Lasix 40: Uses, How It Works, Side Effects
Also in: हिन्दी தமிழ் मराठी తెలుగు ಕನ್ನಡ বাংলা ગુજરાતી മലയാളം ਪੰਜਾਬੀ
Also known as: Lasix, Lasix 40 mg, Lasix 40 tablet, Furosemide 40 mg, Frusemide 40 mg
Lasix 40 is a prescription tablet containing 40 mg of furosemide, a 'water tablet' (loop diuretic) used to remove extra fluid from the body. It is used for swelling caused by heart failure, kidney disease or severe liver disease, and sometimes for high blood pressure. It makes you pass more urine. It is taken only on a doctor's prescription, and dehydration and low salt levels need watching.
- Active ingredient
- Furosemide 40 mg
- Type of medicine
- Loop diuretics
- Used for
- Heart failure, High blood pressure
- Starts working in
- You usually start passing more urine within an hour or so of a dose
- Effect lasts
- The extra urine passing lasts for some hours; it is often taken in the morning
- With or without food
- Can be taken with or without food; follow the label or your doctor's advice
- Alcohol
- Best avoided, as it can add to dizziness and dehydration
- Pregnancy
- Not usually used in pregnancy; tell your doctor if you are or may be pregnant
- Habit-forming
- No
- Made by
- Sanofi India Ltd
Pharmacist review in progress. This page is based on the sources listed below and is being checked by our registered pharmacist.
On this page
What is Lasix 40 used for?
Lasix 40 is a prescription medicine. It is used, on a doctor's advice, to remove extra fluid from the body.
- Treating swelling (oedema) caused by heart failure, chronic kidney disease or severe liver disease (cirrhosis)
- Sometimes, treating high blood pressure, when a doctor prescribes it for this
How does Lasix 40 work?
The kidneys filter the blood and normally take back most of the salt and water. Furosemide acts on a part of the kidney tubule called the loop of Henle and stops salt being taken back, so more salt and water leave in the urine. This reduces extra fluid in the body, easing swelling and breathlessness, and can lower blood pressure.
What happens in your body after you take it
You swallow the tablet
The tablet dissolves in the gut and furosemide is absorbed into the blood. It can be taken with or without food.
It travels to the kidneys
Furosemide is carried in the blood to the kidneys, where it reaches the inside of the kidney tubules.
It blocks salt reabsorption
In the loop of Henle, furosemide stops salt from being taken back into the body, and water follows the salt.
You pass more urine
More salt and water leave in the urine, and the extra fluid in the body falls. Swelling and breathlessness from fluid can ease.
The effect wears off
The extra urine passing lasts for some hours and then settles, which is why many people take it in the morning. Blood tests check salts and kidney function.
How to take Lasix 40
Take Lasix 40 exactly as your doctor has prescribed or as printed on the pack. Your doctor decides the dose, the time of day and how long you need it.
- It is often taken once a day in the morning at first, so that passing urine does not disturb sleep. Follow your doctor's advice.
- It can be taken with or without food. Follow the label or your doctor's advice.
- If you miss a dose, take it when you remember, unless the next dose is nearly due. Do not take two doses together.
- Do not stop taking it on your own; talk to your doctor first.
- Your doctor may ask for regular blood tests to check salts and kidney function, especially for long-term use.
Side effects of Lasix 40
Most people take furosemide without serious problems. Some side effects are common and mild, but a few need medical help.
Uncommon or mild
- Needing to pass urine more often
- Thirst
- Dizziness
- Headache
- Muscle twitches or cramps
Rare but serious: get medical help
- Signs of dehydration: dry mouth, strong thirst, dark urine, passing little urine, dizziness, tiredness or confusion
- Swelling of the face, lips, tongue or throat, or difficulty breathing (a severe allergic reaction). Get medical help immediately
- Blistering skin with flu-like symptoms (a rare severe skin reaction). Get medical help immediately
- Passing much less urine, or other signs of kidney problems
Who should be careful
Some people need to check with a doctor before taking Lasix 40, or need extra care while taking it.
