Inspra (Eplerenone) – Oral

What Is Inspra?

Inspra (eplerenone) is an oral prescription medication used to treat heart failure and high blood pressure.

Inspra belongs to a group of drugs called aldosterone antagonists. These medications work by blocking aldosterone—a naturally occurring chemical in your body that causes fluid retention and increases blood pressure. Inspra is also considered a potassium-sparing diuretic since it removes excess fluid from your body without depleting potassium.

Drug Facts

Generic Name: Eplerenone

Brand Name(s): Inspra

Administration Route(s): Oral

Drug Availability: Prescription

Therapeutic Classification: Cardiovascular agent

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Eplerenone

Dosage Form(s): Tablet

What Is Inspra Used For?

The Food and Drug Administration (FDA) approved Inspra to treat heart failure in people who have had a heart attack.

Heart failure describes a condition in which your heart cannot pump enough blood to meet your body's needs. Heart failure sometimes develops after a heart attack due to damage to the heart muscles. Studies have shown that Inspra decreases the risk of dying when used for this purpose.

The FDA also approved Inspra to control high blood pressure (hypertension), particularly when other treatments have failed.

Inspra (Eplerenone) Drug Information: A person crossing their arms and a red circle on areas that are affected

Verywell / Zoe Hansen

How to Take Inspra

Inspra should be taken at the same time each day—once or twice daily, depending on your condition. Avoid grapefruit and grapefruit juice since grapefruit can raise Inspra levels and increase your risk of side effects. Also, be aware that potassium-containing salt substitutes can cause your potassium levels to become too high with Inspra.


Store Inspra at controlled room temperature (around 77 degrees Fahrenheit). Short trips out of the house in temperatures ranging from 59 to 86 degrees are permitted. Keep Inspra in a safe location that is high up and out of the reach of children and pets.

Off-Label Uses

Healthcare providers can prescribe medications off-label, meaning for conditions not approved by the FDA. Inspra is sometimes used off-label to treat heart failure in people who have not had a heart attack and for primary aldosteronism—a condition that occurs when your body produces too much aldosterone and causes high blood pressure.

How Long Does Inspra Take to Work?

Inspra begins to lower blood pressure within two weeks, but it can take four weeks to see the full effects. After four weeks, your healthcare provider may adjust your dose of Inspra depending on your blood pressure readings.

What Are the Side Effects of Inspra?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at or 800-FDA-1088.

Common Side Effects

Inspra is a well-tolerated medication, and most people don’t experience any side effects. The most common side effect of Inspra is an increase in potassium levels (hyperkalemia). Your healthcare provider will monitor your potassium levels before and during treatment with a blood test to ensure they don’t become too high.

Less common side effects include excess cholesterol and triglycerides in the blood.

Severe Side Effects

Rarely, Inspra may cause serious side effects. Call your healthcare provider right away if you develop any serious reactions. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency.

High Potassium Levels (Hyperkalemia)

Most people taking Inspra will only develop mild increases in their potassium levels. Rarely, Inspra may cause your potassium levels to become dangerously high. High potassium levels can lead to serious heart rhythm problems and be life-threatening. Call your healthcare provider right away if you experience any symptoms of high potassium, including:

  • Stomach pain, vomiting, or diarrhea 
  • Chest pain 
  • Confusion 
  • Feeling weak, lightheaded, or dizzy 
  • Irregular heartbeat 
  • Muscle weakness 
  • Numbness or tingling sensation 
  • Trouble breathing

Allergic Reaction

Some people may develop an allergic reaction to Inspra, which can be serious. Watch out for any signs of a reaction, including:

  • Hives 
  • Itching 
  • Rash 
  • Red, swollen, blistered, or peeling skin 
  • Swelling of the mouth, face, lips, tongue, or throat 
  • Tightness in the chest or throat 
  • Trouble breathing, swallowing, or talking 
  • Wheezing or unusual hoarseness

Report Side Effects

Inspra may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Inspra Should I Take?

