Amitiza (lubiprostone) is a brand-name drug that’s prescribed for certain types of constipation in adults. Amitiza comes as an oral capsule that’s typically taken twice per day. The dosage can vary depending on the condition being treated.

Amitiza belongs to a drug class called chloride channel activators. Amitiza is available in a generic version.

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

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

The information below describes typical Amitiza dosages for treating certain types of constipation in adults.

Amitiza form

Amitiza comes as an oral capsule.

Amitiza strengths

Amitiza comes in two strengths:

  • 8 micrograms (mcg)
  • 24 mcg

Typical dosages

The following information describes dosages that are commonly prescribed or recommended. 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 chronic idiopathic constipation and opioid-induced constipation

Amitiza is used in adults to treat chronic idiopathic constipation (ongoing constipation that doesn’t respond well enough to laxatives). It’s also used to treat opioid-induced constipation in adults. The typical Amitiza dosage for these conditions is 24 mcg twice per day.

Dosage for irritable bowel syndrome with constipation

Amitiza is used to treat irritable bowel syndrome with constipation in adult females.* The typical Amitiza dosage for this condition is 8 mcg twice per day.

* Sex and gender exist on spectrums. Use of the term “female” in this article refers to sex assigned at birth.

Long-term treatment

Amitiza is meant to be taken as a long-term treatment. If you and your doctor determine that Amitiza is safe and effective for you, you’ll likely take it long term.

Talk with your doctor if you have questions about your Amitiza dosage.

The Amitiza dosage your doctor prescribes will depend on several factors. These include:

  • the type of constipation you’re taking Amitiza to treat
  • how well your liver works
  • whether you have other medical conditions

Dosage adjustments

If you have certain liver problems, your doctor may prescribe a lower dosage of Amitiza. So if you have a history of liver problems, let your doctor know. They’ll determine the right dosage for you. Before starting treatment, your doctor may check your liver function.

If you have questions about dosage adjustments for Amitiza, talk with your doctor.

Amitiza comes as an oral capsule that you’ll swallow whole with water. Be sure to take it with food.

Typically, you’ll take Amitiza twice per day. It may be helpful to take Amitiza at around the same time each day, such as morning and evening. This helps maintain a steady level of the drug in your body so Amitiza can work effectively.

When taking Amitiza, do not open the capsule or chew on it.

If you have trouble swallowing capsules, see this article for tips on how to take this form of medication. You can also 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 about putting Amitiza in an easy-open container. They also may recommend tools that can make it easier to open bottles.

If you miss a dose of Amitiza, take it as soon as you remember. However, if it’s almost time for your next dose, skip the missed dose. Then, take your next scheduled dose. You should not take two doses to make up for the missed one. If you’re unsure whether to take or skip a missed dose, talk with your doctor or pharmacist.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm or putting a note where you’ll see it, such as on your bathroom mirror or bedside table. You could also download a reminder app on your phone.

If you take more Amitiza than your doctor prescribes, you may develop serious side effects. To learn about side effects of Amitiza, see this article.

It’s important that you do not take more Amitiza than your doctor advises.

Symptoms of an overdose

Amitiza overdose symptoms can include:

If you take more than the recommended amount of Amitiza

Call your doctor right away if you believe you’ve taken too much Amitiza. 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.

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

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

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

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.