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Furosemide side effects and how to avoid them

Furosemide is a diuretic that treats edema and hypertension but can produce side effects. Check out our list of common and serious side effects.
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By | Apr. 27, 2021 Medically reviewed by Anne Jacobson, MD, MPH
Prescription pad with pill bottle representing Furosemide side effects information

Key takeaways

  • Furosemide is a diuretic used to treat edema and hypertension but can lead to both common and serious side effects, including electrolyte imbalance and severe dehydration.

  • The medication works by increasing the excretion of water and salt through urine. Because it works on one specific area of the kidneys, it can be used by people with kidney problems.

  • Common side effects include low electrolytes, dizziness, and increased urination, among others. Serious side effects of furosemide may require hospital treatment and can include pancreatitis, hearing loss, and life-threatening conditions like hepatic encephalopathy.

  • To reduce the risk of side effects, patients should inform their healthcare provider about all medical conditions and medications, follow dosing instructions carefully, and monitor for signs of dehydration or electrolyte imbalance.

Furosemide side effects | Serious side effects | How long do side effects last? | Warnings | Interactions | How to avoid side effects

Furosemide (brand name: Lasix) is a generic prescription diuretic that treats edema (fluid retention) due to congestive heart failure, cirrhosis of the liver, or kidney disease. Furosemide also treats hypertension (high blood pressure) and pulmonary edema (fluid in the lungs). 

Furosemide increases the amount of water and salt excreted in the urine, reducing fluids in the body’s tissues as well as in the bloodstream. As a loop diuretic, furosemide works on one particular anatomical area in the kidneys, making it effective in people with impaired renal function. 

Like all diuretics, furosemide can produce side effects, interact with other drugs, and worsen existing medical conditions. 

RELATED: Learn more about furosemide

Common side effects of furosemide

Furosemide has some side effects that can affect one or more systems in the body. The most common temporary side effects include:

  • Increased urination
  • Low electrolyte levels (low sodium, magnesium, calcium, or potassium levels)
  • Dizziness
  • Nausea
  • Vomiting
  • Diarrhea
  • Abdominal cramps
  • Loss of appetite
  • Sudden drop in blood pressure when standing up (orthostatic hypotension)
  • Muscle cramps
  • Weakness
  • Numbness
  • Ringing in the ears
  • Headache
  • Blurred vision
  • Elevated blood sugar levels (hyperglycemia)
  • Elevated cholesterol and fats (triglycerides) in the blood
  • Excess uric acid (hyperuricemia)
  • Increased liver enzymes
  • Injection site pain (when given furosemide injection)
  • Rash or itching 
  • Sensitivity to light (photosensitivity)

Serious side effects of furosemide

Furosemide has several serious and potentially hazardous side effects. These include:

  • Dehydration
  • Severe electrolyte depletion
  • Low blood volume (hypovolemia)
  • Elevated blood pH (metabolic alkalosis)
  • Ear damage (ototoxicity) and loss of hearing
  • Decline or loss of brain function due to liver dysfunction (hepatic encephalopathy) in people with liver disease
  • Swelling of the pancreas (pancreatitis)
  • Jaundice
  • Blood disorders including anemia, aplastic anemia, hemolytic anemia, agranulocytosis, eosinophilia, thrombocytopenia, and leukopenia
  • Severe allergic reactions such as anaphylaxis, severe skin reactions, and swollen blood vessels (systemic vasculitis) 

RELATED: Lasix side effects and how to avoid them

How long do furosemide side effects last?

Many of furosemide’s minor side effects, such as increased urination or digestive system problems, get better as the drug wears off, typically in six to eight hours. Other problems such as dehydration, electrolyte imbalance, hyperglycemia, elevated cholesterol, and mild allergic reactions take longer to resolve and may possibly require treatment. 

Some serious side effects such as pancreatitis or blood disorders may require hospital treatment. Hearing loss and tinnitus may be reversible when furosemide is discontinued, but may turn out to be permanent conditions in some people. Hepatic encephalopathy is a potentially life-threatening side effect that requires hospitalization and persists for an average of 48 hours. Hepatic encephalopathy is a reversible condition, but the survival rate is low. 

Furosemide contraindications & warnings

Furosemide may not be suitable for everyone. Misuse, overdose, and changes in existing medical conditions are all factors in determining the safety of this medication.

Abuse and dependence

Furosemide does not cause physical or psychological dependence. Furosemide may, however, cause temporary withdrawal symptoms when discontinued. Furosemide changes the body’s hormonal mechanism for regulating urination (diuresis), called the renin-angiotensin-aldosterone system, or RAAS. When furosemide is taken over the long-term and abruptly discontinued, the body overcompensates by retaining too much water and salt, causing fluid build-up or high blood pressure. The effects wear off in a few days, but people with serious heart disease may require monitoring during this period.

Overdose

A furosemide overdose will cause rapid diuresis (water elimination) resulting in dehydration and electrolyte depletion. Symptoms include extreme thirst, feeling hot, weakness, sweating, or fainting. An overdose also raises the risk of hearing loss. If an overdose is suspected, immediately go to an emergency room.

Restrictions

Furosemide is FDA-approved for use in a wide range of people, from premature newborns to people of advanced age. Because of the potential for dehydration and electrolyte depletion, everyone taking furosemide will be monitored for fluid volume and electrolyte levels. A healthcare provider will teach patients the signs of dehydration or electrolyte depletion. Potassium supplements may be recommended to prevent low blood potassium (hypokalemia).

