Lopressor (metoprolol tartrate) is a prescription drug that’s used to treat certain heart-related conditions. The drug comes as a tablet you swallow. It’s usually taken once or twice per day.

Lopressor is used in adults to:

The active ingredient in Lopressor is metoprolol tartrate. (An active ingredient is what makes a drug work.) Lopressor belongs to a group of drugs called beta-blockers.

This article describes the dosages of Lopressor, as well as its strengths and how to take it. To learn more about Lopressor, see this in-depth article.

The table below highlights the basics of Lopressor’s dosage. All doses are listed in milligrams (mg).

ConditionStarting dosageMaintenance dosageMaximum dosage
high blood pressure100 mg daily in one or two divided doses100–450 mg daily450 mg daily
angina50 mg twice per day100–400 mg daily400 mg daily
heart attack (late treatment)100 mg twice per day100 mg twice per day for at least 3 months100 mg twice per day for 3 months or longer

Keep reading for more details about Lopressor’s dosage.

What’s the form of Lopressor?

Lopressor comes as a tablet you take by mouth.

What strengths does Lopressor come in?

Lopressor is available in two strengths: 50 mg and 100 mg.

What are the usual dosages of Lopressor?

The dosage of Lopressor you’re prescribed depends on your condition and how severe it is, your age, and other factors.

Your doctor will likely start you on the recommended dosage for your particular condition. Then they’ll likely adjust it over time to reach the right amount for you. They’ll ultimately prescribe the smallest dosage that provides the desired effect.

The information below describes dosages that are commonly used or recommended. But be sure to take the dosage your doctor prescribes for you. They’ll determine the best dosage to fit your needs.

Dosage for hypertension (high blood pressure)

Your Lopressor dosage for treating hypertension depends on the severity of your condition and other individual factors, such as other medications you’re taking.

The starting dosage is typically 100 mg daily. This can be taken as one dose or in two equally divided doses, one in the morning and one in the evening.

Your doctor will see how you respond to treatment and adjust your dose accordingly. This is usually done on a weekly basis.

Your maintenance dosage can range from 100–450 mg per day. Ultimately, your doctor will prescribe the lowest dose that manages your condition.

The maximum dosage of Lopressor for hypertension is 450 mg per day.

If you have questions about your dosage of Lopressor, talk with your doctor.

Dosage for chest pain

The usual starting dose of Lopressor for angina (chest pain) is 100 mg daily. This is generally taken as 50 mg twice per day (in the morning and evening).

Your doctor will monitor how you respond to Lopressor and adjust your dosage weekly until your condition is managed. The typical maintenance dosage ranges from 100–400 mg per day.­­

The maximum dosage of Lopressor for angina is 400 mg per day.

If you need to stop taking Lopressor, your doctor will gradually lower your dosage over 1–2 weeks to reduce your risk of side effects.

Dosage for reducing risk of death in people who have had a known or possible heart attack

If you’ve had (or are suspected of having had) a heart attack, Lopressor is usually given as an intravenous (IV) injection (into a vein) in the hospital at first. After this, you’ll be switched to Lopressor oral tablets.

Your starting dosage depends on several factors. These include:

  • the severity of your condition
  • how well your body handles the Lopressor IV dose
  • your age
  • if you have liver problems

You’ll initially be given three doses of 5 mg of Lopressor via an IV in the hospital. If your body responds well to the full 15-mg dose, your doctor will switch you to a 50-mg Lopressor oral tablet taken every 6 hours.

You’ll take the first dose of oral Lopressor tablet 15 minutes after your last Lopressor IV dose. This dose will typically continue for 48 hours.

The maintenance dosage of Lopressor oral tablets is 100 mg taken twice per day. But if you’re unable to tolerate the full 15-mg Lopressor IV dose, your doctor may start you on 25 mg or 50 mg of Lopressor tablets. You’ll take a dose every 6 hours, beginning 15 minutes after your last Lopressor IV dose and depending on your response to the dose of Lopressor.

You’ll typically take Lopressor 100 mg twice daily for 3 months or longer. Your doctor will discuss how long your treatment is likely to last.

Is Lopressor taken long term?

Whether you take Lopressor long term depends on the condition you’re taking the drug to treat and your response to it. Doctors usually prescribe Lopressor long term for high blood pressure and angina. If you and your doctor determine it’s safe and effective for your condition, you’ll likely take the drug long term.

Lopressor is typically taken for at least 3 months to lower the risk of death in people who’ve had a known or possible heart attack. Your doctor may recommend taking the drug for up to 1–3 years based on how you respond to it.

Dosage adjustments

In some cases, you may need a dosage adjustment for Lopressor. For example, your doctor may start you on a lower dosage if you have liver problems. This is because your liver removes Lopressor from your body. But if you have liver problems, the drug could build up, increasing your risk of side effects.

