A quick look at the facts

Bioactive ingredient
Furosemide (also spelled frusemide in older UK sources)
Drug class
Loop diuretic
Typical strengths in the UK
Commonly 40 mg and 100 mg tablets; other forms exist for specialist use
Frequent clinical uses
Relief of fluid retention from heart, liver or kidney disease, acute pulmonary oedema, and adjunct in some hypertensive situations
Related topics
Blood pressure control, diuretic selection, and anti-doping considerations

If you are unfamiliar with this medicine, begin with the Overview page. For safety issues read Safeguards and verify the details Medication Interaction Effects. For information on legal issues jump to Legislative and Regulatory affairs Notices.

Panorama of the crestic: what furosemide does and how the workflow comes together

Furosemide (brand name Lasix) produces a strong diuretic effect by blocking the reabsorption of sodium and chloride in the thick ascending limb of the loop of Henle in the kidney. The result is increased urine output and loss of several electrolytes including sodium, chloride, potassium, calcium and magnesium.

It is widely used to reduce oedema associated with heart failure, liver cirrhosis and renal disease. In emergency care it helps manage acute pulmonary oedema, and in some specialist settings it is used to assist with blood pressure control or cerebral oedema under expert supervision.

To jump straight to unfavorable health effects, go to Possible drug adverse outcomes, or to risk alerts on user two-way communication in action see Drug Interaction Issues.

Instructions for dosage and administration

Always follow the exact instructions given by your prescriber. Take the tablets using water to aid swallowing. Taking doses earlier in the day helps avoid nocturnal urination that can disturb sleep.

See Dose was not taken for guidance on a forgotten tablet. If you have concerning symptomsreconsideration Overdose and Potential medication undesired reactions.

Important safety measures before treatment and during treatment

Tell your doctor or pharmacist about all medical conditions and medicines you take. Extra caution is needed in the presence of:

Furosemide increases the chance of dehydration and electrolyte imbalance. Your clinician may recommend blood tests and will advise on fluid intake. The drug can cause dizziness; do not drive or operate machinery until you know how it affects you. Pregnant or breastfeeding patients should only use it after discussion with their clinician.

Conditions under which furosemide should be avoided

Furosemide should be avoided unless a specialist decides otherwise in these situations:

Potential effects during use

Contact a healthcare professional immediately if you notice signs of an allergic reaction such as rash, wheeze or facial swelling.

Other symptoms that need prompt attention include:

Because furosemide can cause electrolyte disturbances such as low potassium, sodium or magnesium, your team may do periodic blood tests to monitor levels and adjust treatment.

Drug communication in action guidance to keep in mind

Certain drug combinations increase risks or reduce the effect of medicines. Important examples include:

Always show your current medication list to any prescriber. If you develop symptoms listed in Possible therapy post use effects, seek urgent advice.

Steps to take for a the dose was missed

If you miss a single tablet:

Hospital or single-dose administrations follow the schedule set by clinical staff; speak to them if you have concerns.

Overdose syndrome

Seek immediate medical help or call emergency services if someone has taken too much furosemide or shows severe symptoms such as fainting, extreme weakness, confusion, persistent dizziness, severe thirst or hearing problems. In an intentional overdose can lead to severe dehydration, electrolyte imbalances, hypotension and auditory effects.

Storage unit

Substitute therapies and comparable drugs

Selection of an the other option depends on the clinical situation, kidney function and treatment goals. Options often considered include:

Discuss tolerability, real time monitoring needs and costs with your clinician or pharmacist. See Prices around the United Kingdom to lay out a rough cost comparison.

Price dynamics in the UK - rough guide in GBP

Prices vary by NHS prescriptions, private supply, brand, and pack size. The figures here are approximate and intended for general orientation only.

Ask your pharmacist whether a generic substitute or a larger pack will reduce your per-tablet cost.