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Diuretics are used to treat high blood pressure and heart failure and are usually combined with other medications.

How does it work?
Diuretics act on your kidneys to produce more urine and remove excess salt and water from your body. By decreasing water and salt, diuretics lower your blood pressure and help reduce the workload on your heart and this can help heart failure patients. This may make it easier for your heart to pump, make you feel less short of breath, reduce swelling and bloating, reduce the time you spend in hospital and help you live longer.

How should I take it?
Since diuretics work on the kidney to make more urine, you will find you have to go to the bathroom more often. It may help if you take your diuretic at least six hours before bedtime so that you do not have to get up during the night. Always talk to your doctor or pharmacist about how and when to take your medication.

What should I avoid while taking this medicine?
Limit the amount of salt you consume. Do not use salt substitutes without first talking to your doctor or pharmacist. Talk with your doctor or health professional about whether you should restrict the amount of fluids you drink. If you drink alcohol, limit the amount you drink to reduce the chances of dizziness or fainting. A diuretic called furosemide may cause your skin to be more sensitive to sunlight, so protect yourself against sunburn.

What if I am taking other medicines?
Always tell your doctor and pharmacist about any other medication you are taking including prescription, non-prescription, over-the-counter or natural health products (vitamins and minerals, herbal remedies, homeopathic medicines, traditional medicines such as traditional Chinese medicines, probiotics and other products such as amino acids and essential fatty acids).

What else should I tell my doctor?
Some diuretics can cause you to lose potassium. Ask your doctor or pharmacist whether you should eat foods rich in potassium or take a potassium supplement. If you are on other medications that retain potassium, you may not need extra potassium. You may be instructed to weigh yourself daily or every other day to check for rapid weight gain that may signify water retention.

What are some side effects?
Most people have no problems taking a diuretic. Call your doctor or pharmacist if you experience side effects such as signs of dehydration including low urine production, dry mouth, decreased skin springiness, muscle cramps, weakness, fever, sore throat or skin rash. You may experience some less common side effects including dizziness, lightheadedness or upset stomach. If these become serious, report them to your doctor. Speak to your doctor about any side effects you experience.

Lifestyle changes
Eating a healthy diet that is lower in fat, especially saturated and trans fats, being smoke free, limiting alcohol use, being physically active and reducing stress are also important in lowering the risk of heart disease. Talk to your healthcare practitioner about how you can achieve these lifestyle changes.

For more information
Health Canada provides health and medical information to help Canadians maintain and improve their health. Learn more about Safe Use of MedicinesSafety and Effectiveness of Generic Drugs and Buying Drugs over the Internet.

Drug Product Database provides information about drugs approved for use in Canada.

MedEffect Canada provides safety alerts, public health advisories, warnings and recalls.

Your ministry of health also provides useful health resources in your province or territory. For example, Ontario has a MedsCheck program providing free pharmacist consultations on safety use of drugs. British Columbia has a Senior Healthcare webpage providing information about important health programs.  

Last modified: July 2011
Last reviewed: July 2011