Furosemide is a powerful diuretic that is often prescribed to treat high blood pressure, heart failure, and other medical conditions. While furosemide can be a lifesaving medication for some people, it can also cause serious side effects if not taken correctly. In this blog post, we will discuss the furosemide warnings you need to know before taking this medication.

Important warnings

FDA warning: Dehydration risk

  • A black box warning is on this drug. This is the FDA’s most severe caution, known as a black box warning. A black box warning informs doctors and patients about the possible harmful effects of medication.
  • Furosemide is a strong diuretic (water pill) that helps your body get rid of excess water. It does this by increasing the amount of urine your body makes. If you take too much of this drug, it can lead to very low amounts of water and electrolytes in your body. This can cause dehydration. Your doctor will monitor your fluid levels and may change your dosage based on those levels.
  • Low blood pressure warning: This drug can cause low blood pressure. Symptoms include feeling dizzy and faint after standing up. If this occurs, move slowly when changing positions after sitting or lying down. If this problem continues, call your doctor.
  • Low potassium levels warning: The major concern with this drug is that it can cause low potassium levels. (Potassium is a mineral that aids in the functioning of your nerves, muscles, and organs.) Tiredness, muscle weakness, and nausea or vomiting are possible symptoms. If you experience any of these symptoms, please contact your doctor immediately.
  • Low thyroid levels warning: High doses (more than 80 mg) of furosemide can suppress the thyroid gland. If you’re taking high dosages of this drug and experience thyroid abnormalities, contact your doctor right away. These symptoms include:
  • tiredness
  • weakness
  • weight gain
  • dry hair and skin
  • increased feelings of being cold

What is furosemide?

Furosemide (Lasix) is a prescription drug that comes in the form of Lasix. It’s also available as a generic medicine. Generic medicines are generally less expensive. In some situations, they may not be accessible in all potency or shapes as the brand-name variant.

Why it’s used

Furosemide is a diuretic (a medication that causes the kidneys to excrete excessive water) that is used to treat high blood pressure and edema. It’s also used to treat edema. This is a condition in which the body floods with fluid due to the accumulation of fluids in the body. Edema can be caused by various medical conditions such as heart failure, liver cirrhosis, or renal disease.

Furosemide is a diuretic that is used to treat high blood pressure. This implies that you may need to take it in conjunction with other medicines.

How it works

Furosemide is a diuretic and belongs to the group of medications known as diuretics. A class of drugs is a collection of medicines that have similar effects. These medicines are frequently used to treat a variety of illnesses.

Furosemide causes your body to eliminate extra salt and water by aiding the renal tubular transport system. It accomplishes this by increasing the amount of urine produced by your body. This can help reduce blood pressure and edema.

Furosemide side effects

Certain adverse effects of furosemide can occur when taken by mouth.

More common side effects

The more common side effects that can occur with furosemide include:

  • nausea or vomiting
  • diarrhea
  • constipation
  • stomach cramping
  • feeling like you or the room is spinning (vertigo)
  • dizziness
  • headache
  • blurred vision
  • itching or rash
  • increased urination

If the symptoms are minor, they will generally go away within a few days or weeks. If the effects become more severe or don’t go away, consult with your doctor or pharmacist.

Serious side effects

If you have severe negative effects, call your doctor right now. If you believe you’re experiencing a medical emergency, dial 911. The following are some of the most serious side effects and their signs:

  • Excessive loss of water and electrolytes. Symptoms can include:
  • dry mouth
  • feeling of thirst
  • weakness
  • drowsiness
  • restlessness
  • muscle pains or cramps
  • urinating less
  • fast or abnormal heartbeat
  • severe nausea or vomiting
  • Low levels of thyroid hormones. Symptoms can include:
  • tiredness
  • weakness
  • weight gain
  • dry hair and skin
  • increased feelings of being cold
  • Pancreatitis (inflammation of the pancreas). Symptoms can include:
  • pain when you eat or drink
  • severe nausea or vomiting
  • fever
  • Liver damage. Symptoms can include:
  • yellowing of your skin
  • yellowing of the whites of your eyes
  • Hearing loss or ringing in your ears (can be temporary or permanent)
  • Blistering or peeling skin
  • Orthostatic hypotension (low blood pressure that happens when you stand up)
  • Allergic reaction
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Our mission is to provide you with the most up-to-date and useful information possible. However, because medicines impact individuals differently, we cannot promise that this data includes all possible adverse effects. This material is not meant to be a substitute for professional medical advice. Always talk about any potential side effects with your doctor, who is familiar with your medical history.

What should be considered before taking furosemide oral tablets?

drug interactions

Before starting furosemide, talk to your doctor about all of your medical issues and any medications you’re taking. These and other factors are addressed further down.


Interactions between medications, vaccines, foods, and other things may alter how a drug functions. Interactions are the effects of such interactions.

Before taking furosemide tablets, tell your doctor about all medicines you take, including prescription and OTC treatments. Also let them know if you use any vitamins, herbs, or supplements. Your doctor or pharmacist can inform you of any possible interactions that these items might have with furosemide oral tablets.