Furosemide is never given to people:

  • Whose kidneys do not produce urine (anuria)
  • Who have had a serious allergic reaction to the drug

Furosemide is used with caution for certain age groups or medical conditions:

  • Premature newborns may require monitoring because of the risk of kidney stones (nephrolithiasis) or calcium deposits in the kidneys (nephrocalcinosis).
  • People older than 65 may be started at the lowest possible dose and monitored regularly.
  • People with a history of heart arrhythmias should be monitored.
  • People with kidney problems (renal impairment) or liver problems may be given smaller doses and monitored regularly.
  • People with urinary retention problems can see their symptoms worsen because of the increase in urine volume in the bladder.
  • Furosemide may be less effective and more likely to cause hearing loss in people with nephrotic syndrome.
  • People with diabetes will be warned about possible increases in blood sugar. They may be asked to monitor blood sugar levels regularly.
  • People with gout may see their symptoms worsen. Uric acid levels in the blood may need to be monitored.
  • Furosemide may activate or worsen lupus. 

Furosemide has not been determined as safe to take while pregnant or breastfeeding. Doctors are advised to carefully monitor fetal growth in women taking furosemide. Caution will also be required when taking furosemide while nursing. Furosemide both passes into breast milk and reduces lactation. In all cases, a doctor will carefully outline the risks and benefits of taking furosemide while pregnant or nursing. 

Furosemide interactions

Some prescription and over-the-counter (OTC) drugs have significant interactions with furosemide. A doctor, pharmacist, or healthcare provider will be well-versed in these drug interactions and be able to prepare people for possible drug interactions. 

Because of drug interactions, furosemide is never used with desmopressin or Marplan (isocarboxazid). Combining furosemide with desmopressin could cause dangerously low sodium levels, while isocarboxazid and furosemide may result in dangerously low blood pressure.

Other drug interactions will require caution and careful monitoring. These medications include:

  • Laxatives, corticosteroids, proton-pump inhibitors, and bronchodilators (beta-2 agonists): Combining furosemide with any of these medications will raise the risk of dehydration and electrolyte imbalances. 
  • Aminoglycoside antibiotics: Combining furosemide with other ototoxic drugs increases the risk of ear damage and hearing loss. 
  • NSAIDs (nonsteroidal anti-inflammatory drugs) and salicylates
  • Platinum-based cancer drugs: Combining furosemide with drugs like cisplatin or carboplatin increases the likelihood of those drugs damaging the kidneys, bone marrow, or ears. 
  • Blood pressure drugs: Combining furosemide with other drugs that lower blood pressure could cause dangerously low blood pressure (hypotension). 
  • Antipsychotics, sedatives, barbiturates, opioids, and erectile dysfunction medications: Combining these drugs with furosemide increases the risk of hypotension, so people with low blood pressure may have to be regularly monitored or doses modified.

How to avoid furosemide side effects

Furosemide is often given intravenously in hospitalized patients, but most people will take the medicine as a tablet or oral solution one or more times per day. There is no limit on the length of time furosemide can be taken, but people regularly taking furosemide should follow a few tips to help manage side effects.

1.  Tell the doctor about all medical conditions and medications

Before furosemide is prescribed, tell the prescribing doctor or healthcare professional about:

  • All current medical conditions, particularly kidney disease, liver disease, urination problems (such as enlarged prostate or bladder obstruction), gout, lupus, diabetes, electrolyte imbalances, heart arrhythmias, low blood pressure, or allergies to sulfonamides (sulfa drugs)
  • Pregnancy, breastfeeding, or any pregnancy plans
  • Any forthcoming glucose blood test 
  • Any forthcoming medical scan that will include radioactive contrast dyes
  • Any forthcoming surgery
  • All OTC and prescription drugs, supplements, and herbal remedies being taken, particularly desmopressin or Marplan (isocarboxazid) 

2. Take furosemide as directed

Follow all the directions on the prescription label or provided by a healthcare professional. Do not take more or less than prescribed until you’ve consulted with a doctor or healthcare professional. 

3. Avoid becoming dehydrated or low on electrolytes

Furosemide can cause fluids and electrolytes in the body to drop too low. Severe dehydration can cause kidney damage and circulatory collapse. Electrolyte depletion can escalate into serious problems including coma, seizures, and heart attack. Ask a healthcare professional how much and what kind of fluids can be taken after a dose of furosemide. Potassium or other supplements might also be needed.

When taking furosemide, be on the lookout for signs of dehydration such as dry mouth, dry eyes, muscle cramps, muscle pain, drowsiness, fatigue, and weakness. You may be able to drink liquids to resolve the problem, but if liquids are restricted, call a healthcare professional for medical advice.

4.  Monitor effects

Some people may be asked to monitor their medical conditions such as blood pressure or blood glucose levels. Check these values faithfully and record them in a medication diary. If the values are abnormal, call a doctor or other healthcare provider for help.

5.  Avoid NSAIDs and laxatives

Popular pain-relievers such as aspirin and ibuprofen can reduce the effectiveness of furosemide and increase the risks to the kidney or hearing. The same applies to bismuth subsalicylate, the active ingredient in Pepto-Bismol. It’s related to aspirin and will cause the same problems when combined with furosemide. 

Laxatives increase water loss, so they increase the risk of dehydration, electrolyte depletion, and kidney damage when taking furosemide. Talk to a doctor or other healthcare professional before taking any of these OTC drugs while taking furosemide.

6.  Stand up slowly

If standing up causes dizziness, try standing up slowly. Dizziness may require sitting back down for some time. Lie down if dizziness gets too bad.

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