Drug Content Provided by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):
    • For congestive heart failure after a heart attack:
      • Adults—At first, 25 milligrams (mg) once a day, then your dose may be increased to 50 mg once a day. Your doctor may adjust your dose as needed and tolerated.
      • Children—Use and dose must be determined by your doctor.
    • For high blood pressure:
      • Adults, teenagers, and children above 4 years of age—At first, 50 milligrams (mg) once a day. Your doctor may increase your dose to 50 mg two times a day.
      • Children up to 4 years of age—Use and dose must be determined by your doctor.


Healthcare providers generally do not recommend taking Inspra if you are pregnant or breastfeeding. Let your provider know if you’re pregnant or plan to become pregnant before starting Inspra.

Missed Dose

If you miss a dose of Inspra, take it as soon as you remember. If it’s almost time for your next dose, skip the missed dose and resume your regular dosing schedule. Don’t double up or take extra Inspra.

Overdose: What Happens If I Take Too Much Inspra?

While no cases of overdoses have been reported, taking too much Inspra would likely cause low blood pressure and increased potassium levels. Signs of an overdose may include:

  • Blurred vision 
  • Cold, gray skin 
  • Confusion 
  • Dizziness 
  • Fainting 
  • Irregular or slow heartbeat 
  • Lack of energy 
  • Muscle weakness 
  • Tingling in the arms and legs
  • Upset stomach

What Happens If I Overdose on Inspra?

If you think you or someone else may have overdosed on Inspra, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Inspra, call 911 immediately.


Drug Content Provided by IBM Micromedex®

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly and to decide if you should continue to take it. Blood tests may be needed to check for unwanted effects.

Do not take the following medicines if you are using eplerenone:

  • Amiloride (e.g., Midamor®) or
  • Clarithromycin (e.g., Biaxin®) or
  • Itraconazole (e.g., Sporanox®) or
  • Ketoconazole (e.g., Nizoral®) or
  • Nefazodone (e.g., Serzone®) or
  • Nelfinavir (e.g., Viracept®) or
  • Ritonavir (e.g., Norvir®) or
  • Spironolactone (e.g., Aldactone®) or
  • Triamterene (e.g., Dyrenium®) or
  • Troleandomycin (e.g., Tao®).

Do not take other medicines unless they have been discussed with your doctor. This especially includes potassium supplements or salt substitutes containing potassium.

This medicine may increase the amount of potassium in your blood. Check with your doctor right away if you are having abdominal or stomach pain; confusion; difficulty with breathing; irregular heartbeats; nausea or vomiting; nervousness; numbness or tingling in the hands, feet, or lips; shortness of breath; or weakness or heaviness of the legs.

What Are Reasons I Shouldn’t Take Inspra?

Certain conditions increase your risk of developing complications from Inspra. Your healthcare provider may treat you with a different medication if any of the following apply to you:

  • You have diabetes with protein in your urine.
  • You have high blood potassium levels.
  • You have severe kidney problems. 
  • You take certain medications that increase Inspra levels or increase potassium levels, such as Nizoral (ketoconazole), Sporanox (itraconazole), Serzone (nefazodone), Biaxin (clarithromycin), Kaletra (ritonavir), Viracept (nelfinavir), and potassium pills. 

What Other Medications Interact With Inspra?

Many drugs may interact with Inspra and cause adverse effects. Always keep an updated list of all the medicines you take and share this information with your healthcare providers and pharmacist any time there are changes.

Some medications can increase Inspra levels and should not be taken together. They include:

  • Biaxin or Biaxin XL (clarithromycin)
  • Crixivan (indinavir)
  • Invirase (saquinavir)
  • Lopinavir
  • Nizoral (ketoconazole)
  • Norvir (ritonavir)
  • Noxafil (posaconazole)
  • Onmel and Sporanox (itraconazole)
  • Prezista (darunavir)
  • Reyataz (atazanavir)
  • Serzone (nefazodone)
  • Tybost (cobicistat)
  • Vfend (voriconazole)
  • Viekira XR (ombitasvir, paritaprevir, ritonavir, dasabuvir) 
  • Viracept (nelfinavir)

Other medications can also increase Inspra levels. Your healthcare provider may recommend a lower dose of Inspra if you take any of the following:

  • Cardizem (diltiazem)
  • Erythromycin 
  • Diflucan (fluconazole)
  • Lexiva (fosamprenavir)
  • Multaq (dronedarone)
  • Verelan or Calan (verapamil)

Several drugs can increase the risk of developing high potassium levels with Inspra. Some of these medications are commonly taken with Inspra, such as angiotensin-converting enzyme (ACE) inhibitors. Your healthcare provider will closely monitor your potassium levels. Other medications, such as Gengraf (cyclosporine), should also be avoided.

