Furosemide (Lasix): Uses, Dosage, Side Effects and Precautions

Furosemide (Lasix) is a loop diuretic, often called a water tablet, used to treat fluid retention linked to heart failure, liver cirrhosis and kidney disease, and high blood pressure in adults. This guide covers furosemide uses, how it works, dosage, side effects, precautions, drug interactions, use in pregnancy and breastfeeding and its approximate price in India.

What is Furosemide?

Furosemide is a loop diuretic used to treat conditions involving excess fluid retention, such as heart failure, liver cirrhosis, and kidney diseases. It is also used to treat hypertension in adults. By increasing urine production, it helps remove excess salt and water from the body, thereby reducing symptoms of fluid overload. It is also known by the generic name frusemide.

How Furosemide Works

Furosemide works by inhibiting the Na-K-Cl symporter in the loop of Henle in the kidneys, which reduces the reabsorption of sodium and chloride. This leads to increased urination, helping to reduce excess fluid in the body.

When to Use Furosemide

Heart Failure: Reduces edema and fluid retention in the body.
 Hypertension: Helps lower blood pressure by reducing fluid volume. It is used in adults, alone or along with other blood pressure medicines.
 Kidney Disease: Treats fluid retention associated with kidney problems, including nephrotic syndrome.  Liver Cirrhosis: Treats edema associated with cirrhosis of the liver.

How to Take Furosemide

Furosemide comes as tablets or liquid. It is usually taken once a day at first, and some people may later need it twice a day. Try to take it at the same time every day, ideally in the morning. If you take it twice a day, the second dose is usually taken in the late afternoon. You can take it with or without food.

Your doctor may start with a low dose and increase it after a week or more. If you take it for a long time, for example for heart failure, your doctor may arrange regular blood tests. If you miss a dose, take it when you remember unless it is nearly time for the next one. Never take two doses together to make up for a missed dose.

Take this medicine only as advised by your doctor or healthcare professional. Do not start, stop, or change the dose on your own.

Furosemide Dosage

Adult dose for edema: The usual starting dose is 20 to 80 mg as a single dose. Your doctor may adjust it based on your response. In clinically severe edema, it can be carefully increased up to a maximum of 600 mg per day.
 Adult dose for hypertension: The usual starting dose is 80 mg per day, generally divided into 40 mg twice daily, and then adjusted according to response. When furosemide is added, your doctor may need to lower the dose of your other blood pressure medicines.
 Pediatric dose: The usual starting oral dose is 2 mg per kg body weight as a single dose. The doctor may increase it if the response is not enough, but doses above 6 mg per kg are not recommended.

The right dose depends on the condition being treated, age, weight, kidney and liver function, the form of medicine, other medicines and how well treatment is working.

Side Effects of Furosemide

Common side effects: Dehydration, low potassium levels, dizziness, low blood pressure. Some people also pass urine more often than usual, feel thirsty with a dry mouth, or get headaches and muscle twitches. If you feel dizzy or drowsy, do not drive or use machinery.

Serious side effects needing urgent medical attention: A severe allergic reaction (swollen throat or tongue, itchy raised rash, difficulty breathing). Blistering skin around the mouth, eyes, nose or genitals with flu-like symptoms. Lower back or side pain, fever, trouble passing urine or blood in urine, which may point to kidney problems. Severe dehydration, with very little or dark urine, dizziness, tiredness, sunken eyes or confusion. Hearing problems such as ringing in the ears or hearing loss are rare, and are linked mainly to high doses or rapid injection.

Who Should Not Take Furosemide

Furosemide should not be used by people who are unable to pass urine (anuria) or who have a history of hypersensitivity to furosemide.

Furosemide Precautions

Furosemide may not be suitable, or may need extra care, if you have had an allergic reaction or serious side effect with furosemide or another diuretic, kidney or liver problems, diabetes or Addison’s disease, gout, or low blood pressure. Tell your doctor about all your medical conditions before starting. If you have vomiting, diarrhoea or fever while taking furosemide, you are at higher risk of dehydration, so speak to your doctor or pharmacist for advice.

Furosemide in Pregnancy and Breastfeeding

Furosemide is not usually used during pregnancy or while breastfeeding. It may also reduce milk production. Tell your doctor if you are pregnant, trying to get pregnant or breastfeeding, so that a suitable treatment can be chosen.

Furosemide Drug Interactions

Some medicines and supplements may not mix well with furosemide. These include other blood pressure medicines (such as ACE inhibitors and beta blockers), heart rhythm medicines (such as digoxin and amiodarone), medicines or supplements that raise potassium levels, some NSAID painkillers, laxatives, fluconazole, some antidepressants and antipsychotics, and lithium. This is not a complete list. Tell your doctor or pharmacist about all prescription medicines, over-the-counter medicines, herbal products and supplements you use.

Food and Alcohol

You can eat normally, but check with your doctor how much fluid you should drink, because you need to avoid dehydration. It is best not to drink alcohol, as it can add to dizziness, light-headedness and dehydration.

Furosemide Brands, Strengths and Approximate Price in India

Common brands in India: Lasix, Furon. Lasix is available as a 40 mg tablet.
 Approximate price: Lasix 40 mg tablet, strip of 15 tablets, about ₹9 to ₹20. The actual price varies by brand, strength, pack size, pharmacy, city and date.

How HealthPil Can Help

Medicines should be started, adjusted, or stopped only under the guidance of a qualified healthcare professional. If you have questions about this medicine, its side effects, or your treatment plan, you can consult a doctor through HealthPil. HealthPil connects you to healthcare providers for proper diagnosis and treatment.