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Amitiza is a prescription medication that is approved to treat IBS-C in women 18 years of age and older. For the treatment of IBS-C, Amitiza is given in an 8 mcg capsule twice daily. Amitiza has been proven to help address the overall symptoms of IBS-C, including abdominal discomfort, abdominal pain, bowel habits and other IBS symptoms.1

Different than fiber or laxatives, Amitiza is called a CIC-2 chloride channel activator. While the mechanism of action isn’t fully known, Amitiza works locally in the intestinal tract to promote fluid secretion by targeting the chloride channels. The increased fluid in the intestines increases the motility, which helps move the stool through and alleviates constipation.1

The U.S. Food and Drug Administration approved Amitiza in 2008, and it was the first prescription drug therapy for IBS-C.2

Taking Amitiza

Amitiza is taken twice daily in a capsule form. The capsule should be swallowed whole and can be taken with food and water. If a dose is missed, that dose should be skipped and continue with the next dose at the next regular time. Patients should not take two doses at the same time.1

Amitiza should be stored at room temperature in a closed, child-proof container. Amitiza may affect how other medications work, just as other medications could affect how Amitiza works. Patients should discuss all medications they use with their doctor to determine if Amitiza is the right option for them.1

Who shouldn’t take Amitiza

Amitiza should not be taken if the patient has a known or suspected blockage in their bowel or if the patient is experiencing severe diarrhea. If the patient is pregnant or becomes pregnant, she should discuss with her doctor the risks of Amitiza causing harm to the fetus. Women who are breastfeeding should tell their doctor and monitor infants for diarrhea. Amitiza should not be taken by patients who are allergic to Amitiza or any of its ingredients, including lubiprostone. The 8 mcg (pink) capsules also contain the dyes ferric oxide and titanium dioxide.1

Possible side effects when taking Amitiza

The most common side effects experienced while taking Amitiza for IBS-C are headache, nausea, diarrhea and abdominal pain. Other rare side effects include urinary tract infections, dry mouth, fainting, peripheral edema (swelling of the extremities), difficulty breathing and heart palpitations. Patients who experience these or other side effects are encouraged to talk to their doctor.1,2

Additional treatment options for IBS

Because of the individuality of each patient, not all patients respond the same to each treatment. There are a number of treatment options for IBS, and most patients find a combination of approaches work best for managing their symptoms. In addition to medication, other treatment strategies include diet changes, probiotics, stress management, exercise and alternative therapies.

Written by: Emily Downward | Last reviewed: July 2019
  1. Amitiza product website, Sucampo AG, Takeda Pharmaceuticals. Accessed online on 3/8/16 at
  2. FDA approves Amitiza for IBS-C. Food and Drug Administration. Accessed online on 3/9/16 at