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Thiazides, potassium-sparing, loop-acting


The information in this Medicines for Cardiovascular Disease section has been taken from a number of sources. It is meant to give you information about certain medicines, but it does not cover all of the possible uses, warnings, side effects, or interactions with other medicines and vitamin or herbal supplements. This information should not be used as medical advice for individual problems. Please talk to your doctor and/or your pharmacist for prescription instructions.

Why do I need to take a diuretic?

Diuretics are sometimes called "water pills." They are used to treat congestive heart failure (CHF), high blood pressure (hypertension), or edema (water retention). Diuretics are also prescribed for certain kinds of kidney or liver diseases.

How do diuretics work?

There are 3 types of diuretic medicines. Each type works a little differently, but they all lower the amount of salt and water in your body, which helps to lower your blood pressure.

1. Thiazide diuretics are used to treat high blood pressure by reducing the amount of sodium and water in the body. Thiazides are the only type of diuretic that dilates (widens) the blood vessels, which also helps to lower blood pressure.

2. Potassium-sparing diuretics are used to reduce the amount of water in the body. Unlike the other diuretic medicines, these medicines do not cause your body to lose potassium.

3. Loop-acting diuretics cause the kidneys to increase the flow of urine. This helps reduce the amount of water in your body and lower your blood pressure.

How much do I take?

There are many different kinds of diuretics. The amount of medicine that you need to take may vary. Talk to your doctor or pharmacist for more information about how and when to take this medicine.

What if I am taking other medicines?

Other medicines that you may be taking can increase or decrease the effect of diuretics. These effects are called an interaction. Be sure to tell your doctor about every medicine and vitamin or herbal supplement that you are taking, so he or she can make you aware of any interactions.

The following are some of the medicines that can interact with diuretics. Because there are so many kinds of medicines within each category, not every type of medicine is listed by name. Tell your doctor about every medicine that you are taking, even if it is not listed below.

  • Digitalis and digoxin, especially if your potassium level is low
  • Certain antidepressants, especially when taking thiazide or loop-acting diuretics
  • Other medicines for high blood pressure
  • Lithium
  • Cyclosporine, especially when taking a potassium-sparing diuretic

What else should I tell my doctor?

Talk to your doctor about your medical history before you start taking a diuretic. The risks of taking the medicine need to be weighed against its benefits. Here are some things to consider if you and your doctor are deciding whether you should take a diuretic.

  • You have allergies to other medicines.
  • You are thinking of becoming pregnant, you are pregnant, or you are breast feeding your baby.
  • You have diabetes. Thiazide and loop-acting diuretics can increase your blood sugar levels.
  • You become dehydrated easily.
  • You have pancreatitis. Loop-acting diuretics can make this condition worse.
  • You have kidney problems.
  • You have lupus or a history of lupus. Thiazide diuretics can make this condition worse.
  • You have gout or are at high risk for developing gout, especially if your doctor is going to prescribe a thiazide diuretic.
  • You have menstrual problems. Potassium-sparing diuretics can make these problems worse.

What are the side effects?

Sometimes a medicine causes unwanted effects. These are called side effects. Not all of the side effects for diuretics are listed here. If you feel these or any other effects, you should check with your doctor.

Common side effects:

  • Weakness
  • Muscle cramps
  • Skin rash
  • Increased sensitivity to sunlight (with thiazide diuretics)
  • Throwing up
  • Diarrhea
  • Cramps
  • Dizziness or lightheadedness
  • Joint pain

Less common side effects:

  • Impotence or decreased sexual desire

Rare side effects:

  • Irregular heartbeat (arrhythmia)

Again, tell your doctor right away if you have any of these side effects. Do not stop taking your medicine unless your doctor tells you to. If you stop taking your medicine without checking with your doctor, it can make your condition worse.

See on other sites:

Heart failure - fluids and diuretics
A consumer-based site by the American Society of Health-System Pharmacists that provides information about all types of medicines as well as safety tips for their proper use. The site's search feature lets users search medicines by the brand or generic name.

Updated August 2016
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