Tell your doctor if you have liver problems. They’ll determine the Lopressor dosage that’s right for you.

Below are answers to some commonly asked questions about Lopressor’s dosage.

Is Lopressor available as an IV? Is the dosage of the IV form similar to that of the oral tablet?

Yes. Lopressor is available as an intravenous (IV) injection (into a vein). This is typically given by a healthcare professional in a hospital if you’ve had a known or suspected heart attack. The dosage depends on the severity of your condition and your response to treatment.

The dosage of the Lopressor IV is different from the dosage of Lopressor tablets. The IV dosage is typically 5 mg given every 2 minutes for three doses.

After 15 minutes, you’ll be switched to oral Lopressor tablets. If you tolerate the three IV doses, you’ll take a 50-mg tablet every 6 hours for 48 hours. Then you’ll be on a maintenance dosage of 100 mg twice per day for 3 months or longer based on your doctor’s guidance.

Your dosage for the Lopressor IV dose or oral tablets depends on how you respond to the medication. Your doctor can provide more information about how the two forms of the drugs differ.

Can Lopressor be used for AFib? If so, what’s the dosage?

Yes, it’s possible. Lopressor is not approved for atrial fibrillation (AFib), but your doctor may prescribe the drug off-label for this purpose. (With off-label use, a drug is prescribed for a condition it’s not approved to treat.)

AFib refers to an irregular heartbeat which can interrupt the usual flow of blood and increase your risk of having a stroke or blood clots. Symptoms include:

A 2017 study showed that metoprolol (the active ingredient* in Lopressor) is effective for treating AFib.

If you have questions about taking Lopressor for AFib and its dosage, talk with your doctor. They can provide more information about the benefits and risks of Lopressor for this condition.

* An active ingredient is what makes a drug work.

The dosage of Lopressor you’re prescribed may depend on several factors. These include:

  • the type and severity of the condition you’re taking the drug to treat
  • your age
  • other conditions you may have (see the “Dosage adjustments” section above)

Lopressor comes as an oral tablet. You can take it with food or immediately after a meal. Do not crush or chew Lopressor tablets. This may alter your dosage.

However, if your doctor prescribes a dose that’s not available (Lopressor comes in 50-mg and 100-mg strength tablets), they may suggest you cut your tablets to get your exact dose. For example, if your dose is 25 mg, you would cut the 50-mg tablet exactly in half for your dose. Your pharmacist can show you how to cut the tablet if needed.

You’ll typically take Lopressor tablets once or twice per day. Twice daily doses can be taken in the morning and evening.

If you have trouble swallowing tablets, see this article for tips on how to take this form of medication.

For information on the expiration, storage, and disposal of Lopressor, see this article.

Accessible drug containers and labels

Some pharmacies provide medication labels that:

  • have large print
  • use braille
  • feature a code you can scan with a smartphone to change the text to audio

Your doctor or pharmacist may be able to recommend pharmacies that offer these accessibility features if your current pharmacy doesn’t.

If you have trouble opening medication bottles, let your pharmacist know. They may have tips to help make it simpler. Or they may be able to supply Lopressor in an easy-open container.

If you miss your scheduled dose of Lopressor, take it as soon as you remember. But if it’s close to the time for your next dose, skip the missed dose and continue with your dosing schedule. Do not take two doses of Lopressor at once, as this could increase your risk of serious side effects. Ask your doctor or pharmacist if you’re unsure about taking a missed dose.

If you need help remembering to take your dose of Lopressor on time, try using a medication reminder. This can include setting an alarm or downloading a reminder app on your phone.

Do not take more Lopressor than your doctor prescribes, as this can lead to serious side effects.

Symptoms of overdose

Symptoms caused by an overdose can include:

In extreme cases, an overdose of Lopressor could lead to coma or death.

What to do in case you take too much Lopressor

Call your doctor right away if you think you’ve taken too much Lopressor. You can also call 800-222-1222 to reach America’s Poison Centers or use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

The sections above describe the usual dosages provided by the drug manufacturer. If your doctor recommends Lopressor, they’ll prescribe the dosage that’s right for you.

Remember, you should not change your dosage of Lopressor without your doctor’s recommendation. Only take Lopressor exactly as prescribed. Talk with your doctor if you have questions or concerns about your current dosage. Here are some examples of questions you may want to ask:

  • How long will it take for my dosage of Lopressor to work?
  • Will I need a lower dosage of Lopressor if I’m taking other medications for my condition?
  • Would I have a higher risk of side effects if I take the maximum dose of Lopressor?

To learn more about Lopressor, see these articles:

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Disclaimer: Healthline 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.