Interactions with drugs or supplements

Furosemide oral tablets can react with a variety of medicines. These medications include:

  • the seizure drug called phenytoin
  • certain antibiotics, such as neomycin, gentamicin, vancomycin, amphotericin B, and tobramycin
  • the cancer drugs cisplatin and methotrexate
  • diuretics other than furosemide, such as ethacrynic acid
  • angiotensin-converting enzyme inhibitors, such as benazepril, captopril, enalapril, and lisinopril
  • angiotensin II receptor blockers, such as candesartan, losartan (Cozaar), and irbesartan (Avapro)
  • the mental health condition drug lithium
  • the immunosuppressant drug cyclosporine
  • aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), such as indomethacin
  • thyroid hormone medications such as levothyroxine
  • the heart medication digoxin

This list does not cover all types of medications that may operate together. Your doctor or pharmacist can explain any additional interactions and those that might occur while taking furosemide oral tablets to you in further detail.

Other interactions or foods to avoid

There are no specific foods to avoid when taking furosemide. However, your doctor may advise you to limit the amount of salt in your diet. This is because high salt intake can contribute to edema formation in the body. And this can make it more difficult for furosemide to operate.

Salt levels in processed foods might be high. As a result, furosemide should not be taken along with these foods. Potato chips, salted nuts, and lunch meat are all examples of manufactured products.

Your doctor may be able to provide you with additional information on what foods to avoid for your condition. Inquire your doctor regarding the finest diet for your condition.


Furosemide oral tablets may not be appropriate for you or might be contraindicated if you have any pre-existing medical conditions or other circumstances that influence your health.

Contraindications are factors that raise the risk of adverse effects when taking a medicine. Furosemide should not be used in individuals who have experienced an allergic reaction to furosemide or are suffering from anuria. (Your body does not produce urine with anuria.)

Before you take furosemide oral tablets, talk to your doctor about your health history. Before taking this medicine, consider the following aspects.

  • Allergic reaction to sulfonamide (sulfa) drugs. You may be allergic to furosemide if you are sensitive to sulfa drugs. If you’ve ever experienced an adverse reaction to any other medicines, tell your doctor. You can’t take furosemide if you have a sulfa sensitivity.
  • Allergic reaction to furosemide. If you’ve had an adverse reaction to furosemide oral tablets or any of their components, do not take them. Inquire with your doctor about alternative treatments that are better for you.
  • Dehydration. Furosemide is a strong diuretic (water pill). It aids in the removal of extra fluids from the body. Taking too much furosemide, on the other hand, might result in dehydration (low fluid volume) and electrolyte abnormalities. These situations can be fatal. If you have electrolyte abnormalities or are at risk of dehydration, you’re more likely to experience this negative effect if you take furosemide. Your doctor will examine how you respond after you’ve taken the medicine. This will allow them to avoid any problems with dehydration by avoiding them. They’ll also give suggestions for reducing dehydration.
  • Kidney problems. Furosemide can sometimes cause your body to take longer than usual to eliminate the drug, which can lead to more serious side effects. This might enhance the medication’s effect and result in dangerously low blood pressure and other dangerous complications. Your doctor may prescribe a dosage of the drug that is lower to see how you respond. If you have severe renal disease, furosemide isn’t likely to be appropriate for you. Your doctor will go over this with you in further detail.
  • Liver problems. If you have severe liver problems, such as cirrhosis, furosemide may be given to you in the hospital. This is due to the fact that low electrolyte levels brought on by furosemide might increase your chance of serious liver damage. While receiving furosemide, your doctor will closely watch for dangerous side effects. If you have issues with your liver, contact your doctor immediately. They’ll let you know whether furosemide is okay for you to take and how it should be administered.
  • Diabetes. If you have diabetes, furosemide can make it more difficult to manage your disease. If you take any medications, tell your doctor so they may adjust your dosage. If you require the usage of furosemide, your doctor may advise you to pay closer attention to your blood sugar levels than usual.
  • Thyroid problems. Taking high dosages of furosemide may exacerbate thyroid problems. If you have a thyroid condition, speak with your doctor about whether furosemide is suitable for you. They can evaluate if furosemide is appropriate for you.
  • Bladder problems. Furosemide can cause urinary retention or prostatic hyperplasia (trouble emptying your bladder) if you have a bladder problem. Prostate hyperplasia and urinary retention are examples of these diseases. Before taking furosemide, inform your doctor if you have any problems with your bladder. If you have anuria, furosemide is not a good idea for you. Furosemide is contraindicated in people who have anuria.
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Furosemide oral tablets and alcohol

While drinking alcohol while taking furosemide might aggravate certain adverse effects of the medication. Low blood pressure, dizziness, and the potential for falls are all possible consequences.

If you consume alcohol, talk to your doctor about the amount that is safe to drink while taking furosemide. Remember that drinking alcohol can make your liver disease worse in some cases. (Furosemide is sometimes given to patients with liver problems.)

Pregnancy and breastfeeding

It’s unclear whether furosemide is OK to take during pregnancy. If you’re pregnant or intend to conceive, talk with your doctor about this. This medication should only be used if the benefits outweigh the risks.

