Diuretics, also known as water pills, are medicines that help reduce the amount of water in the body. They treat the buildup of excess fluid in the body that occurs with some medical conditions such as congestive heart failure, liver disease, and kidney disease. Some diuretics are also prescribed totreat high blood pressure. They act on the kidneys to increase urine output,reducing fluid in the bloodstream, in turn lowering blood pressure.

There are several types of diuretics. Loop diuretics, such as bumetanide (Bumex) and furosemide (Lasix), get their name from the loop-shaped part of the kidneys where they have their effect. Thiazide diuretics include such commonlyused diuretics as hydrochlorothiazide (HydroDIURIL, Esidrix), chlorothiazide(Diuril), and chlorthalidone (Hygroton). Potassium-sparing diuretics preventthe loss of potassium, a problem with other type pes of diuretics. Examplesare amiloride (Midamor) and triamterene (Dyrenium). In addition, some medicines contain combinations of two diuretics.

Some nonprescription (over-the-counter) medicines contain diuretics. However,the medicines described here cannot be bought without a physician's prescription. Seeing a physician regularly while taking a diuretic is important.

Some people feel unusually tired when they first start taking diuretics. Thiseffect usually becomes less noticeable over time, as the body adjusts to themedicine. Because diuretics increase urine output, users may need to urinatemore often.

For patients taking the kinds of diuretics that rob potassium from the body,physicians may recommend adding potassium-rich foods or drinks, such as citrus fruits and juices, to the diet. Or they may suggest a potassium supplementor another medicine that reduces potassium loss. Do not make diet changes without checking with the physician. People who are taking potassium-sparing diuretics should not add potassium to their diets, as too much potassium may beharmful.

People who take diuretics may lose too much water or potassium when they getsick, especially if they have severe vomiting and diarrhea. They should checkwith their physicians if they become ill.

These medicines make some people feel lightheaded, dizzy or faint when they get up after sitting or lying down. Older people are especially likely to havethis problem. Drinking alcohol, exercising, standing for long periods or being in hot weather may make the problem worse.

Anyone who is taking a diuretic should be sure to tell a health care professional before having surgical or dental procedures, medical tests or emergencytreatment.

Some diuretics make the skin more sensitive to sunlight. Even brief exposureto sun can cause a severe sunburn, itching, a rash, redness, or other changesin skin color.

Anyone who has had unusual reactions to diuretics or sulfonamides (sulfa drugs) in the past should let his or her physician know before using a diuretic.The physician should also be told about any allergies.

Diuretics will not help the swelling of hands and feet that some women have during pregnancy. In general, pregnant women should not use diuretics unless aphysician recommends their use. Women who are breastfeeding and need to usea diuretic should check with their physicians.

Side effects of some diuretics may be more likely in people who have had a recent heart attack or who have liver disease or severe kidney disease. Other diuretics may not work properly in people with liver disease or severe kidneydisease. Diuretics may worsen certain medical conditions, such as gout, kidney stones, pancreatitis, lupus erythematosus and hearing problems. In addition, people with diabetes should be aware that diuretics may increase blood sugar levels. People with heart or blood vessel disease should know that some diuretics increase cholesterol or triglyceride levels. The risk of an allergic reaction to certain diuretics is greater in people with bronchial asthma. Also, people who have trouble urinating or who have high potassium levelsin their blood may not be able to take diuretics.

Some side effects, such as loss of appetite, nausea and vomiting, stomach cramps, diarrhea and dizziness, usually lessen or goaway as the body adjusts to the medicine. These problems do not need medicalattention unless they continue or interfere with normal activities.

Patients taking potassium-sparing diuretics should know the signs of too muchpotassium and should check with a physician if any of these symptoms occur:

  • Irregular heartbeat
  • Breathing problems
  • Numbness or tingling in the hands, feet or lips
  • Confusion or nervousness
  • Unusual tiredness or weakness
  • Weak or heavy feeling in the legs.

Patients taking diuretics that cause potassium loss should know the signs oftoo little potassium and should check with a physician if they exhibit:

  • Fast or irregular heartbeat
  • Weak pulse
  • Nausea or vomiting
  • Dry mouth
  • Excessive thirst
  • Muscle cramps or pain
  • Unusual tiredness or weakness
  • Mental or mood changes.

Anyone who takes a diuretic should let the physician know all other medicineshe or she is taking and should ask about possible interactions. Among the drugs that may interact with diuretics are:

  • Angiotensin-converting enzyme (ACE) inhibitors such as benazepril (Lotensin), captopril (Capoten) and enalapril (Vasotec).
  • Cholesterol-lowering drugs such as cholestyramine (Questran) and colestipol (Colestid).
  • Cyclosporine (Sandimmune), a medicine that suppresses the immune system.
  • Potassium supplements, other medicines containing potassium, or salt substitutes that contain potassium.
  • Lithium.
  • Digitalis heart drugs, such asdigoxin (Lanoxin).

The list above does not include every drug that may interact with diuretics.Check with a physician or pharmacist before combining diuretics with any other prescription or nonprescription (over-the-counter) medicine.

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