Furosemide is a 'water tablet' (a diuretic).
It is best taken in the morning.
Any side-effects are usually mild, but can include feeling sick (nausea) or dizzy.
|Type of medicine||A loop diuretic|
|Used for||Water retention (oedema); high blood pressure (hypertension)|
|Also called||Frumil® (contains furosemide in combination with amiloride; this combination is also called co-amilofruse); Frusene® (contains furosemide in combination with triamterene); Lasilactone® (contains furosemide in combination with spironolactone)|
|Available as||Tablets and oral liquid medicine|
Furosemide belongs to a group of medicines called loop diuretics. A diuretic is a medicine which increases the amount of urine that you pass out from your kidneys. They are often referred to as 'water tablets'. Furosemide is used to clear excess fluid from your body in conditions where your body retains more than it needs. This extra fluid causes you to feel breathless and tired, and your feet and ankles to swell - it is called water retention (oedema), and it is commonly caused by heart failure.
Diuretics are also a common treatment for high blood pressure (hypertension). Furosemide is prescribed for high blood pressure when it cannot be sufficiently controlled by other diuretics. Furosemide can be used on its own as a diuretic, or it can be prescribed as a combination tablet alongside other diuretics such as triamterene, amiloride or spironolactone.
Before taking furosemide
Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking furosemide it is important that your doctor knows:
- If you are pregnant or breastfeeding.
- If you have any difficulties passing urine, or if you have prostate problems.
- If you have gout or sugar diabetes. These conditions can be made worse by diuretics.
- If you have been told you have very low sodium or potassium levels in your blood.
- If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
- If you have ever had an allergic reaction to a medicine.
How to take furosemide
- Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about furosemide and it will also provide you with a full list of the side-effects which you could experience from taking it.
- Take furosemide exactly as your doctor tells you to. It is usual to be prescribed one dose to take each day, and you will be asked to take it preferably in the morning. Some people could be asked to take two doses a day, in which case one dose should be taken in the morning and the other early-mid afternoon. Your doctor will tell you how many tablets (or how much liquid medicine) to take for each dose. You will find the directions for taking the doses printed on the label of the pack, to remind you about what the doctor said to you.
- Although furosemide is preferably taken in the morning, you can take it at a time to suit your schedule. For example, if you want to go out in the morning and don't want to have to find a toilet, you can delay taking your dose until later. However, it is best if you take it no later than mid-afternoon. This is because you will find you need to go to the toilet a couple of times within a few hours of taking it and this will disturb your sleep if you take it too late in the day.
- Swallow the tablet with a drink of water. You can take furosemide either with or without food.
- If you forget to take a dose, take it as soon as you remember. However, if it is after 4 pm in the afternoon, you should leave out the forgotten dose and continue as usual the next day. Do not take two doses together to make up for a missed dose.
Getting the most from your treatment
- Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress. The balance of salts in your blood may be upset by furosemide. Your doctor may want you to have a blood test from time to time to check for this.
- Diuretics like furosemide help you to lose water. Occasionally you may lose too much and become lacking in fluid in the body (dehydrated). Let your doctor know if you feel constantly thirsty and tired, your mouth is dry, you have muscle cramps, or your skin looks and feels dry.
- If you have been prescribed furosemide for high blood pressure, your treatment is likely to be long-term. Although many people with high blood pressure do not feel unwell, if left untreated, high blood pressure can harm your heart and damage your blood vessels. This damage may later result in a heart attack, stroke, or kidney problems, so it is important that you continue to take furosemide regularly to help reduce the risk of this. You may also be given some lifestyle or dietary advice by your doctor, such as stopping smoking, reducing the amount of salt in your diet and taking some regular exercise. Following this advice will also help to reduce the risk of damage to your heart and blood vessels.
- Drinking alcohol while you are on furosemide could make you feel dizzy. Ask for your doctor's advice about whether you should avoid alcohol.
- If you buy any medicines 'over the counter', check with a pharmacist that they are safe to take with your prescribed medicines.
- If you have diabetes, furosemide could affect your blood sugar levels. Test your blood sugar regularly and speak with your doctor if you notice any significant changes.
- If you are due to have an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.
Can furosemide cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the more common ones associated with furosemide. The best place to find a full list of the side-effects which can be associated with your medicine, is from the manufacturer's printed information leaflet supplied with the medicine. Alternatively, you can find an example of a manufacturer's information leaflet in the reference section below. Speak with your doctor or pharmacist if any of the following continue or become troublesome.
|Furosemide side-effects||What can I do if I experience this?|
|Feeling sick (nausea), stomach upset||This is usually mild, but it may help to take furosemide after food|
|Feeling dizzy, particularly when you stand up (due to low blood pressure)||Getting up and moving more slowly should help. Do not drive and do not use tools or machines while affected|
|Dry mouth||Try chewing sugar-free gum or sucking sugar-free sweets|
|Blurred vision, headache, feeling tired||If any of these become troublesome, speak with your doctor|
|Changes to the levels of minerals in your body||Your doctor will ask you to have blood tests to check for this|
If you experience any other symptoms which you think may be due to the medicine, speak with your doctor or pharmacist for further advice.
How to store furosemide
- Keep all medicines out of the reach and sight of children.
- Store in a cool, dry place, away from direct heat and light.
Important information about all medicines
Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine, ask your pharmacist.
Further reading and references
Manufacturer's PIL, Furosemide 40 mg Tablets; Accord-UK Ltd, The electronic Medicines Compendium. Dated February 2016.
British National Formulary, 78th Edition (Sep 2019); British Medical Association and Royal Pharmaceutical Society of Great Britain, London.