When the label says not to use it
- Allergy to furosemide or any ingredient of the tablet
- Being unable to pass urine
- Severe dehydration or very low blood salts
- Kidney or liver problems
- Diabetes, gout or Addison's disease
- Low blood pressure
- A past allergic reaction to furosemide, another diuretic or a sulfonamide-type medicine
- Pregnancy and breastfeeding: it is not usually used; talk to your doctor
- Vomiting, diarrhoea or fever: you can become dehydrated; ask your doctor what to do about the tablets
- Dizziness: take care when standing up and when driving
Medicines and things that interact with Lasix 40
Lasix 40 can change how other medicines work, and some medicines change its effect. Tell your doctor or pharmacist about everything you take, including herbal remedies and painkillers bought over the counter.
- Other blood pressure medicines, including ACE inhibitors and beta blockers: blood pressure may fall too low
- Digoxin and some heart rhythm medicines: low potassium can make them riskier
- Potassium-raising medicines or supplements, and lithium
- NSAID painkillers such as ibuprofen: they can weaken the effect and strain the kidneys
- Laxatives: more risk of losing potassium
- Some antidepressants, fluconazole and risperidone
- Alcohol: can add to dizziness and dehydration
If someone takes too much
Taking more than prescribed can be dangerous, causing heavy fluid loss, dizziness and fainting. If someone has taken more than prescribed, call 112 or go to the nearest hospital and take the medicine pack with you.
Storage
Store below 30 C in a dry place, protected from light and moisture, in the original strip, and out of the reach of children. Do not use after the expiry date. Check the pack for the exact storage instructions.
Regulatory status in India
Approved for sale in India as a prescription medicine. Single-ingredient furosemide is not on the CDSCO list of medicines banned under section 26A of the Drugs and Cosmetics Act. Lasix 40 contains furosemide only.
Other brands with the same medicine
Furosemide 40 mg tablets are sold under other brand names and as generic medicines. They contain the same medicine; check the label for the strength. Some products also contain other medicines, so do not switch between them without asking your doctor.
Other strengths and forms
Furosemide is also sold as 20 mg tablets, as liquid and as injections, and in combination tablets with other medicines. The strength and contents are printed on the pack and are not the same across products, so check the label of the one you have.
Common questions
Is Lasix 40 a prescription medicine?
Yes. Furosemide is a prescription-only medicine. It should be taken only if a doctor has prescribed it, and it should not be started, stopped or changed without the doctor's advice.
Why does Lasix 40 make me pass so much urine?
It stops the kidneys taking back salt, so salt and water leave in the urine. This removes extra fluid from the body. Ask your doctor about the best time of day to take it; many people take it in the morning.
What should I do if I am sick or have diarrhoea on Lasix 40?
Vomiting, diarrhoea or fever can lead to dehydration, and the tablets can make it worse. Signs include dry mouth, thirst, dark urine, dizziness and confusion. Contact your doctor or pharmacist for advice; do not decide yourself.
What should I do if I miss a dose of Lasix 40?
Take it when you remember, unless your next dose is nearly due. Then skip the missed dose. Never take two doses together to make up for a missed one.
Can I drink alcohol while taking Lasix 40?
It is best avoided, because alcohol can add to dizziness, light-headedness and dehydration. Ask your doctor what is reasonable for you.
Do I need blood tests on Lasix 40?
Yes, often. Furosemide can change the levels of salts such as potassium and sodium and affect the kidneys, so doctors check blood tests from time to time, especially with long-term use. Follow your doctor's advice.
Is Lasix 40 safe in pregnancy?
It is not usually used in pregnancy or breastfeeding. If you are pregnant, may become pregnant or are planning a baby, tell your doctor. Do not stop a prescribed medicine without speaking to your doctor first.
What is the difference between Lasix 40 and furosemide 40 mg?
Lasix is a brand name, and furosemide is the medicine inside it. Generic furosemide 40 mg tablets contain the same active ingredient. Check the strength and ingredient list on the pack, and ask your doctor before switching.
Sources
- Furosemide: a medicine to remove excess fluid. NHS (UK)
- Heart failure. NHS (UK)
- ATC/DDD Index: C03CA01 furosemide. WHO Collaborating Centre for Drug Statistics Methodology
- List of drugs prohibited for manufacture and sale through gazette notifications under section 26A of the Drugs & Cosmetics Act 1940. Central Drugs Standard Control Organisation (CDSCO)