A B C D E F G H I J K L M N O P R S T U V W

DIURETICS

What are the types of Diuretics ?

Many are so-called "...thiazides"; like bendrofluazide or hydrochlorothiazide. They have other (brand) names as well. Indapamide, frusemide (Lasix), bumetanide (Burinex) and metolazone are other types. Some diuretics like amiloride (Midamor) and spironolactone (Aldactone) work differently. Diuretics are often combined with one another or with potassium; this may be for convenience or for other reasons dealt with later in this leaflet.

What are Diuretics for ?

Diuretics are used to treat several different conditions where a build-up of fluid in some part of the body is causing a problem. Fluid tends to collect around the ankles in heart, kidney and liver disorders. In addition, heart failure causes fluid to build up in the lungs. Liver problems cause the abdomen to swell with fluid (this is called ascites). Diuretics are also used to treat high blood pressure (hypertension), glaucoma (a build-up of fluid in the eye), premenstrual symptoms and in Meniere's disease (a build-up of fluid in the inner ear).

How do Diuretics work ?

Diuretics all act on the kidneys, causing them to get rid of more salt (sodium) and water. This increases the amount of urine and takes any unwanted fluid out of your body tissues. This reduces any swelling (oedema) that this fluid may be causing. By reducing the body's water content and other actions, blood pressure is lowered as well.

How should Diuretics be used ?

Because they mostly work quite quickly, they need to be taken in the morning. In this way, you can get rid of your extra water during waking hours. They mostly need to be taken on a regular daily basis, although doctors sometimes advise treatment every other day, or weekdays only. They should not be taken just when you feel like it, although some women find that a few days' course leading up to the period often works well in premenstrual fluid retention.

During Treatment with Diuretics

The most obvious effect of treatment is to make you pass more urine and more often. This happens particularly at the start of treatment. The swelling and any breathlessness should reduce. You may lose anything up to 1 to 2 kg (2 to 4 lb) a day to begin with. You should feel much the better for it. If your treatment is for high blood pressure you may not notice any change in your wellbeing, but your doctor will check that your blood pressure is falling to safer levels. You may notice that you feel more thirsty. Slight or occasional thirst often occurs, but if it lasts, see your doctor; your dose may be too high. Diuretics can have other side-effects. They may drive potassium out in your urine. This may cause weakness. Your doctor will occasionally check your potassium level. He or she may need to add potassium tablets. Your doctor can also add another diuretic like amiloride or spironolactone: these drugs reverse the loss of potassium. Some drug companies produce a single tablet which contains both types of diuretic. Commonly used examples are Moduretic and Frumil. Some diuretics cause nausea, constipation or headache, and some may give you a rash. They can also occasionally trigger an attack of gout. If your thirst is persistent, it is possible that you have developed diabetes, which is one of the side-effects of most diuretics: your doctor will check your blood or urine for sugar. If you are diabetic already, your water tablet can make your diabetes go out of control. Do see your doctor if any of these or any other problems occur.

Drug Interference

If you are having other tablets for high blood pressure, in particular the so called ACE inhibitors (whose names usually end with "...pril") your blood pressure may fall too far. It may also do this with some drugs used to treat depression. You may then feel dizzy and unsteady. The low blood potassium level mentioned earlier can cause heartbeat irregularity if you happen to be taking digoxin or amiodarone as well. If you are taking lithium for depression, its dose may need to be reduced. All diuretics increase the activity of some anti-inflammation tablets: their dose may need to be reduced too. In turn, the anti-inflammation tablet may reduce the effect of the diuretic so that it does not work so efficiently. If you happen to be on aspirin, the diuretic spironolactone will not work properly: you will need a different drug. As mentioned above, by raising the blood sugar level, anti-diabetic tablets are made less effective.

What if Diuretics are not taken ?

If you stop taking the diuretic without your doctor's advice, any symptoms you had will return. If it was being taken for high blood pressure, this would rise again, but you would not feel anything. If you forget a dose, it is better to just make sure you take the next day's dose. Taking doses too close to each other could give an effect which is too sudden. At the very least it may keep you up at night, passing urine!

General advice about Diuretics

Tell your doctor if you are pregnant or breast-feeding: ideally diuretics should be avoided, since they very occasionally can harm the baby. If you have any questions not answered by this leaflet, please ask your pharmacist or doctor. Keep this leaflet handy in case you need to refer to it again.