Blood Pressure Home > Lasix Warnings and Precautions

There are many important Lasix warnings and precautions to be aware of, including the possibility of extremely low blood pressure, the risk of hearing loss, and possible pregnancy risks. You should not take Lasix if you are allergic to any of the ingredients used to make the medication or if you are not producing any urine. Prior to taking Lasix, be sure to tell your healthcare provider if you have liver or kidney disease, diabetes, or any allergies.

Lasix: What Should I Tell My Healthcare Provider?

You should talk with your healthcare provider prior to taking Lasix® (furosemide) 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 Lasix Warnings and Precautions

Some Lasix warnings and precautions to be aware of include:
  • Lasix should be started cautiously to treat cirrhosis or ascites (fluid retention in the abdominal cavity). In general, Lasix 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), Lasix should be stopped because Lasix can make kidney problems worse.
  • Lasix can cause hearing loss. Sometimes this hearing loss is permanent. It is more common when high doses of Lasix are given intravenously or when 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).
  • There are a number of medicines that Lasix can interact with (see Lasix Drug Interactions).
  • People who are allergic to sulfonamides ("sulfa" drugs) may also be allergic to Lasix.
  • Lasix 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 Lasix.

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 Lasix 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 Lasix affects you.
  • Lasix 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:


    • A 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.


  • Lasix is also known to worsen gout.
  • Lasix has been reported to worsen systemic lupus erythematosus or, in some cases, to even to cause the condition.


  • Lasix 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.


  • Lasix may cause high blood sugar (hyperglycemia) in diabetics or, in some cases, even cause diabetes in people without a history of the condition.


  • Lasix can cause kidney stones or calcium deposits in the kidneys of premature infants. Extra kidney monitoring is necessary when this drug is used in premature babies. 


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