Lasix Side Effects

Lasix Side Effects

Lasix is the brand name of the drug furosemide. It has a strong, rapidly occurring, short-term diuretic effect.

The diuretic effect of furosemide is due to its ability to inhibit reabsorption of chloride and sodium in the kidneys. The more ions there are in the lumen of the renal tubules, the more water enters there and the more urine is produced.

In patients with heart failure, the drug expands the veins and thereby reduces preload on the heart, lowers blood pressure in the pulmonary artery and the left ventricle (the effects are quite pronounced only with safe renal function).

In patients with hypertension, Lasix lowers blood pressure through rapid decrease in the volume of circulating blood in the body, strengthening of sodium excretion, and some reduction in the tone of the vascular wall.

When administered intravenously, the drug begins to act within 5 minutes and lasts for 2 hours.

When administered as a tablet, the medication starts to act within 1 hour, and lasts for approximately 7 hours.


  • Edema syndrome caused by various diseases (including nephrotic syndrome, portal hypertension syndrome, liver cirrhosis and chronic heart failure).
  • Chronic renal failure.
  • Acute renal failure (including ones induced by pregnancy and burn disease).
  • Cerebral edema.
  • Acute left ventricular failure (in pulmonary edema and cardiac asthma).
  • Arterial hypertension.

In addition, the drug is used in cases of poisoning by certain substances to quickly remove toxins from the body.

Side effects

Lasix sometimes causes adverse reactions from the cardiovascular system due to excessive decrease in blood pressure. There may be dizziness, weakness, drowsiness, headache, visual disorders, impaired concentration, slow reactions, dry mouth, precollaptoid state or fainting.

If these symptoms occur regularly, you need to see a doctor so that he can decide whether to reduce the drug dose.

Allergies when using Lasix are quite rare and may manifest in the form of skin itching, skin rash, hives, skin sensitivity to sunlight, purpura, exfoliative dermatitis, vasculitis, exudative erythema multiforme, necrotizing arteritis, fever and chills. Anaphylactic shock was extremely rare and occurred only after intravenous administration.

Rare side effects

In some cases, Lasix may cause the following adverse reactions:

  • Digestive system: constipation, diarrhea, nausea, or vomiting.
  • Nervous system: numbness, crawling or tingling sensations.
  • Sense organs: tinnitus and reversible hearing loss (more common in people with nephrotic syndrome and renal failure).

Serious side effects

The likelihood of most of the severe side effects developing when taking Lasix depends on the presence of certain comorbidities.

You need to seek emergency medical attention once any of the following conditions occurs:

  • Digestive system, rarely: acute pancreatitis, jaundice (due to intrahepatic cholestasis).
  • Hematopoietic system, rarely: hemolytic anemia (pale skin, weakness, dizziness, shortness of breath, yellow skin and sclera, heart palpitations, nausea, and vomiting), aplastic anemia (pale skin, weakness, shortness of breath, dizziness, palpitations, bleeding and infectious complication).
  • Urinary system (side effects occur if there is urine outflow obstruction, for example, as a result of kidney stones, hydronephrosis, narrowing of the urethra, prostate enlargement): painful urination, increase of the lower abdomen, pain in the lumbar region, or in the perineum, difficulty urinating, urinary retention, blood in the urine.
  • Metabolism: emergence of the symptoms of previously hidden diabetes (weakness, fatigue, weight loss, thirst, dizziness, poor wound healing), emergence or worsening of gout (due to increased concentration of uric acid in the blood).

Keep in mind that long-term use or use of high doses of Lasix due to loss of salt can lead to disruption of water-salt and acid-base metabolism. The symptoms of such disruptions may be headache, muscle weakness, seizures, confusion, irregular heartbeat, and digestive disorders. The likelihood of such adverse reactions occurring is increased in patients with significant comorbidities (for example, heart failure or cirrhosis of the liver), poor nutrition and uncontrolled use of other medicines.

Changes in laboratory parameters

There are rarely low platelet count, low white blood cell count and low agranulocytes count. Patients with aplastic anemia experience severe anemia, thrombocytopenia, leukopenia, and increased erythrocyte sedimentation rate (ESR). Except changes in the peripheral blood, patients with hemolytic anemia observe elevated levels of bilirubin.

