9 Side Effects of Diuretics: Frequent Bathroom Trips, Potassium Changes, and More

Diuretics (water pills) are popular prescription medications that have been around for over 70 years. They include a variety of types, such as thiazides, loop diuretics, and more. Hypertension (high blood pressure) and edema (fluid buildup) are two of the many health conditions they treat.

They’re typically well tolerated, but diuretics have side effects to be aware of.

Diuretic side effects at a glance

Like all medications, diuretics can cause side effects. The good news is most side effects tend to be mild. They may get better or become unnoticeable as your body gets used to the medication. Side effects also vary depending on the diuretic you’re taking.

Relatively common side effects of diuretics include:

• Dizziness

• Nausea

• Vomiting

• Diarrhea

• Hypotension (low blood pressure)

• Breast pain or tenderness

• Headache

• Frequent urination

• Dry mouth

• High blood glucose (sugar) levels

• Fatigue

• Changes in potassium levels

• Muscle cramps

• Sexual problems

• Sun sensitivity

Rare but potentially serious diuretic side effects include:

• Dehydration

• Kidney damage

• Very high or low electrolyte levels

• Hearing problems

• Serious skin rash

• Pancreatitis (pancreas inflammation)

Below, we’ll focus on nine diuretic side effects and safety tips to manage them.

1. Frequent bathroom trips

You probably notice you’re peeing more after you start a diuretic. This is completely normal, considering the way they work. Diuretics — such as hydrochlorothiazide (Microzide) and furosemide (Lasix) — work in the kidneys to remove extra fluids through your urine.

This effect is beneficial overall. But it could disrupt your sleep if you’re frequenting the bathroom in the middle of the night.

EXPERT PICKS: WHAT TO READ NEXT

• Taking hydrochlorothiazide: Pharmacists discuss recommended hydrochlorothiazide (Microzide) dosages for adults and kids.

• Furosemide safety: Learn from pharmacists about common furosemide (Lasix) side effects and how to manage them.

• Hypertension stories: Hear from real people about their experiences with hypertension (high blood pressure) and how to manage it.

It’s best to take your diuretic dose in the morning to prevent nighttime bathroom trips. If your medication requires more than one dose, try taking your last pill in the early afternoon.

2. Headaches

Headaches are a common diuretic side effect, as they are with many medications. They should get better as you get used to your medication. Nevertheless, it helps to have tools to manage them.

Make sure you’re staying hydrated by drinking enough fluids. Dehydration can cause headaches. Other diuretic side effects could also be culprits of a bothersome headache. Electrolyte changes and hypotension are two examples.

You can try managing your headache at home with an over-the-counter pain reliever such as acetaminophen (Tylenol). But it’s a good idea to check with your prescriber or pharmacist to make sure it’s safe for you.

3. Dizziness

Blood pressure medications, such as diuretics, may cause your blood pressure to drop too low. This can lead to dizziness. Dehydration and changes in your electrolytes could also be contributing factors.

As your body gets used to your diuretic, dizziness should improve. Here are some tips to help prevent and manage dizziness in the meantime:

• Stay hydrated.

• Have a snack if you’re hungry.

• Sit or lie down if you feel dizzy.

• Avoid alcohol.

• Check your blood pressure.

If your dizziness gets worse or doesn’t improve, talk to a healthcare professional. Seek emergency care right away if you experience serious symptoms, such as fainting and seizures, along with dizziness.

4. Dry mouth and dehydration

Dry mouth is a hallmark symptom of dehydration, especially if you’re taking a diuretic. Make sure you’re consuming enough fluids on a daily basis to help combat this. Watermelon and cucumbers are a couple of hydrating foods that can also make a difference.

Dehydration is common, but it can take a turn for the worse in some cases. If you experience signs of severe dehydration, go to the ER. Confusion, very dry skin, and little or no urine are some telltale symptoms.

Good to know: It’s a good idea to limit how much alcohol you drink while taking a diuretic. Alcohol makes you pee more, which can exacerbate dehydration.

5. Sun sensitivity

It’s always a good idea to protect yourself from the sun’s rays, especially if you’re taking certain diuretics.

