Furosemide for ascites
Content date: 15 November 2026
Furosemide, also sold as Lasix, helps the kidneys remove excess salt and water. It may be added to spironolactone for ascites and leg swelling. Dosing depends on kidney function, blood salts and response.
Your next step
Check your written prescription and monitoring plan. If anything is unclear, ask your care team before changing a dose.
Get urgent help: Seek emergency care for fainting, new confusion, palpitations with severe weakness, severe breathlessness, or sudden tongue or throat swelling. Fever or new abdominal pain in someone with ascites needs urgent assessment; do not wait for both.
How do I use it?
- Take it as prescribed, usually in the morning. If a second dose is prescribed, it is generally taken earlier in the day to reduce night-time urination. Follow your product instructions about food. Measure liquid medicine with the supplied device, not a kitchen spoon.
- Take a missed dose when remembered unless the next is nearly due; then skip it without doubling. Ask your pharmacist if you remember late in the evening. Do not add a dose yourself for swelling or weight gain.
How do I store it?
- Keep it in its supplied packaging, away from children, heat and moisture. Follow labelled temperature and light-protection instructions. Ask your pharmacist about expiry after opening a liquid product.
What tests do I need?
- Blood pressure, weight, kidney function, sodium and potassium are monitored; magnesium may also be checked. Tests are repeated after starting or changing treatment, sooner if risk is higher. Record morning weight consistently, after passing urine and before breakfast, and share the record. Losing weight as quickly as possible is not the goal.
Possible side effects: what to expect
- Passing more urine is expected; dizziness on standing, thirst or muscle cramps can occur. Rise slowly and keep to your prescribed fluid plan rather than drinking extra water automatically.
- Excess fluid loss can lower sodium or potassium and worsen kidney function. Weight, blood-pressure and blood-test checks help guide safe dosing. Report persistent cramps or dizziness; reduced urine or ongoing vomiting/diarrhoea needs same-day advice. Hearing changes also need prompt review.
Important points
- Do not automatically take potassium supplements, especially with spironolactone; blood tests determine whether you need them.
- Have all medicines checked, especially ibuprofen, diclofenac, lithium and blood-pressure drugs. Do not stop prescribed medicines yourself. Follow your salt and fluid plan; ascites does not mean everyone needs fluid restriction, or that increased urination requires drinking large amounts.
Brand: ........................ | Dose and how I take or use the medicine: ........................
Next dose: ........................ | Next blood tests: ........................
Team contact: ........................
When to get help
Seek emergency care for fainting, new confusion, palpitations with severe weakness, severe breathlessness, or sudden tongue or throat swelling. Fever or new abdominal pain in someone with ascites needs urgent assessment; do not wait for both.
Contact your team the same day for reduced urine, persistent vomiting or diarrhoea, worsening dizziness, rapid weight loss, or hearing changes. The team may adjust or temporarily withhold treatment.