Diuretics are often called water pills. They affect the balance of fluid in your body. Diuretics make the kidneys:

  • Create more urine
  • Pass more water, salt, and electrolytes (sodium, potassium, calcium) out of the body

They can be used to help manage many health issues. The most common are heart disease, kidney disease, or high blood pressure. There are different types of diuretics including:

  • Loop diuretics—used in people with kidney problems.
  • Potassium-sparing diuretics—helps to keep potassium in the body. Some people have or are at risk for low potassium levels. Other diuretics can make it worse.
  • Thiazide diuretics—one of the most common to treat high blood pressure.
  • Combination of potassium-sparing and thiazide (hydrochlorothiazide)

What They Are Prescribed For

Diuretics may be prescribed to treat:

Precautions While Taking a Diuretic

Your doctor may start with a small amount of medicine. The amount will be increased step by step until it improves your health. It will be important to see your doctor as planned. This will help your doctor find the amount of medicine that is best for you. The amount of medicine may also need to be changed if you have strong side effects.

Diuretics will affect how your body reacts. Let your doctor or dentist know about any medicine you are taking. Share this info with your care team. Let them know before surgery, dental work, or other medical care.

Some diuretics can cause you to lose too much potassium. This is most true with thiazide and loop diuretics. To help you keep a healthy potassium level, your doctor may recommend that you:

  • Choose foods and drinks that are high in potassium. Examples include:
    • Most fruits and vegetables such as dried figs, potatoes, bananas, oranges, and raisins
    • Legumes such as black beans, lentils, chickpeas
  • Take a potassium supplement
  • Switch to a potassium-sparing diuretic

Other steps that may help include:

  • Let your doctor know if you are having stomach problems. Severe vomiting or diarrhea can lower your potassium levels.
  • Talk to your doctor before you make big changes to your diet.

Not all diuretics cause a loss of potassium. Changes to your diet may not be needed.

Diuretics are not useful for swelling from pregnancy. They should not be taken during pregnancy unless your doctor says it is safe.

Diuretics are not used for mothers who are breastfeeding. Some medicine can pass to the baby through breastmilk.

Tell your doctor about any medicine you are taking. Some should not be taken with diuretics. Others may need to be adjusted.

Over-the counter medicine can cause some problems. Check with your doctor before taking any other medicine. Cold, cough, and allergy medicine can cause problems for people with high blood pressure.

Other health issues can also affect how you respond to medicine. Make sure your doctor is aware of any other health issues you have. This includes diabetes, kidney, liver, heart, and immune system problems.

Diuretics can sometimes cause dizziness. It is most common when you get up from a lying or sitting down. It can sometimes lead to fainting.

Try to slow down when getting up. Alcohol, standing for a long time, intense exercise, or hot weather can make it worse. Tell your doctor if the problems happen often or get worse.

Your skin may become more sensitive to the sun. This may lead to a rash, itch, redness, or sunburn. It may occur even after short periods of time in the sun. To help protect your skin:

  • Stay out of direct sunlight. The sun is most intense 10:00 a.m. and 3:00 p.m.
  • Wear protective clothing. This includes a hat and sunglasses.
  • Apply a broad-spectrum sunscreen and lip balm with at least 30 SPF.
  • Do not use a sunlamp or tanning booth.

Tell your doctor if you have had a severe reaction to the sun.

Dosing and Missed Doses

Take each dose at the same time each day. The medicine will make you urinate more. Try to take it early in the day so that it does not wake you up at night to urinate.

  • If you take a single dose, take it after breakfast.
  • If you take more than one dose, take the last dose no later than 6:00 pm.

Medicine can sometimes upset your stomach. In this case, try to take it with food or drink. Tell your doctor if stomach upset continues or gets worse. Also, let your doctor know if you have sudden, severe diarrhea.

If you miss a dose, take it as soon as possible. If it is almost time for your next dose, skip the missed dose. Go back to your schedule. Do not double doses.

Possible Side Effects

Side effect can vary among the different types of diuretics but may include:

  • Dehydration—too much fluid is lost from the body
  • Hypokalemia—too little potassium in the blood
  • Hyperkalemia—too much potassium in the blood
  • Hyponatremia—too little sodium in the blood

Most will do well on diuretics. If you are having problems talk to your doctor. Changing the amount may help. Your doctor may also recommend a different medicine.