Furosemide

What it is

Furosemide is a loop diuretic. It blocks salt reabsorption in the loop of Henle in the kidney, so more sodium and water leave the body as urine, which reduces the excess fluid held in the tissues and lungs. It is used for oedema and for fluid overload in heart failure.

Used for

• Oedema
• Heart failure

What to know while taking it

It can be taken with or without food, and is usually taken in the morning because the urine output that follows is heavy and would otherwise disrupt sleep. It flushes out potassium, magnesium, calcium and thiamine along with the water, so potassium, sodium, magnesium, creatinine and uric acid are checked from time to time; enough fluid has to be drunk to avoid drying out. Ibuprofen and diclofenac blunt its effect and strain the kidneys alongside it, and the potassium loss it causes makes digoxin more likely to become toxic.

When to see a doctor

See a doctor for muscle cramps or weakness, an irregular or racing heartbeat, marked dizziness or confusion, very little urine, or any ringing in the ears or change in hearing, which can follow high doses.

Worth knowing

• Can lower potassium
• Drink enough water
• High doses can affect hearing

Markers to watch

• Potassium
• Sodium
• Magnesium
• Creatinine
• Uric acid

Nutrients affected

• potassium — depleted by (Potassium)
• magnesium — depleted by (Glucose, HOMA-IR, Magnesium)
• calcium — depleted by (Calcium, ionized, Calcium, total, Ferritin)
• vitaminB1 — depleted by