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Precautions and Warnings With Furosemide

It is important to be aware of the precautions and warnings with furosemide before starting the medication in order to minimize any risks. There are certain people who should not take furosemide, including those who are not producing any urine or are allergic to any of the components used to make furosemide. Other precautions and warnings with furosemide relate to the possibility of extremely low blood pressure, the risk of permanent hearing loss, and possible pregnancy risks.

Furosemide: What Should I Tell My Healthcare Provider?

You should talk with your healthcare provider prior to taking furosemide (Lasix®) if you have:
  • Liver disease, including cirrhosis
  • Kidney disease or kidney failure
  • Diabetes
  • Systemic lupus erythematosus (lupus or SLE)
  • Gout
  • Fluid or electrolyte problems
  • Difficulty passing urine 
  • Any allergies, including allergies to sulfa drugs, foods, dyes, or preservatives.
Also, let your healthcare provider know if you:
Tell your healthcare provider about all of the medicines you are currently taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.

Some Precautions and Warnings With Furosemide

Some furosemide warnings and precautions to be aware of include:
  • Furosemide should be started cautiously to treat cirrhosis or ascites (fluid retention in the abdominal cavity). In general, furosemide should be started in the hospital for these people, so that they can be monitored closely.
  • If kidney problems seem to be getting worse (especially for those with very severe kidney disease), furosemide should be stopped because furosemide can make kidney problems worse.
  • Furosemide can cause hearing loss. Sometimes this hearing loss is permanent. It is more common when high doses of furosemide are given intravenously or when the drug is combined with other medications that can cause hearing loss.

People with kidney disease may also be at a high risk for this problem. Let your healthcare provider know right away if you notice hearing loss or ringing in the ears (tinnitus).


  • People who are allergic to sulfonamides ("sulfa" drugs) may also be allergic to furosemide.
  • Furosemide may cause extremely low blood pressure in some people. Extremely low blood pressure is more likely to happen when the medicine is first started or when the dosage is changed. It is also more likely to happen in people who are on dialysis, who have congestive heart failure, who have diarrhea or vomiting, or who have excessive sweating. This is why it is important to drink fluids regularly while taking furosemide. If you have any possible symptoms of low blood pressure (such as dizziness, lightheadedness, or fainting), contact your healthcare provider. If you have fainted, stop taking furosemide until you have talked to your healthcare provider. 
Also, make sure not to drive, operate any heavy machinery, or perform any other tasks that require alertness until you know how furosemide affects you.
  • Furosemide may affect electrolytes in the blood (including sodium, calcium, potassium, magnesium, and chloride). Therefore, your healthcare provider will regularly check these levels. If you notice any symptoms of a possible electrolyte imbalance, contact your healthcare provider. These symptoms may include:


    • Dry mouth
    • Thirst
    • Weakness
    • Lethargy
    • Drowsiness
    • Restlessness
    • Muscle pain or muscle cramps
    • Low blood pressure (hypotension)
    • Decreased urination
    • A rapid heart rate (tachycardia) or irregular heart rhythms (arrhythmia)
    • Nausea or vomiting.


  • Furosemide is also known to worsen gout.


  • Furosemide can cause kidney stones or calcium deposits in the kidneys. This seems most likely to occur in children, especially premature babies. Extra kidney monitoring is necessary when this drug is used in children.


  • Furosemide has been reported to worsen systemic lupus erythematosus or, in some cases, to even to cause the condition.
  • Furosemide may cause high blood sugar (hyperglycemia) in diabetics or, in some cases, even cause diabetes in people without a history of the condition.


  • Furosemide should be used with caution in people with difficulty passing urine due to an enlarged prostate or bladder problems. Because Lasix increases urine production but does not help with the difficulty passing urine, it may cause acute urinary retention, which is a medical emergency.


  • Furosemide is considered a pregnancy Category C medication. This means that furosemide may not be safe to use during pregnancy. Talk to your healthcare provider about the risks and benefits of using furosemide during pregnancy (see Lasix and Pregnancy for more information).
  • Furosemide passes through breast milk. Therefore, if you are breastfeeding or plan to start breastfeeding, be sure to talk with your healthcare provider about using furosemide (see Lasix and Breastfeeding for more information).
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