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Diuretics Q&As

Published by Bupa's health information team, April 2009.

Answers to questions about diuretics

This section contains answers to common questions about this topic. Questions have been suggested by health professionals, website feedback and requests via email.

I have been diagnosed with glaucoma. Why has my doctor prescribed a diuretic?

Glaucoma is a group of eye conditions in which your optic nerve can become damaged at the point where it leaves your eye. Glaucoma is caused by too much fluid in the eye which increase the pressure inside it. If you have glaucoma, diuretics such as acetazolamide may be used to reduce the amount of fluid in your affected eye and maintain a healthy eye pressure.

Explanation

Your eye is filled with a watery substance (aqueous humour) which creates pressure in the eye to give it shape. This watery substance has nothing to do with your tears. In a healthy eye, this fluid constantly flows in and out of the eye to nourish it. Eye pressure is maintained by this fluid moving back and forth between your eye and your bloodstream at the same rate.

You can get glaucoma when the movement of fluid is disrupted - more fluid remains in the eye causing an increase in pressure. It's this increase in pressure which can eventually damage your optic nerve and cause blindness. Your optic nerve plays an important role in carrying information from the back of your eye (retina) to the brain where it's processed as an image. It's important to realise that your eye pressure is largely independent of your blood pressure.

The aim of treatment for glaucoma is to reduce the pressure in the affected eye. Different types of medicine are available to treat glaucoma. These include beta-blockers (as eye drops), prostaglandins and diuretics. Your GP may prescribe a diuretic such as acetazolamide to reduce the pressure in the eye caused by this condition. Diuretics work by reducing the amount of water and salt that is re-absorbed by your kidneys. So, more water and salt passes out with the waste products into your urine. As a result of this loss of water from the blood, the overall volume of blood is reduced and your eye pressure can be reduced to a healthy level.

Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.

Further information

Sources

  • Understanding glaucoma. Royal National Institute of Blind People (RNIB). www.rnib.org.uk, accessed 18 August 2008
  • Joint Formulary Committee, British National Formulary. 56th ed. London: British Medical Association and Royal Pharmaceutical Society of Great Britain, 2008:580; 583-584
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I regularly suffer from bloating when I am having my period. Would diuretics help?

There is no evidence to suggest that diuretics (also known as 'water tablets') should be regularly prescribed to remove excess fluid from your body during your period. Mild diuretics may be helpful for relieving fluid retention and feelings of being bloated in the week or two before a period. Consider other methods of controlling bloating such as exercise, diet and the use of natural diuretics (eg asparagus, parsley, celery) instead. Your GP will be able to advise you on the best ways to reduce bloating.

Explanation

Many women feel bloated around the time of their period. Bloating may form part of the premenstrual syndrome, a group of physiological, psychological and emotional symptoms that can occur just before a period starts. Other symptoms include mood swings and breast tenderness.

Bloating has several causes, but is typically caused by water retention resulting from the action of your hormones just before your period starts. Other causes include:

  • too much salt in your diet
  • regular use of some common medicines (eg contraceptive pill)
  • periods of immobility (eg standing for long periods of time)

Diuretics ('water tablets') may be helpful for relieving fluid retention, feeling bloated and weight gain in the week or two after a period. Your GP may prescribe diuretics; you can also buy some diuretics from your pharmacist. However, there is no evidence to suggest that diuretics should be taken regularly to remove excess fluid from your body during your period.

Diuretics work by reducing the amount of water and salt that is re-absorbed by your kidneys. This means that more water and salt passes out with the waste products into your urine. If you take diuretics, you may get side-effects such as feeling faint or dizzy when you stand up suddenly. Diuretics can also upset the balance of minerals in your body, leading to low levels of potassium (hypokalaemia) and sodium (hyponatraemia), and reduced levels of body water (dehydration).

Always ask your GP for advice and read the patient information leaflet that comes with your medicine.

You may be able to control your bloating by taking regular exercise or changing your diet. Taking a natural diuretic such as asparagus, parsley or celery, reducing salt intake and increasing the amount of water you drink can also help.

Your GP will be able to advise you on the best ways of managing your bloating. Always let him or her know if you're taking any dietary or herbal supplements for water retention, as these might cause reactions with any prescribed medicines.

Further information

  • National Association for Premenstrual Syndrome
    0870 777 2177
    www.pms.org.uk

Sources

  • Physical symptoms. National Association for Premenstrual Syndrome. www.pms.org.uk, accessed 19 August 2008
  • Simon C, Everitt H, Kendrick T. Oxford Handbook of General Practice. 2nd ed. Oxford: Oxford University Press, 2007:339
  • Joint Formulary Committee, British National Formulary. 56th ed. London: British Medical Association and Royal Pharmaceutical Society of Great Britain, 2008:72-78
  • Warrell DA, Cox TM, Firth JD. Oxford Textbook of Medicine. 4th ed. Vol 2. Oxford: Oxford University Press, 2005;961-962
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Are there any medicines, supplements, foods or drinks I shouldn't have if I'm taking diuretics?

Diuretics can interact with a number of different medicines. Before taking a diuretic, you should always tell your doctor if you're taking any medicines (prescribed or bought at a pharmacy) or herbal, vitamin and mineral supplements. This will help to prevent any drug interactions, which may be harmful or could affect the effectiveness of your diuretic or other medicines.

Explanation

Diuretics are often prescribed in combination with other medicines, particularly ones that you might need for heart problems. If you need to take a diuretic and are already taking other medicines, there is a chance that your medicines may interact with each other. These interactions may affect the effectiveness of one or more of your medicines and may cause some of your symptoms to return. The interactions may also cause side-effects. You may be at increased risk from medicine interactions if you're elderly or have kidney or liver problems.

There are a lot of medicines that you might be taking which can be affected when you also take diuretics. Medicines affected by diuretics include:

  • antibiotics (eg vancomycin)
  • painkillers (eg aspirin)
  • beta-blockers (eg sotalol)
  • anti-arrhythmic medicines (eg lidocaine)
  • antidepressants

If you're prescribed more than one type of diuretic, for example a thiazide diuretic and a loop diuretic, this can upset the balance of minerals in your body, leading to low levels of potassium (hypokalaemia). If you're taking other medicines for any heart problems, low levels of potassium may cause you to have irregular heartbeats. Your doctor may prescribe a potassium supplement so that you maintain healthy levels of potassium. Only take these as prescribed by your doctor. Always check with your doctor before taking any other vitamin supplements at the same time as your diuretics.

You may need to stop drinking alcohol when taking diuretics as this may cause your blood pressure to decrease below your usual levels. You may also need to stop taking certain vitamin supplements. For example, calcium or vitamin D supplements (or foods high in either of these) may cause high levels of calcium if taken with thiazide diuretics.

Before a diuretic is prescribed, you should tell your doctor if you're taking any other medicines that have been prescribed or bought at a pharmacy or any herbal, vitamin or mineral supplements. This information will enable your doctor to choose the right diuretic for you. Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.

Further information

Sources

  • Joint Formulary Committee, British National Formulary. 56th ed. London: British Medical Association and Royal Pharmaceutical Society of Great Britain, 2008:72-78
  • Warrell DA, Cox TM, Firth JD. Oxford Textbook of Medicine. 4th ed. Vol 2. Oxford: Oxford University Press, 2005:961-962
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This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: April 2009

 

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