Sun sensitivity is one of the more surprising side effects of diuretics. This means you have a greater risk of getting a sunburn while you’re taking one. It’s more common with hydrochlorothiazide and furosemide compared with other diuretics.

There have also been reports of eczema rashes and other skin problems among people taking hydrochlorothiazide who are exposed to the sun. These sun-sensitivity reactions sometimes lasted months to years after stopping the medication.

There are steps you can take to protect your skin before heading outdoors. These include applying sunscreen, wearing a hat, and staying in the shade.

6. High or low potassium levels

Potassium is an important electrolyte your body needs. It helps support your heart, kidneys, muscles, and more. Diuretics can sometimes disrupt your potassium balance, though. Thankfully, your potassium levels can be easily checked with a blood test.

Low potassium levels

Thiazide diuretics like hydrochlorothiazide can cause hypokalemia (low potassium levels). That’s because you can lose potassium through your pee.

Loop diuretics like furosemide can also cause hypokalemia. In fact, a healthcare professional will likely check your potassium levels often during the first few months of starting furosemide and periodically after that.

Potassium-rich foods, such as avocados, lentils, and squash, can help boost your potassium levels. If your levels are very low, a healthcare professional may recommend a potassium supplement to get them on track.

Muscle cramps and constipation are possible symptoms of hypokalemia. Shortness of breath and abnormal heart beat are more serious warning signs to seek emergency care right away.

High potassium levels

Spironolactone (Aldactone) is a potassium-sparing diuretic. It prevents you from losing potassium when you pee. That’s why hyperkalemia (high potassium levels) is a possible spironolactone side effect.

Typically, a healthcare professional will check your potassium levels within 7 days (1 week) of starting spironolactone. They should also check them routinely while you’re taking it. If your potassium levels jump too high, your prescriber may lower your spironolactone dosage.

Hyperkalemia is usually mild with spironolactone, but it’s a good idea to watch for serious symptoms like chest pain and heart palpitations. These are warning signs to seek emergency medical care immediately.

Good to know: Hyperkalemia is more likely to happen if you’re taking other medications that also raise your potassium levels. Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil, Motrin) are one example. Angiotensin-converting enzyme (ACE) inhibitors, such as lisinopril (Zestril), are another. It’s best to keep an updated list of your medications handy. Your pharmacist and prescriber can screen for potential interactions.

7. Other electrolyte changes

Potassium aside, diuretics can change the balance of other electrolytes in your blood.

Thiazide and loop diuretics can cause hyponatremia (low sodium levels). Between the two, it’s more likely to happen with thiazides. People typically start experiencing symptoms when sodium levels drop below 120 mEq/L. Nausea, fatigue, and dizziness are a few common symptoms of hyponatremia, but it may not cause any noticeable symptoms. A healthcare professional can perform a blood test to check your sodium levels.

Thiazide diuretics can also cause high calcium and low magnesium levels. Loop diuretics can lower calcium and chloride levels.

8. Low blood pressure

Diuretics lower blood pressure. This is intentional, but sometimes they can do too much and cause hypotension. This is more likely to happen when you first start your medication.

Check your blood pressure at home to keep track of your readings. If you’re frequently seeing readings less than 90/60 mm Hg, it’s a good idea to talk to a healthcare professional. Your diuretic dosage may need to be lowered.

9. Kidney damage

In rare cases, diuretics can negatively affect your kidneys. This can affect how well your kidneys filter waste products.

Certain factors put you at higher risk for kidney damage. Living with kidney problems and being an older adult are at the top of the list. A healthcare professional can run blood tests to check how well your kidneys are working while you’re taking a diuretic.

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Written by:

Jennifer Gershman, PharmD, CPh, PACS

Jennifer Gershman, PharmD, is a licensed pharmacist in Florida. She has worked in the pharmacy industry for more than 15 years and is currently a medical writer.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Soojin Jun, PharmD, BCGP

Soojin has 10 years of experience in various pharmacy settings, from inpatient to outpatient settings, and population health in value-based healthcare models. She completed training in various areas of healthcare to ensure patient safety, from activism, geriatric pharmacy, medication safety, healthcare quality, patient safety, death and dying, and trauma-informed care.

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