Mestinon (pyridostigmine) is a prescription drug that’s used to treat myasthenia gravis. The drug comes as a liquid solution, tablet, and extended-release tablet. Your dosage depends on the form you’re prescribed and the severity of your condition.

Mestinon is approved to treat myasthenia gravis in adults.

The active ingredient in Mestinon is pyridostigmine. (An active ingredient is what makes a drug work.) It’s a monoclonal antibody and belongs to a group of drugs called cholinesterase inhibitors.

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

This section describes the usual dosages of Mestinon. Keep reading to learn more.

What are Mestinon’s forms?

Mestinon comes in three oral forms:

  • liquid solution
  • tablet
  • extended-release (ER) tablet

The liquid solution and tablets are immediate-release (IR) drugs. This means that they release the drug into your body right away. On the other hand, ER tablets slowly release the drug into your body over a long period of time.

What strengths does Mestinon come in?

Mestinon comes in different strengths depending on its form:

  • liquid solution: 60 milligrams per 5 milliliters of solution (60mg/5mL)
  • tablet: 60 mg
  • ER tablet: 180 mg

What are the usual dosages of Mestinon?

Your doctor will likely start you on a low dosage and 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 myasthenia gravis

For treatment of myasthenia gravis, your doctor may recommend that you combine different Mestinon forms. For example, they may suggest that you take the liquid solution in the morning when swallowing is more difficult and then switch to the tablets later in the day once the medication has started to work. They may also recommend a combination of IR and ER forms to manage your symptoms more effectively.

IR tablet and liquid solution. IR forms release the drug into your body soon after taking them. A typical starting dosage of IR Mestinon is 60–360 mg per day. This dosage will be divided into smaller doses to be taken throughout the day.

Depending on how you respond to the medication and your symptom severity, your doctor may prescribe a higher Mestinon dosage. On average, adults with myasthenia gravis take 600 mg of IR Mestinon in divided doses throughout the day.

ER tablet. ER forms release the drug into your body more slowly and over a longer period of time. Each Mestinon ER tablet is 180 mg. If you’re prescribed the Mestinon ER tablets, the typical dosage is one to three tablets (180–540 mg) once or twice per day. If you’re taking two doses per day, each dose should be separated by at least 6 hours.

The maximum dosage of Mestinon is 1,500 mg per day. The maximum dosage is for all forms of Mestinon combined.

If you have questions about your dosage and dosing schedule, talk with your doctor or pharmacist.

Is Mestinon used long term?

Yes, Mestinon is usually used as a long-term treatment. If you and your doctor determine that it’s safe and effective for your condition, you’ll likely take it long term.

Dosage adjustments

Mestinon is primarily removed from your body by your kidneys. If you have kidney disease, your doctor may lower your dosage.

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

  • the severity of your myasthenia gravis symptoms
  • the form of Mestinon you’re taking
  • other conditions you may have (see the “Dosage adjustments” section above)

All forms of Mestinon are swallowed. They can be taken with or without food. But taking Mestinon with food may decrease the risk of certain side effects, such as nausea and abdominal cramps.

Mestinon IR and ER tablets can likely be split. They have one or two lines dividing the tablet into sections, which makes them easier to split. But the drug manufacturer hasn’t provided information about whether Mestinon should be split, chewed, or crushed. Talk with your doctor if you have questions about splitting, chewing, or crushing Mestinon tablets.

If you have trouble swallowing tablets, talk with your doctor about the liquid solution form. You can also read this article for tips on taking tablets.

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.

Let your pharmacist know if you have trouble opening medication bottles. They may have tips to help, or they may be able to supply Mestinon in an easy-open container.

If you miss a dose of Mestinon, talk with your doctor.

Your Mestinon dosing schedule is personalized for you. Your treatment plan may include both immediate-release and extended-release forms that release the drug into your body at different times. This makes missing a dose more complicated. That’s why it’s important to talk with your doctor if you miss a dose.

If you need help remembering to take your dose of Mestinon 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 Mestinon than your doctor prescribes, as this can lead to harmful effects.

Symptoms of overdose

An overdose of Mestinon may cause a cholinergic crisis. This is a serious condition that can lead to death. Symptoms of a cholinergic crisis include:

What to do in case you take too much Mestinon

Call your doctor right away if you think you’ve taken too much Mestinon. 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.

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

Is Mestinon’s dosage similar to the dosages of Rituxan?

No, the dosages of the two drugs aren’t similar. Mestinon and Rituxan (rituximab) come in different forms and have different dosing schedules.

Mestinon comes in forms that you swallow. It’s taken several times per day.

Rituxan comes as a liquid solution that’s given as an intravenous (IV) infusion (an injection into a vein given over time). It’s given by a healthcare professional in a doctor’s office or clinic. The dosing schedule for Rituxan depends on the condition it’s being used to treat.

You can see this article for more information about Rituxan’s dosages, but the article doesn’t describe the dosing schedule for myasthenia gravis. This is because myasthenia gravis is an off-label use* of Rituxan. Drug manufacturers don’t provide dosage information for off-label uses. Studies of Rituxan have shown it to be a safe and effective treatment for myasthenia gravis, so talk with your doctor if you’d like to learn more about Rituxan.

* An off-label use is when a medication is used for a purpose other than for what it was originally approved for.

How long does it take for Mestinon to start working?

Immediate-release forms of Mestinon start to work within 15–30 minutes after you take a dose. But it may take a couple of weeks for you and your doctor to determine the best treatment regimen for you.

If you have questions about what to expect from your Mestinon treatment, talk with your doctor.

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

Remember, you should not change your dosage of Mestinon without your doctor’s recommendation. Only take Mestinon 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 your doctor:

  • Does my risk of side effects increase with a higher dosage of Mestinon?
  • Do different forms of Mestinon have different costs?
  • How does the dosage of Mestinon compare with the dosage of CellCept (mycophenolate mofetil)?

To learn more about Mestinon, 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.