furosemide at a glance
Medicine class
Loop diuretic (water tablet).
Main effect
Makes the kidneys excrete more salt and water, increasing urination.
Available forms
Selected UK products include tablets, oral solutions and injections or infusions.
What is furosemide used for?
Licensed uses vary by product and formulation. Principal UK indications across the selected products include:
Oedema associated with heart disease, including heart failure.
Pulmonary oedema or other fluid accumulation involving the lungs.
Oedema or ascites associated with liver disease.
Oedema associated with kidney disease, including nephrotic syndrome in some products.
Peripheral oedema associated with venous insufficiency or mechanical obstruction.
Hypertension; depending on the product licence, injectable products may be used when oral treatment is not feasible or a rapid effect is required.
How does furosemide work?
Furosemide blocks sodium and chloride reabsorption in the kidney’s ascending loop of Henle. Salt and water are then passed in the urine, reducing excess body fluid and circulating volume. Loss of potassium, magnesium and calcium may also increase.
furosemide preparations and strengths
Solution for infusion
Route: Intravenous
Strengths: 10 mg/mL
Oral solution
Route: Oral
Strengths: 4 mg/mL, 8 mg/mL, 10 mg/mL, 20 mg/5 mL, 40 mg/5 mL, 50 mg/5 mL
How to take furosemide
Follow the label and instructions for the specific product supplied.
Swallow tablets with water. Oral furosemide can be taken with or without food.
Measure oral solution with the supplied syringe or measuring device. Some solutions must not be mixed into food or drinks; check the leaflet.
Injection or infusion is administered by a healthcare professional.
Seek advice if vomiting, diarrhoea or fever develops because fluid loss can increase dehydration risk.
furosemide side effects
Common or expected effects
- Passing urine more often or urgently
- Thirst or dry mouth
- Dizziness or light-headedness
- Headache
- Muscle twitching or cramps
Get urgent medical advice
- Swelling of the mouth, tongue or throat, breathing difficulty or collapse
- A painful, blistering or peeling rash, particularly around the mouth, eyes or genitals
- Severe dehydration, confusion, fainting or markedly reduced urine output
- Side or back pain with fever, difficulty urinating or blood in the urine
- Palpitations, profound weakness or confusion that could indicate a serious electrolyte disturbance
- New tinnitus or hearing loss, particularly during injectable treatment
furosemide in pregnancy
Furosemide is not routinely used during pregnancy, but a specialist may prescribe it when serious excess fluid requires treatment. It crosses the placenta and may reduce placental blood flow; maternal assessment and additional fetal growth monitoring may be appropriate. Do not stop prescribed treatment without consulting the maternity or specialist team.
furosemide while breastfeeding
Selected product licences contraindicate breastfeeding because furosemide enters breast milk and may suppress milk production. NHS information states that it is not usually used while breastfeeding. The prescriber should assess alternatives and clinical need.
furosemide interactions
This is not a complete interaction list. Check prescribed, over-the-counter and complementary medicines.
NSAIDs, including ibuprofen and indometacin
May reduce the diuretic effect and increase kidney-injury risk, particularly during dehydration or low circulating volume.
Lithium
Furosemide can reduce lithium clearance and cause toxic concentrations, requiring specialist review and monitoring.
Common questions about furosemide
Answers are fully visible for fast scanning and source review.
Can furosemide be taken with food?
Oral furosemide can be taken with or without food. Do not mix oral solution into food or drink unless its specific leaflet says this is suitable.
What if I have vomiting or diarrhoea?
These illnesses increase dehydration and kidney-injury risk. Contact a pharmacist or prescriber and follow any illness plan already provided rather than changing treatment without advice.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.