7 Amiloride Side Effects You Should Know About

Amiloride (Midamor) is a prescription medication used to treat high blood pressure and fluid buildup caused by heart failure. It’s part of a group of medications known as diuretics, and it’s usually taken along with another diuretic, such as hydrochlorothiazide.

Amiloride works by helping the kidneys remove excess water from the body. This helps lower blood pressure and can lessen swelling. Amiloride also helps your body hold onto potassium. Because of this, it’s often used along with diuretics that can cause low potassium levels in order to help keep your levels normal.

Like most medications, amiloride may cause side effects, some of which can be serious. Below are seven amiloride side effects to look out for and how to manage them.

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1. Headache

Headache is one of the more common side effects of amiloride. Up to 8% of people in clinical trials reported a headache. This can happen as a result of blood pressure changes caused by amiloride. While headaches can be frustrating and affect your work and personal life, they tend to go away as your body adjusts to the medication.

In the meantime, it may be helpful to take over-the-counter (OTC) pain medications like acetaminophen (Tylenol) or ibuprofen (Advil). Also, make sure you’re staying hydrated, because not drinking enough water can also cause headaches.

If you have headaches that are severe or won’t go away, talk to your healthcare provider. 

2. Nausea and vomiting

Nausea and low appetite occurred in 3% to 8% of people taking amiloride in clinical trials. Nausea may sometimes lead to vomiting. These side effects should subside over time as your body gets used to the medication. It’s recommended to take amiloride with a small snack or meal. This may help prevent nausea. There are OTC medications available to help treat nausea, such as bismuth subsalicylate (Pepto-Bismol). Ask your healthcare provider or pharmacist if one of these is an option for you.

Nausea could also be a sign of high potassium levels in your body. So if you have nausea that doesn’t improve or are vomiting, talk to your healthcare provider. They may need to check your potassium levels and make changes to your medication.

3. Diarrhea

You may experience diarrhea while taking amiloride. This side effect can affect your quality of life and lead to other health issues, like dehydration. 

Be sure to stay hydrated by drinking plenty of fluids if you have diarrhea. Following a diet that’s easy on your stomach can help improve symptoms. The BRAT diet is a popular option to consider for short-term use. BRAT is an acronym that stands for bananas, rice, applesauce, and toast. Following the BRAT diet can help make your stools firmer. 

If your healthcare provider says it’s OK, there are OTC medications you can use to treat diarrhea in the short term, such as loperamide (Imodium A-D). But be sure to seek medical attention right away if you have severe or bloody diarrhea, stomach pain, or fever.

4. Dizziness

Amiloride can cause feelings of dizziness. This is common for medications that lower blood pressure. Dizziness can worsen nausea and can cause loss of balance, leading to falls. This risk might be higher if you have a history of falls or are over the age of 65.

Move slowly when you stand or sit up if you’re taking amiloride — especially in the first few weeks. Slow movements can help your body adjust to changes in blood pressure and lessen the risk of falls. If you feel lightheaded when standing, sit down right away. 

Talk to your healthcare provider if your dizziness doesn’t go away or worsens. Your blood pressure may be too low, or there could be something else causing the dizziness.

5. Leg cramps

Muscle cramps and weakness may occur while taking amiloride. This is because amiloride changes the fluid and electrolyte levels in your blood. Low levels of the electrolytes magnesium, potassium, and calcium can make muscle cramps more likely. Stretching and proper hydration may relieve the symptoms of muscle cramps.

If you have ongoing cramps or experience any numbness or tingling, talk to your healthcare provider. These could be signs of a more serious electrolyte imbalance.

6. High potassium levels

The FDA has given a boxed warning (the most serious type of side effect warning) about the potential for amiloride to cause high levels of potassium. High potassium levels can lead to heart rhythm problems, which can become a serious medical emergency. People with certain medical conditions, such as kidney disease, may have a greater risk of high potassium levels.

It’s best to avoid amiloride if you take other medications known to cause high potassium, such as lisinopril (Zestril) or losartan (Cozaar). Nonsteroidal anti-inflammatory drugs (NSAIDs) may also make high potassium more likely. Make sure to give your healthcare provider or pharmacist a complete list of the medications you take. They can tell you if it’s safe for you to take amiloride.

Try to avoid eating too much food that is high in potassium while taking amiloride. Melons, orange juice, and bananas are among the foods you may want to limit. Check with your healthcare provider or pharmacist before using any salt substitutes. Some of these products contain extra potassium.

You might not notice symptoms of high blood potassium, but muscle weakness or nausea can be signs that your potassium levels are outside the normal range. 

Contact your healthcare provider right away if you notice:

• Heart palpitations

• Confusion

• Shortness of breath

• Chest pain

• Vomiting

Your healthcare provider will regularly check your potassium levels with a simple blood test. Make sure to keep your scheduled appointments so they can monitor for this important side effect.

7. High uric acid levels

Amiloride can increase levels of uric acid in your body (hyperuricemia). This is more likely if you’re taking amiloride for an extended period of time. A lot of the time, you won’t notice any symptoms of hyperuricemia. But in some people it may cause a condition known as gout.

Staying properly hydrated while taking amiloride can help reduce the chance of this side effect. Some people have limits on how much fluid they should consume each day, so make sure you know the right amount for you.

Symptoms of gout include pain, redness, and swelling of a joint — most often the knee or a big toe. Let your healthcare provider know if you develop signs of gout. They may need to change your medication or provide additional treatment.

When should I contact my healthcare provider about amiloride side effects?

The most common amiloride side effects often improve within the first few weeks of starting the medication. But you should discuss any symptoms that are bothersome or don’t go away with your healthcare provider.

Seek medical care right away if you experience the following:

• Signs of an allergic reaction, such as rash or hives

• Swelling

• Confusion

• Severe diarrhea

• Heart palpitations

• Chest pain

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Written by:

Justin DeFlorian, PharmD, BCPS

Justin DeFlorian, PharmD, BCPS, is a board-certified clinical pharmacist. He received his Doctor of Pharmacy degree from the University of Wisconsin-Madison.

Edited by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

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