Use of furosemide is not recommended if you’re breastfeeding due to nursing concerns. The medicine can enter the breast milk and result in serious side effects for a child who is fed via the breast.

Your doctor will be able to tell you more about the safety of furosemide use during pregnancy or while breastfeeding.

What are furosemide oral tablets used for?

Your doctor may talk to you about furosemide if you have high blood pressure (hypertension) or edema (fluid accumulation).

It’s a prescription drug that’s used to:

  • Lower high blood pressure in adults. It may be used alone or in combination with other blood pressure medications for the treatment of high blood pressure. Furosemide isn’t generally given as first-choice therapy for high blood pressure on its own. Usually, various medicines are tried before furosemide is employed.
  • Manage edema in adults and children. It’s employed for this purpose in individuals with edema who have:
  • congestive heart failure
  • kidney disease
  • cirrhosis (scarring in the liver)

Furosemide is a diuretic, which means it works by forcing your kidneys to eliminate extra fluids from your body. It treats edema and high blood pressure by draining excess water from your body through your kidneys.

Your doctor can give you more information about the advantages and disadvantages of furosemide for these applications.

Warnings for people with certain health conditions

For people with kidney problems: The drug is excreted through the kidneys. If you have kidney issues, more of the medication may stay in your system for a longer period of time. This can cause serious side effects, including blood pressure that is dangerously low. Your doctor may prescribe a lower dose of this medicine to begin with. To ensure that furosemide is safe for you to take, your doctor might also check how effectively your kidneys are working.

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For people with liver problems: If you have liver issues such as cirrhosis or ascites, furosemide should be given in the hospital. Furosemide may cause dangerously low electrolyte levels, which can lead to severe liver damage and brain function loss. (Electrolytes are minerals that help manage your body’s fluid balance and perform other vital tasks.) You will be closely monitored by your doctor.

For people with diabetes: Furosemide can make it more difficult to keep your blood sugar (glucose) levels under control. Make sure your doctor is aware of your diabetes before using this medicine.

For people with bladder disorders: If you have trouble emptying your bladder completely, furosemide might make things worse. Make sure your doctor is aware of your urinary issue before taking this medication.

For people with thyroid problems: High dosages (more than 80 mg) of furosemide can cause low thyroid hormones. Before you start taking furosemide, be sure to tell your doctor about any thyroid issues you may have.

Warnings for other groups

For pregnant women: Furosemide is a category C procreative drug. It implies two things:

  1. When a woman takes prednisone, it has been linked to negative consequences for her kid.
  2. Because no human studies have been done, it is uncertain how the medication will impact a fetus.

If you’re pregnant or think you could be, talk to your doctor. This medication should only be utilized if the possible advantage justifies the potential risk to the fetus.

For women who are breastfeeding: Furosemide can enter the breast milk and has the potential to produce life-threatening side effects in a breastfeeding infant. It also has the ability to reduce your body’s production of milk. If you’re breastfeeding, let your doctor know. You’ll need to decide whether or not to continue nursing or take this medication.

For children: Furosemide, like other loop diuretics, can cause kidney damage in infants and children less than 4 years old. It might promote the formation of kidney stones and calcium deposits in the kidneys. If furosemide is used to treat preemies before they are born, their risk of lung and heart problems increases.


Who should not use furosemide?

Furosemide is not for everyone. You should avoid furosemide if you:

  • are allergic to furosemide or other sulfa medications
  • currently have low blood pressure (hypotension)
  • already take ethacrynic acid, a different type of diuretic medicine that can cause the same side effects as furosemide
  • have liver disease, such as cirrhosis or ascites
  • have diabetes and are taking insulin to control your blood sugar levels
  • have a bladder disorder that makes it difficult to empty your bladder completely
  • have a thyroid problem

Is 20 mg of furosemide a lot?

Furosemide is available in tablet or liquid form. The furosemide dose your doctor recommends will be based on the following:

  • the condition being treated and its severity
  • other medical conditions you have (such as kidney disease, diabetes, liver disease)
  • how you respond to furosemide. Some people may need a high furosemide dose, while others may only need a low dose.
  • generally start with a low furosemide dose and increase the dosage if needed. The maximum furosemide dose is 80 mg per day.

What are the most common side effects of furosemide?

The most common furosemide side effects are:

  • thirst
  • dizziness
  • lightheadedness
  • headache
  • weakness
  • fatigue

Can furosemide cause hypokalemia?

Yes, furosemide can cause hypokalemia (low potassium levels). This may happen if you take furosemide for an extended period of time or if you take high doses. Symptoms of hypokalemia include:

  • muscle weakness
  • tingling in your hands and feet
  • extreme thirst
  • irregular heartbeat.

Can you crush a Lasix?

Yes, furosemide can be crushed. Talk to your doctor or pharmacist about the best way to take furosemide for you. It’s generally fine to crush furosemide tablets and sprinkle them into a spoonful of applesauce. You should swallow this mixture right away without chewing it. Then drink water immediately.

Conclusion thoughts

Furosemide is a powerful diuretic that can have serious side effects if not taken as prescribed. It’s important to understand the warnings and possible risks before taking furosemide and to consult with your doctor if you have any questions or concerns.

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