Zestril (lisinopril) is a brand-name drug prescribed for high blood pressure in adults and some children, as well as for certain heart conditions in adults. Zestril comes as an oral tablet that’s typically taken once per day.

Zestril is approved by the Food and Drug Administration (FDA) to:

Zestril belongs to the drug class called angiotensin converting enzyme (ACE) inhibitors. Zestril is available in a generic version.

Keep reading for specific information about the dosage of Zestril, including its strengths and how to take the medication. For a comprehensive look at Zestril, see this article.

Note: This article describes typical dosages for Zestril provided by the drug’s manufacturer. When taking Zestril, always follow the dosage prescribed by your doctor.

Below is information about Zestril’s form, strengths, and dosages for its approved uses.

Zestril form

Zestril comes as an oral tablet.

Zestril strengths

Zestril comes in six different strengths:

  • 2.5 mg (milligrams)
  • 5 mg
  • 10 mg
  • 20 mg
  • 30 mg
  • 40 mg

Typical dosages

Typically, your doctor will start by prescribing you a low dosage. Over time, they’ll adjust it to reach the amount that’s right for you. Your doctor will usually prescribe the smallest dosage that provides the desired effect.

The following information describes dosages commonly prescribed in adults. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Dosage for high blood pressure

Doctors may prescribe Zestril to treat hypertension (high blood pressure). For this use, it may be prescribed in combination with other blood pressure medications, such as diuretics. The starting dose may vary depending on whether it’s prescribed alone, or with other medications.

Dosage for high blood pressure when used alone: If Zestril is prescribed alone, your starting dose will likely be 10 mg. Typically, you’ll take this once per day. Depending on how your blood pressure responds, your doctor may increase your dosage. The usual dosage range for high blood pressure is 20–40 mg, taken once per day.

If this dose isn’t managing your blood pressure, your doctor may adjust the dosage up to 80 mg per day. This is also the maximum recommended daily dose of Zestril for high blood pressure.

Dosage for high blood pressure when used with other drugs: If you’re already taking a diuretic, the recommended starting dosage of Zestril is 5 mg once per day. If your doctor prescribes Zestril first and then adds a diuretic, they may then be able to lower your Zestril dosage.

If you take other blood pressure medications (that aren’t diuretics) with Zestril, your doctor will likely tailor your dosage. Your specific dosage will depend on your blood pressure readings before and after treatment. Zestril’s usual dosage range for high blood pressure is 20–40 mg, taken once per day.

Talk with your doctor if you have questions about your dosage for high blood pressure.

Dosage for heart failure

Zestril is also approved as an add-on medication to help treat heart failure. “Add-on” means you’ll take it with other heart failure drugs. In this case, the recommended starting dose of Zestril is 5 mg. You’ll usually take it once per day. For heart failure, the dosage can be increased to a maximum recommended dosage of 40 mg once per day.

Dosages for heart failure may vary based on a person’s lab results and how their doctor is monitoring them. See the “Factors that can affect your dosage” section below for details.

Talk with your doctor if you have questions about your dosage for heart failure.

Dosage for heart attack

Zestril is also prescribed to decrease the risk of death after a person has had a heart attack. Zestril is started immediately following the heart attack, often while you’re still in the hospital.

For most people, the recommended starting dose of Zestril after a heart attack is 5 mg. You’ll usually take this once within the first 24 hours after your heart attack. Then 24 hours after your first dose, your doctor will give you a second 5-mg dose. After 48 hours, they’ll increase the dose to 10 mg. Typically, you’ll take 10 mg once per day for at least 6 weeks.

Talk with your doctor if you have questions about your dosage for heart attack.

Children’s dosage

Zestril is approved to treat high blood pressure in children ages 6 years and older. The dosage is based on the child’s body weight in kilograms (kg).* The dosage per kg is measured in milligrams per kilogram (mg/kg) and is calculated by your child’s doctor.

Zestril’s typically recommended starting dose for children is 0.07 mg/kg of body weight, up to 5 mg, once per day. For example, the starting dose for a child who weighs 99 pounds (lb), which is about 45 kg, would be 3.15 mg per day.

Your child’s doctor will adjust their dose as needed. The maximum amount the dose can be adjusted to is 0.61 mg/kg, up to 40 mg in total, once per day.

Your child’s doctor will determine the dosage that’s right for your child. If you have questions about this, talk with their doctor.

* One kg equals about 2.2 pounds (lb).

Long-term treatment

Zestril is meant to be a long-term treatment in most cases. If you and your doctor determine that Zestril is safe and effective for you, you’ll likely take it long term.

If you’re taking Zestril following a heart attack, it’s usually prescribed for at least 6 weeks.

Prior to you taking Zestril, your doctor will discuss the expected course of treatment with you. Talk with your doctor if you have questions about how long you can expect to take Zestril.

The Zestril dosage your doctor prescribes will depend on several factors, which may include:

  • in children, their weight and age
  • the type and severity of the condition you’re taking Zestril for
  • your kidney function and whether you receive dialysis
  • your lab results, including sodium, potassium, and fluid levels
  • your blood pressure readings
  • how your body and condition respond to Zestril
  • other medications you take
  • side effects you may have with Zestril

Other medical conditions you have can also affect your Zestril dosage.

Dosage adjustments

Your doctor will determine whether dose adjustments are necessary. For example, they may lower your starting dose for heart failure if you have low sodium levels. They may also lower it after a heart attack if you have low blood pressure.

