Furosemide, sold as Lasix, is a loop diuretic — a strong "water pill" — used to remove excess fluid in heart failure, kidney or liver disease, and sometimes high blood pressure. By making the kidneys pass more salt and water, it also lowers potassium and other electrolytes, which is the source of most of its interactions. Knowing the main furosemide interactions and side effects helps you take it safely.
Key takeaways about furosemide
- Furosemide (Lasix) is a loop diuretic that removes excess fluid.
- It can lower potassium, sodium, and magnesium.
- Regular NSAIDs can reduce its effect and strain the kidneys.
- Low potassium can make some heart medicines, such as digoxin, riskier.
- Report cramps, an irregular heartbeat, severe dizziness, or hearing changes.
Furosemide interactions to review
Several combinations deserve a closer look. Other blood pressure medicines can add to furosemide's effect and drop pressure too far. Regular NSAIDs such as ibuprofen or naproxen can blunt its action and, together, stress the kidneys. Because furosemide lowers potassium, it can make digoxin more likely to cause heart-rhythm problems, and it needs care alongside other medicines affected by electrolytes or by the kidneys. The exact effect depends on your full list and doses, so ask a pharmacist to review it.
Side effects and warning signs
- Frequent urination, dehydration, thirst, or dizziness — especially when standing.
- Muscle cramps or weakness, which can signal low potassium.
- A fast or irregular heartbeat — report promptly.
- Rarely, hearing changes or ringing in the ears, especially at high doses.
This is not a complete list. Taking furosemide early in the day usually prevents nighttime bathroom trips, and your prescriber will tell you whether you need extra potassium.
How MedSafeScan helps
MedSafeScan lets you keep furosemide alongside your other heart and blood pressure medicines, OTC pain relievers, and any potassium supplement, so overlaps and electrolyte-related risks are easier to spot and raise with a pharmacist. Treat any interaction result as a starting point for a professional conversation, not a final decision.
MedSafeScan provides informational guidance only and is not a substitute for professional medical advice. Always consult your healthcare provider before making any changes to your medications.
Quick answers
What should you not take with furosemide?
Be cautious combining furosemide with other blood pressure medicines (the effects can add up), regular NSAIDs such as ibuprofen (which can reduce furosemide's effect and strain the kidneys), and certain other drugs affected by low potassium, such as digoxin. Tell your prescriber about all medicines and supplements so the pair can be checked.
Does furosemide lower potassium?
Yes. Furosemide is a loop diuretic that can lower potassium and other electrolytes such as sodium and magnesium. Low potassium can cause muscle cramps, weakness, or an irregular heartbeat, and it raises the risk of problems with some heart medicines. Your prescriber may check blood tests and sometimes recommend a potassium supplement.
What are the common side effects of furosemide?
Because it increases urination, common effects include needing to urinate more, dehydration, dizziness, and low electrolytes. Report muscle cramps, a fast or irregular heartbeat, severe dizziness, or hearing changes. Taking the dose earlier in the day helps avoid nighttime trips to the bathroom. Read your product's patient information for the full list.
Sources and further reading
These public resources are provided for background reading. They do not replace advice from your pharmacist, doctor, or other licensed healthcare professional.
Last reviewed: October 4, 2026