heart failure, but that the other two drugs performed better than furosemide and were safer for patients suffering heart failure. The report recommended torsemide over furosemide but stated that there was little evidence that either drug was better than furosemide in treating other fluid retention conditions.4
It should also be noted that furosemide is “off-patent” and the other drugs under comparison in the comparison above are drugs patented by the companies that sponsored the study. In these circumstances, the consultants hired by the drug companies have a significant incentive to find that the drugs still under patent (and can’t be manufactured by competitors) are more effective.
A review of nine trials of loop diuretics concluded that their benefit in lowering blood pressure was minimal and that had probably been overestimated in the studies due to a high risk of bias. The review also concluded that there was no “meaningful difference” between different loop diuretics in lowering blood pressure.5
What should I go over with my doctor before I decide to take furosemide?
Diuretics like furosemide work by targeting the body’s organs. Furosemide increases the body’s release of sodium, potassium, calcium, magnesium and other essential elements. The loss of these electrolytes is a major cause of toxicity effects alone and can aggravate the effects of other medications. For example, low potassium levels may increase the cardiac toxicity of digitalis.6
Because furosemide targets the function of the kidneys, patients at risk of abnormal kidney function, patients with kidney failure or patients with type 2 diabetes should be treated with caution. Any patient taking furosemide may suffer electrolyte depletion and dehydration, with symptoms of thirst, lethargy and confusion. In a hospital-based study, patients taking furosemide had a 21% rate of adverse affects. The most common adverse effects in this study were hypovolemia (decrease in blood volume), hyperuricemia (high level of uric acid in the blood, which can lead to gout) and hypokalemia (low potassium in the blood—too low can be fatal).7
Gastrointestinal bleeding has been reported in patients taking furosemide, especially in patients with lowered kidney function.
In children taking furosemide, adverse effects have included nephrocalcinosis (higher levels of calcium in the kidneys, which can lead to kidney failure) and kidney stones. Tachycardia (a very high heart rate) has been reported in treating infants with intravenous furosemide at high dose.
What if I’m already taking furosemide?
Never stop taking any prescription medication without talking to your doctor first. If you are already taking furosemide and are concerned about side effects, talk to your doctor.
Learn everything you can about furosemide before you start taking it.
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1 Generic Drugs, “”Frumex Generic” (retrieved 25 October 2012) http://www.igenericdrugs.com/?s=Frumex
2 PubMed Health, “Furosemide” (reviewed 1 September 2010, retrieved 25 October 2012)
3 Patient, “Furosemide” (retrieved 25 October 2012) http://www.patient.co.uk/medicine/furosemide
4 Ann Pharmacother., Wargo KA and Banta WM, “A comprehensive review of the loop diuretics: should furosemide be first line?” (November 2009), http://www.ncbi.nlm.nih.gov/pubmed/19843838
5 PubMed Health, “Loop diuretics cause modest blood pressure lowering” (10 July 2012), http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0012338/
6 National Institutes of Health Toxnet, “Furosemide” (retrieved 25 October 2012), http://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+3086
7 Ibid.
8 Ibid.
9 Ibid.