Loop diuretic
Furosemide drug interactions: a practical overview
Drug interactions are the single biggest cause of preventable medication problems. Furosemide (Furosemide) interacts to varying degrees with several classes of medication and with a smaller list of foods. This page summarises the practically important ones at 20mg, 40mg, 100mg, framed for a real-world prescription review rather than an exhaustive PDF list.
High-priority interactions for Furosemide
For Furosemide, the most clinically relevant interactions are typically with strong CYP3A4 inhibitors and inducers, with cardiovascular medications (notably nitrates for several Loop diuretic agents), with central nervous system depressants, and with medications affecting blood pressure or heart rate. Furosemide acts on the thick ascending limb of the loop of Henle in the kidney, where it inhibits the Na+/K+/2Cl- co-transporter (NKCC2).
Working with the pharmacist
A pharmacist review of all current medications is the practical safeguard against unintended interactions with Furosemide. According to the prescribing information for Furosemide, the full medication list — prescription, OTC, supplements and recreational substances — should be reviewed before starting and at every dose change at 20mg, 40mg, 100mg.
Frequently asked questions
What's the most important Furosemide interaction to know? ▾
For most Loop diuretic medications, the highest-priority interaction is with nitrate medications used for chest pain — this combination is often a hard contraindication. After that, strong CYP3A4 inhibitors (some antifungals, macrolides) are the next concern at routine 20mg, 40mg, 100mg doses.
Do I need to tell the pharmacist about supplements? ▾
Yes. Supplements and herbal products can interact with Furosemide in ways that prescription drug-drug interaction databases miss. The pharmacist needs the complete picture — including supplements like St John's Wort, grapefruit-containing products and high-dose vitamins — to flag risks at 20mg, 40mg, 100mg.
Products containing Furosemide
More on Furosemide
- With alcoholFurosemide and alcohol — is it safe to drink?
- With foodShould Furosemide be taken with food?
- Side effectsFurosemide side effects: common, rare and warning signs
- Dosage guideFurosemide dosage guide: how much to take and when
- OnsetHow fast does Furosemide start working?
- DurationHow long does Furosemide last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.