Furosemide is a type of medicine called a diuretic. It's used to treat high blood pressure (hypertension), heart failure and a build up of fluid in the body (oedema).
It's also sometimes used to help you pee when your kidneys are not working properly.
Diuretics are sometimes called "water tablets" because they make you pee more. This helps get rid of extra fluid in your body.
Furosemide is only available on prescription. It comes as tablets and a liquid that you swallow. It can also be given by injection, but this is usually only done in hospital.
Furosemide sometimes comes mixed with other diuretics, including with:
- amiloride (called co-amilofruse, Frumil or Frumil LS)
- spironolactone (called Lasilactone)
- triamterene (called Frusene)
Who can take furosemide
Most adults and children (including babies) can take furosemide.
Who may not be able to take furosemide
Furosemide is not suitable for everyone. To make sure it’s safe for you, tell your doctor if you have:
- ever had an allergic reaction to furosemide or any other medicine
- low blood pressure (hypotension)
- signs of dehydration, such as being thirsty, having a dry mouth and dark pee
- liver disease
- any difficulty peeing
- Addison's disease, a rare disorder of the adrenal glands
Tell your doctor that you are taking furosemide if you're going to have:
- a glucose test
- a test (such as an X-ray or scan) that involves using a dye containing iodine being injected into your blood
- a major operation or a general anaesthetic to put you to sleep
Dosage and strength
Furosemide tablets come in 20mg, 40mg and 500mg strengths.
Liquid furosemide comes as 20mg, 40mg or 50mg strengths (in every 5ml).
The usual dose to treat adults with:
- high blood pressure is 40mg to 80mg a day
- heart failure or oedema is 20mg to 120mg a day
Doses are usually lower for people over 65 years as they may be more prone to side effects.
For babies and children, your doctor will use your child's weight or age to work out the right dose.
How to take it
Furosemide does not usually upset your stomach so you can take it with or without food.
Swallow the tablets whole with a drink of water.
If you're taking furosemide as a liquid, it will come with a plastic spoon or syringe to help you measure out the correct dose. If you do not have one, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not measure the right amount.
When to take it
You’ll usually take furosemide once a day in the morning.
Sometimes you’ll take it twice a day – once in the morning and again at lunchtime. Occasionally, you take it every other day.
You do not need to take furosemide at the same time every day. You can occasionally take it at a different time if it's more convenient for you, for example if you need to go out for a few hours in the morning and you will not be near a toilet.
Try not to take furosemide too late in the day (after 4pm) or at night, otherwise you may have to wake up to go to the toilet. Your doctor or pharmacist will suggest the best times for you to take your medicine.
If you get ill while taking it
Contact your doctor if:
- you have a high temperature
- you’re sweating and shaking
- you’re being sick (vomiting) or have severe diarrhoea
Your doctor may recommend you stop taking furosemide for 1 to 2 days until you are better. You can start taking it again when you're eating and drinking normally.
If you take furosemide when you have an illness that makes you dehydrated, it can make the dehydration worse.
How long to take it for
Depending on why you're on furosemide, you may have to take it for a long time, even for the rest of your life.
If you forget to take it
If you forget to take your dose, take it as soon as you remember, unless it is after 4pm. In this case, leave out the missed dose and take your next dose at the usual time.
Do not take 2 doses to make up for a forgotten dose.
If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicines.
If you take too much
Taking too much furosemide can cause headaches, make you feel dizzy, have a pounding or irregular heartbeat and make you faint. You may also pee more than normal and feel thirsty.
The amount of furosemide that can lead to an overdose varies from person to person.
You take more than your prescribed dose of furosemide and:
- feel unwell
- you are over 65 (even if you feel well)
- you have kidney, liver or heart failure (even if you feel well)
Go to 111.nhs.uk or call 111 .
Call 111 if you need advice about a child under the age of 5 years.
If you go to A&E, take the furosemide packet, or the leaflet inside it, plus any remaining medicine with you.
Talk to your doctor if you want to stop taking furosemide.
Stopping it may cause your blood pressure to rise, and this may increase your risk of heart attack and stroke.
If you're bothered by side effects, your doctor may be able to prescribe you a different medicine.
Common side effects
These common side effects of furosemide happen in more than 1 in 100 people. There are things you can do to help cope with them:
Speak to a doctor or pharmacist if any of these side effects bother you or last more than a few days.
Serious side effects
Some people have serious side effects after taking furosemide.
Tell your doctor or contact 111 now if you get:
- unexplained bruising or bleeding, a high temperature, sore throat and mouth ulcers – these could be signs of a blood disorder
- severe stomach pain which could reach through to your back – this could be a sign of an inflamed pancreas (pancreatitis)
- severe pain in your side or blood in your urine – these could be signs of inflamed kidneys
- ringing in your ears (tinnitus) or loss of hearing
Go to 111.nhs.uk or call 111.
Call 111 if you need advice for a child under the age of 5 years.
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to furosemide.
These are not all the side effects of furosemide. For a full list, see the leaflet inside your medicine packet.
Furosemide and pregnancy
Furosemide is safe to take in pregnancy, although it will only be prescribed if you have specific medical conditions.
If you're trying to get pregnant or are already pregnant, talk to your doctor about whether taking furosemide is right for you.
Furosemide and breastfeeding
If your doctor or midwife says your baby is healthy you can take furosemide while you’re breastfeeding.
It is not known how much furosemide gets into breast milk but it’s likely to be a small amount. It would not be expected to cause any side effects in your baby, but furosemide may reduce the amount of milk you produce.
If you’re breastfeeding, or planning to breastfeed, talk to your doctor or pharmacist as other medicines might be better while breastfeeding. It is important that you take the medicine that works for you. If you need to take furosemide while you're breastfeeding, your doctor and midwife will monitor your baby's weight.
If you notice that your baby is not feeding as well as usual or if you have any other concerns about your baby, then talk to your health visitor, midwife, pharmacist or doctor as soon as possible.
Furosemide and fertility
There's no evidence that furosemide reduces fertility in men or women. However, if you're trying to get pregnant, talk to your doctor first as hey will need to review your medical condition and medicine before you try for a baby.
Cautions with other medicines
Some medicines can affect the way furosemide works. They can stop it working properly or increase the chances of you having side effects.
Tell your doctor if you're taking:
- medicines to treat, or which have the side effect of, an irregular heartbeat, including amiodarone, digoxin, disopyramide, flecainide or sotalol
- medicines that can change the level of potassium in your blood, such as potassium supplements, steroids, or other diuretics
- medicines used to treat mental health problems, such as amisulpride, lithium, pimozide or risperidone
- painkillers known as non-steroidal anti-inflammatory drugs (NSAIDs), including diclofenac, ibuprofen or naproxen
- medicines that treat high blood pressure, or those that have a side effect of low blood pressure
- a medicine used to treat ulcers called sucralfate – leave about 2 hours between the time you take furosemide and sucralfate
Taking furosemide with painkillers and remedies
Some painkillers and remedies contain a lot of sodium, which is found in salt. Too much salt can stop furosemide working properly.
Medicines that contain a lot of salt include:
- soluble paracetamol
- soluble co-codamol
- some remedies for heartburn and indigestion
Speak to a pharmacist or doctor to see if these medicines are safe for you to take alongside furosemide.
Mixing furosemide with herbal remedies and supplements
Tell your doctor if you are taking any potassium supplements. These change the levels of potassium in your blood and can affect the way furosemide works.
There's not enough information to say that other herbal remedies or supplements are safe to take with furosemide. They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.
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