Be cautious when taking the following medications with Inspra:

  • ACE inhibitors, such as Qbrelis (lisinopril), Vasotec (enalapril), and Lotensin (benazepril)
  • Aldactone (spironolactone)
  • Angiotensin receptor blockers (ARBs) like Entresto (valsartan), Benicar (olmesartan), or Cozaar (losartan)
  • Bactrim (sulfamethoxazole/trimethoprim) 
  • Dyazide (triamterene)
  • Gengraf (cyclosporine) 
  • Macrobid (nitrofurantoin
  • Midamor (amiloride)
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) like Advil or Motrin (ibuprofen) or Aleve (naproxen) 
  • Potassium supplements 
  • Primsol (trimethoprim)

This is not a complete list of all the medications that may interact with Inspra. Always talk to your healthcare provider or pharmacist before starting anything new.

What Medications Are Similar?

Aldactone (spironolactone) is another potassium-sparing diuretic that blocks aldosterone. It is also used to treat heart failure and high blood pressure. When choosing between Aldactone and Inspra, most healthcare providers will prescribe Aldactone first since it’s less expensive. But some people aren’t able to tolerate Aldactone.

Unlike Inspra, Aldactone causes several unpleasant side effects, including gynecomastia (enlarged breast tissue in men) and sexual dysfunction. Inspra is often prescribed for people who are unable or unwilling to take Aldactone due to its side effects.

Frequently Asked Questions

  • What is Inspra used for?

    Inspra is used to treat heart failure in people that have had a heart attack. It can also be used to treat high blood pressure, often when other medications haven’t worked.

  • How does Inspra work?

    Inspra works by blocking the effects of aldosterone—a naturally occurring substance in your body that raises blood pressure and causes you to retain fluid. Inspra is considered a potassium-sparing diuretic, which means it removes excess fluid from your body without removing potassium. This is why some people may develop high blood potassium levels while taking Inspra.

  • How long does it take Inspra to work?

    It will take four weeks for you to see the full effects of Inspra. After that time, your healthcare provider may decide to adjust your dose depending on your symptoms.

  • What are the side effects of Inspra?

    The most common side effect of Inspra is high blood potassium levels (hyperkalemia). Your healthcare provider will check your potassium levels before you start Inspra and then periodically during treatment to ensure they don’t become too high.

How Can I Stay Healthy While Taking Inspra?

Having a condition that affects your heart can be scary—especially if you’ve had a heart attack. Luckily, exercise, diet changes, and medications can all help improve your outcomes. Your healthcare provider may prescribe Inspra as one part of your treatment plan.

Most people tolerate Inspra without any issues, but be sure to regularly follow up with any blood tests your doctor has ordered to ensure you can continue using Inspra safely. Don’t hesitate to let your healthcare team know about all your concerns. Together you will develop a plan that keeps you and your heart healthy.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Inspra label.

  2. Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on clinical practice guidelines. Hypertension. 2018;71(6):e13-e115. doi:10.1161/HYP.0000000000000065

  3. ​​Bailey DG, Dresser G, Arnold JM. Grapefruit-medication interactions: forbidden fruit or avoidable consequences?. CMAJ. 2013;185(4):309-316. doi:10.1503/cmaj.120951

  4. Drugs and Lactation Database (LactMed). Eplerenone

  5. MedlinePlus. Eplerenone.

  6. Prescribers' Digital Reference. eplerenone - Drug Summary.

By Christina Varvatsis, PharmD
Christina Varvatsis is a hospital pharmacist and freelance medical writer. She is passionate about helping individuals make informed healthcare choices by understanding the benefits and risks of their treatment options.