Furosemide is a type of medicine called a diuretic. Diuretics are commonly known as ‘water tablets’ as they are used to treat a condition where your body is retaining too much water. They get rid of excess water from your kidneys by making you pee. Furosemide is also sold under the brand names Frusol and Lasix. Furosemide sometimes comes mixed with other diuretics or potassium. Furosemide tablets contain 20g of the active ingredient, Furosemide. They also contain lactose, magnesium stearate, maize starch, stearic acid.

Uncomfortable, swollen legs, feet or ankles? You could be suffering from Oedema.Oedema is when your body is retaining too much fluid. It has many different causes, from excess weight or excess salt consumption to more serious issues like kidney or liver problems. Fluid retention causes swelling around the feet, ankles and legs. These areas can become puffy and uncomfortable, feel heavy and swollen. The skin can feel tight and sore. Oedema will often go away on its own, but if the condition does not ease within a few days you should seek medical help. Obvious symptoms of oedema are:

  • Swollen, puffy feet, ankles or legs
  • Shiny, red stretched skin over the swollen areas

To help alleviate these symptoms, you can try light exercise if possible or try raising your feet on a footstool or pillow when you are sitting down. It is also worth making sure that your clothing and shoes are loose and comfortable. Remember to keep your feet and legs clean, dry and well moisturised to avoid infection. Medication like Furosemide may be prescribed if you are suffering from fluid retention and the symptoms do not simply go away on their own after a few days.

What is Furosemide?

Furosemide is a type of medicine called a diuretic. Diuretics are commonly known as ‘water tablets’ as they are used to treat a condition where your body is retaining too much water. They get rid of excess water from your kidneys by making you pee. Furosemide is also sold under the brand names Frusol and Lasix. Furosemide sometimes comes mixed with other diuretics or potassium. Furosemide tablets contain 20g of the active ingredient, Furosemide. They also contain lactose, magnesium stearate, maize starch, stearic acid.

When is Furosemide used?

Furosemide is used to treat fluid accumulation. It can be used in some different situations that result in edema – swelling of the legs, feet and ankles. The swelling means that your body is holding too much water. If the swelling and water retention does not solve itself within a few days, you can be prescribed Furosemide to help. Furosemide assists your kidneys in getting rid of excess water by making you pee. Common causes of edema or fluid retention are:

  • Problems with your kidneys, heart or liver. Therefore your doctor can prescribe Furosemide
  • Excess weight
  • Pregnancy
  • Excess salt
  • Certain medication (blood pressure medication, contraceptives etc.)
  • Infection
  • Blood clots, deep venous thrombosis
  • A sprain or strain injury
  • An insect bite or sting

Furosemide can also be prescribed to treat high blood pressure and heart failure and problems with your blood vessels as these often result in edema.

How do you use Furosemide?

Furosemide is a prescription only medication. It comes as a tablet, liquid or injection. The injection is usually only given in hospital. If you are taking Furosemide at home it will come in tablet or liquid form. Tablet form is the most common. The tablets each contain 20mg of the active ingredient Furosemide. They are uncoated white tablets. If you are using the liquid medicine please ensure you have a proper medicine spoon or syringe to get the dosage right (see below for more information on dosage). Furosemide is usually taken in the morning as it makes you pee frequently. This causes less of a disturbance to your usual daily routine when taken earlier in the day.

What dosages are there?

Always follow the instructions given to you by your doctor. Tablets should be swallowed with a glass of water. Each Furosemide tablet contains 20g of Furosemide.

  • Adults and children over 12 years For water retention: usually 40mg in the morning then 20mg per day or 40mg every other day. You may be prescribed up to 80mg per day
  • For high blood pressure: 20-40mg twice a day
  • Children under 12: 1-3mg per kg of body weight. Your doctor will work out the precise dosage based on your child’s height and weight. The liquid is often prescribed instead of tablets for children so that the dosage can be administered as precisely as possible
  • Over 65 years old: doses may be reduced for people over 65 as they are more prone to side effects. The maximum daily dose is usually 120mg.

It is usual to take Furosemide in the morning as you will need to pee within around 30 minutes and again a few hours later. You may need to pee frequently for up to six hours. You should not take Furosemide after 4 pm as you are likely to need to wake up in the night to use the toilet. You should also monitor your water intake when taking Furosemide to avoid becoming dehydrated whilst ensuring you don’t drink too much for the medication to be effective.Furosemide doesn’t need to be taken at the same time every day. You can alter the timings to fit with your daily schedule. If you know you are going to be out an about with little access to a toilet one morning then you could put off taking your tablet until you come home. Don’t forget to take it before 4pm though to avoid interrupting your sleep to go to the toilet. If you forget to take Furosemide in the morning you can simply take it later in the day, but if it’s after 4 pm it’s better to miss your medication for that day. Do not take a double dose to make up for a forgotten dose.

What are the side effects of Furosemide?

