Amitiza (lubiprostone) is a prescription drug used to treat certain forms of constipation in adults. The drug comes as an oral capsule and is usually taken twice per day.

Specifically, Amitiza is prescribed to treat:

The active ingredient in Amitiza is lubiprostone. Amitiza belongs to a group of drugs called chloride channel activators.

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

* Note: In this article, we use the term “female” to refer to someone’s sex assigned at birth. To learn more about the difference between sex and gender, see this article.

This section describes the usual dosages of Amitiza.

What is Amitiza’s form?

Amitiza comes as a capsule you swallow.

What strengths does Amitiza come in?

Amitiza is available in two strengths: 8 micrograms (mcg) and 24 mcg.

What are the usual dosages of Amitiza?

Amitiza’s dosages (including its starting dose and maximum dosage) depend on several factors, including the condition it’s being used to treat.

The information below describes dosages that are commonly used or recommended. But be sure to take the dosage your doctor prescribes. They’ll determine the best dosage to fit your needs, which in some cases may be different from those shown below.

Dosage for CIC and OIC

The typical Amitiza dosage for both CIC and OIC is 24 mcg, taken twice per day. However, in some cases, your doctor may adjust your dosage.

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

Dosage for IBS-C

The typical dosage of Amitiza for IBS-C in adult females is 8 mcg taken twice per day. However, in some cases, your doctor may adjust your dosage.

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

How to take Amitiza

Amitiza comes as an oral capsule you take with food and a full glass of water, usually twice per day. You should try to take it around the same times each day. Do not crush, chew, or cut Amitiza capsules. This can affect how the medication works.

If you have trouble swallowing capsules, see this article for some helpful tips. You can also talk with your pharmacist to discuss options.

Is Amitiza used long term?

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

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

How long does it take for Amitiza to work?

In studies, most people had a bowel movement within 24 to 48 hours of taking Amitiza. Because of how the drug works, you likely won’t feel it working in your body. Your doctor will monitor you during treatment to be sure the drug is effectively treating your condition.

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

Does Amitiza cause weight loss?

It’s unlikely. However, diarrhea was a common side effect of Amitiza in the drug’s studies. In rare cases, severe diarrhea is possible which may cause some temporary weight loss.

If you experience severe diarrhea, stop taking Amitiza and call your doctor right away. They’ll likely suggest other, safer options to treat your condition. If you have questions about weight changes with Amitiza, talk with your doctor or pharmacist.

Do not take more Amitiza than your doctor prescribes, as this can lead to harmful effects.

Symptoms of overdose

Symptoms caused by an overdose can include:

What to do in case you take too much Amitiza

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

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.