If you have kidney disease or you’re undergoing hemodialysis (a certain type of dialysis), your doctor may adjust your dosage.

Your doctor may need to adjust your dosage if you take certain medications. These include diuretics or other blood pressure medications. Taking these drugs and Zestril can lower your blood pressure more than if you were taking Zestril alone. If your blood pressure gets too low, your doctor may need to change your dose of Zestril, the other medication, or both. If you experience symptoms, such as dizziness, lightheadedness, or fainting, tell your doctor. They may want to make dosage changes.

To help monitor Zestril’s effects, your doctor may schedule follow-up visits and blood tests. Try to keep these appointments. Your doctor can tell you more about what lab tests you’ll need. Also, be sure to tell your doctor about all medications you take and any health conditions you may have. This will help them prescribe a safe and suitable dosage for your condition.

Zestril comes as a tablet that you swallow. The tablets may be crushed for use in an oral liquid suspension that you swallow. Your pharmacist can prepare the suspension for you. If needed, the tablets can also be split in half and swallowed.

While Zestril can be cut, not all tablets should be. Check with your pharmacist before cutting your medication. If you have trouble swallowing tablets whole, talk with your doctor or pharmacist. They can help you find solutions that work for your situation.

You may take your dose of Zestril with or without food. It can be taken at any time throughout the day, but it’s best to take Zestril at the same time each day. This helps maintain a steady level of Zestril in your body so it can work effectively.

You should take Zestril as instructed by your doctor. If you have questions about how to take Zestril, talk with your doctor or pharmacist.


Some pharmacies offer labels with large print, braille, or a code you scan with a smartphone to convert text to speech. If your local pharmacy doesn’t have these options, your doctor or pharmacist might be able to recommend a pharmacy that does.

If you’re having trouble opening medication bottles, ask your pharmacist to put Zestril in an easy-open container. They also may recommend tools that can make it easier to open bottles.

The prescribing information for Zestril doesn’t specifically state what to do if you miss a dose. If you do miss a dose of Zestril, call your doctor or pharmacist for advice. If the dose you missed was recent, they may tell you to take it as soon as you remember. If it’s almost time for your next dose, they’ll likely suggest that you skip the missed dose and take your next scheduled dose at the regular time.

Do not “double-up” or take two doses at once to make up for a missed dose. Doing so could increase your risk of dangerously low blood pressure or side effects.* If you’re not sure whether you should take a missed dose or skip it, check with your doctor or pharmacist.

To help ensure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm or leaving a note where you’ll see it, such as on your kitchen counter, bathroom mirror, or bedside table. Downloading a reminder app for your phone is also an option.

* For details about this, see the “Side effects” section of this article.

It’s important that you do not take more Zestril than your doctor prescribes. Taking too much Zestril can lead to harmful effects.

Symptoms of an overdose

Overdose symptoms of Zestril can include low blood pressure. If you develop low blood pressure you may feel:

If you take more than the recommended amount of Zestril

Call your doctor right away if you believe you’ve taken too much Zestril. Another option is to call America’s Poison Centers at 800-222-1222 or use its online tool. If you have severe symptoms, immediately call 911 or your local emergency number or go to the nearest emergency room.

Below are the answers to some frequently asked questions about Zestril.

What’s the recommended maximum dosage of Zestril?

The recommended maximum dosage of Zestril in adults is 80 mg per day for high blood pressure and 40 mg per day for heart failure. For children, the maximum dosage of Zestril that’s recommended is 40 mg per day.

Typically, doctors prescribe a low dosage to start and increase the drug’s dosage from there. The recommended starting and maximum doses may differ based on the condition Zestril is treating and other factors. For example, doctors usually won’t prescribe more than the maximum recommended dose of 40 mg per day for any condition in people with kidney disease. For more information, see the “Zestril dosage” and “Factors that can affect your dosage” sections above.

If you have questions or concerns about your dosage of Zestril, talk with your doctor or pharmacist. If it seems like you need an adjustment to your dosage, ask your doctor whether a different dosage is right for you. Do not increase your dosage unless your doctor advises you to.

Is 20 mg considered a high dose of Zestril?

Generally, no. A Zestril dose of 20 mg would be considered a standard maintenance dose for high blood pressure or heart failure. Typically, doctors start Zestril treatment at a low dose (the starting dose). Then they increase it over time until they reach a dose that best treats the condition (the maintenance dose).

However, for treatment after a heart attack, 20 mg per day would be considered a high dose of Zestril. For this use, the typically recommended maintenance dose is 10 mg per day. For details, see the “Zestril dosage” section above.

If you have concerns about your Zestril dosage, talk with your doctor or pharmacist. Do not change your dosage unless your doctor advises you to.

The dosages in this article are typical dosages provided by the drug’s manufacturer. If your doctor recommends Zestril for you, they’ll prescribe the dosage that’s right for you. Always follow the dosage that your doctor prescribes.

If you feel that Zestril isn’t working for your condition or situation, talk with your doctor. They may be able to find a solution or recommend different treatment options.

As with any drug, never change your dosage of Zestril without your doctor’s recommendation. If you have questions about the dosage of Zestril that’s best for you, talk with your doctor.

Besides learning about dosage, you may want other information about Zestril. These additional articles might be helpful:

  • More about Zestril: For information about other aspects of Zestril, refer to this article.
  • Details about your condition: For details about some of the conditions Zestril is prescribed to treat, see our hypertension and cardiovascular health hubs.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.