As with all medications, there are possible side effects when you take Furosemide. Not everybody suffers from side effects. You should seek medical help if you are concerned. Common side effects that affect 1 in 10 people taking Furosemide are:

  • Dehydration
  • Chemical imbalance leading to dry mouth, weakness, drowsiness, tiredness, restlessness, muscle pain, fits, fatigue or cramps
  • Low blood pressure causing: loss of concentration, slowed reaction time, difficulty passing water, fast or irregular heart rate, nausea, sickness
  • Low blood volume (hypovolemia)
  • Increased creatinine and blood urea

There are several things you can do to help alleviate the most common side effects.

  • Dry mouth: Chew sugar-free gum or suck sugar-free sweets.
  • Headache: Rest and drink plenty of fluids. Check with your doctor how much you should be drinking while taking this medication.
  • Frequent urination: It isn’t something you should worry about, but if this is a problem for you try timing your medication to make life easier. You will need to pee frequently for about 6 hours after you take the tablet. We do not recommend you take the tablet after 4 pm.
  • Thirsty: Check with your doctor how much you can drink while taking Furosemide. It will depend upon the reason for the prescription. You should not allow yourself to become dehydrated.
  • Confusion or dizziness: Take your time standing up when you have been sitting or lying down. If you are feeling dizzy remain seated or lying down until it passes. Do not attempt to drive or operate heavy machinery if you have this side effect.
  • Nausea or vomiting: Take your medication with a small snack. Sip water regularly to avoid becoming dehydrated. Avoid rich or spicy foods. This side effect usually only lasts a few days. If these symptoms persist consider talking to your doctor about anti-nausea medication.

Less common side effects, affecting 1 in 100 people:

  • Anaemia
  • Changes in body levels of glucose, cholesterol and uric acid (shown in tests)
  • Gout
  • Changes in vision, including yellow or blurred vision
  • Feeling light-headed or dizzy
  • Feeling pressure around the head
  • Irregular heartbeat
  • Changes in bowel movements including diarrhoea and constipation
  • Deafness (sometimes irreversible)

Some people experience serious side effects when taking Furosemide. If you experience any of the following serious side effects, you should contact your doctor straight away.

  • Severe pain in your side or blood in your urine: these could be signs of a kidney problem
  • Unexplained bruising or bleeding, fever, sore throat and mouth ulcers: these could be signs of a blood problem
  • Severe tummy pain passing through to your back: this could be a sign of a problem with your pancreas
  • Ringing in your ears or loss of hearing

It is also possible to have a serious allergic reaction to Furosemide. If you think you are having an allergic reaction contact emergency services straight away. Signs of a serious allergic reaction include:

  • Wheezing
  • A red itchy, swollen or blistered skin rash
  • Difficulty breathing or talking
  • A tight feeling in your chest or throat
  • Swelling around your face, mouth, throat or tongue

When shouldn’t you use Furosemide?

You should not take Furosemide if you are allergic to any of the ingredients. Do not drive or operate machinery if you are taking Furosemide and you feel more tired than usual. Consult your doctor if you are pregnant, breastfeeding or planning a pregnancy. It is not generally recommended to take Furosemide when pregnant or breastfeeding, but your doctor may consider that the benefits outweigh the risks. Do not drink alcohol when taking Furosemide as this may lower the blood pressure to dangerous levels.

Do not take Furosemide if you suffer from any of the following:

  • Low blood pressure
  • Low levels of protein in the blood
  • Kidney problems
  • Liver problems
  • Diabetes
  • Prostrate trouble
  • Gout
  • An abnormal blood condition

You should also avoid taking Furosemide if you are dehydrated, have low levels of potassium, sodium or other electrolytes in your blood, have digitalis poisoning or Addison’s disease. You should always discuss any other medication you are taking, including herbal supplements, with your doctor.

Does Furosemide interact with other medication?

Please tell your doctor what other medication you are taking as Furosemide may react with certain medication. Some medication will make Furosemide less effective, while other medication may increase the risk of unpleasant side effects or make these worse.

Medication that is generally not recommended when taking Furosemide includes:

  • Anything which treats, or has the side effect of an irregular heartbeat
  • Non-steroid anti-inflammatory drugs (NSAIDS): this are painkillers like ibuprofen or diclofenac.
  • Medicines which affect the potassium level of your blood
  • Medicines to treat high blood pressure (or anything that lowers blood pressure)
  • Medicines used to treat mental health issues, e.g. antidepressants.
  • Sucralfate: a medicine used to treat ulcers. You should leave at least 2 hours between taking Furosemide and taking Sucralfate
  • Over the counter remedies that contain a lot of sodium (salt) for example soluble paracetamol or heartburn and indigestion cures


  • Aspirin
  • Antibiotics
  • Medication for ADHD
  • Cancer treatments
  • Laxatives
  • Oral contraceptives
  • Muscle relaxants
  • Certain medication for asthma

Where can you buy Furosemide?

Furosemide is only available from a pharmacist.

Can I get Furosemide without a prescription?

Furosemide is a prescription only medicine, you must have a prescription from your doctor to buy it from a pharmacy.


Actavis, Furosemide tablet 20mg (June 2017) Retrieved from

NHS UK, Furosemide (2019, January 10th) Retrieved from

Patient Leaflet(s)
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