In some cases, there may be elevated liver enzymes, elevated triglycerides and cholesterol, transient increase in urea and creatinine levels, as well as increased concentration of uric acid.

With the manifestation of diabetes, there is an increase in blood sugar levels.

Side effects in children

In prematurely born infants, Lasix may cause nephrocalcinosis (a disease in which calcium salts are deposited in the kidneys). In other cases, children have the same side effects as in adults.

Side effects in men

In separate cases, treatment with Lasix in men may cause reduced potency.

Side effects during pregnancy and breast-feeding

Lasix passes the placental barrier. The drug is contraindicated during pregnancy (particularly in the first half of pregnancy) and is prescribed only for emergencies and only for short periods. Possible side effects are the same as for the other categories of patients.

The drug is excreted in breast milk and may inhibit lactation. Lasix is not prescribed during breastfeeding.

Side effects in the elderly

The probability and severity of adverse reactions in the elderly depend on the presence and severity of comorbidities.

Bear in mind that significant fluid loss and decrease in the volume of circulating blood can cause blood clots thereby increasing the risk of thrombosis.

In the treatment of elderly patients, the dose is adjusted on individual basis by gradual increase. Treatment is conducted under the close supervision of a doctor.


Lasix overdose can be both acute (at a single intake of a high dose) and chronic (at a long-term treatment). There may be drop in blood pressure (to the extent of a shock in severe cases), weakness, nausea, vomiting, confusion, apathy, arrhythmia (to the extent of severe life-threatening arrhythmia), thirst, dry mouth, urinary retention, delirium, flaccid paralysis, thrombosis and acute renal failure.

You should seek immediate medical attention once these symptoms appear.

Warnings and recommendations

Before starting treatment, make sure that you do not have diseases that could interfere with the normal outflow of urine. Lasix is contraindicated for pronounced disturbances of urine outflow. Only the doctor can decide whether patients with partial violation of outflow of urine can take Lasix. Patients should be monitored throughout the course of treatment and especially at the initial stage of taking the drug.

Be sure to inform your doctor of the presence of comorbidities, especially diseases of the kidneys, heart, and liver, diabetes, gout, lupus, pancreatitis, and diseases associated with increased or decreased blood pressure.

Tell your doctor if you are planning to take any medicines during treatment with Lasix. This especially concerns cardiac glycosides, glucocorticosteroids, laxatives, antibiotics and antimicrobial agents, nonsteroidal anti-inflammatory medicines, drugs for lowering blood sugar levels, bronchodilators, cyclosporine, phenytoin, drugs for lowering blood pressure, and other diuretics.

Prior to treatment, be sure to tell your doctor about any allergies to any medications, especially Lasix, Furosemide and sulfonamides.

During treatment, follow the doctor’s instructions carefully and regularly do all the necessary tests – this will help prevent the development of side effects associated with violation of water-salt metabolism, changes in blood pressure, and impaired function of various organs.

Consult with your doctor and make sure you take plenty of fluids.

Try not to expose yourself to the sun for during treatment with Lasix, the skin can become more sensitive to the sun.

Try not to go out in the heat outside and avoid areas with high temperatures. When taking Lasix, the body adapts poorly to high ambient temperature. This therefore increases the likelihood of a heat stroke.

During the course of treatment, it is recommended to eat foods high in potassium (dried fruits, spinach, cauliflower, tomatoes, bananas, potatoes, lean meat).

If for some reason you lost a lot of fluid (due to diarrhea, vomiting or sweating), this should be reported to your doctor so that he can adjust the dose of the drug.

In no case should you arbitrarily increase the dose of Lasix. All decisions on changing the dosage of the drug should be taken only by the doctor.

If you have to be examined using X-ray contrast agent, be sure to inform your doctor that you are taking Lasix since the introduction of such a substance may increase the likelihood of impaired kidney function.

Some adverse reactions to Lasix (for example, excessive lowering of blood pressure) may affect attention concentration and reduce the speed of your reactions. Before driving, make sure there are no disorders that could affect your condition. You should be especially attentive at the beginning of treatment and when increasing the drug dose. During this period, it is better to refrain from driving.

Lasix and alcohol

Alcohol may increase the diuretic effect of Lasix and so taking alcohol should be abandoned during treatment.