What You Should Know About Amitiza Side Effects

Starting a new medication always comes with questions — and concerns about side effects are usually at the top of the list. If your doctor has prescribed Amitiza (Lubiprostone) for chronic constipation, IBS-C, or opioid-induced constipation, here's what you need to know about potential side effects, how to manage them, and when to seek medical help.

What Is Amitiza?

Amitiza is a prescription medication that contains Lubiprostone, a chloride channel activator. It works by increasing fluid secretion in your intestines, which softens stool and promotes natural bowel movements. It's FDA-approved for three conditions:

• Chronic idiopathic constipation (CIC) in adults
• Irritable bowel syndrome with constipation (IBS-C) in women 18 and older
• Opioid-induced constipation (OIC) in adults with chronic non-cancer pain

To learn more about how this medication works, check out our guide on how Amitiza works. For full prescribing details, see What Is Amitiza?

Common Side Effects of Amitiza

Most people who take Amitiza tolerate it well, but side effects do happen — especially in the first few weeks. The most common ones reported in clinical trials include:

• Nausea — This is the most frequently reported side effect, affecting up to 29% of patients. It's more common at the 24 mcg dose used for CIC and OIC.
• Diarrhea — Affects about 12% of patients. This makes sense given how the drug works — it increases fluid in your intestines.
• Headache — Reported in about 11% of patients.
• Abdominal pain or discomfort — About 8% of patients experience stomach pain, cramping, or general discomfort.
• Abdominal distension (bloating) — Affects about 6% of patients.
• Flatulence (gas) — Also about 6%.
• Vomiting — About 3% of patients.
• Loose stools — Some patients notice softer-than-expected stools, which is a milder form of the diarrhea side effect.

These side effects are generally mild to moderate and often improve as your body adjusts to the medication over the first few days to weeks.

Serious Side Effects: When to Call Your Doctor

While rare, some side effects from Amitiza require immediate medical attention. Contact your doctor or go to the emergency room if you experience:

• Difficulty breathing (dyspnea) — Some patients experience shortness of breath or chest tightness within 30 to 60 minutes of taking their first dose. This typically resolves on its own within a few hours but should be reported to your doctor.
• Severe diarrhea — If diarrhea is persistent, watery, or accompanied by signs of dehydration (dizziness, dry mouth, dark urine, rapid heartbeat), call your doctor right away.
• Fainting (syncope) — Though uncommon, some patients have reported fainting episodes.
• Low blood pressure (hypotension) — Symptoms include dizziness, lightheadedness, or feeling faint, especially when standing up.
• Severe nausea and vomiting — If nausea is so bad that you can't keep food or fluids down, contact your healthcare provider.
• Signs of bowel obstruction — Severe abdominal pain, inability to pass gas or stool, vomiting, and abdominal swelling. Amitiza should not be used if you have a known or suspected bowel obstruction.

Side Effects in Specific Populations

Women of Childbearing Age

Amitiza carries an important pregnancy warning. In animal studies, Lubiprostone was associated with fetal loss. Women who could become pregnant should:

• Have a negative pregnancy test before starting Amitiza
• Use effective contraception during treatment
• Stop taking Amitiza and contact their doctor immediately if they think they may be pregnant

Patients With Liver Problems

If you have liver disease (hepatic impairment), your doctor may prescribe a lower dose. For CIC, the adjusted dose is typically 16 mcg twice daily instead of 24 mcg. For severe liver impairment, the dose may be reduced to 8 mcg twice daily. Side effects may be more pronounced at standard doses in these patients.

Patients Taking Opioids

If you're taking Amitiza for opioid-induced constipation, be aware that certain opioids — especially Methadone — may reduce Amitiza's effectiveness. Talk to your doctor about potential drug interactions.

Older Adults

Clinical trials included patients 65 and older. While no major differences in safety were observed, older adults should be monitored for dehydration if diarrhea occurs, since they may be more vulnerable to fluid loss.

How to Manage Common Side Effects

If you're experiencing mild side effects, these strategies can help:

For Nausea

• Always take Amitiza with food and water. This is the single most effective way to reduce nausea. Taking it on an empty stomach significantly increases the risk.
• Eat a small snack or meal before taking your dose
• Avoid fatty or greasy foods around the time you take your medication
• If nausea persists, talk to your doctor — they may temporarily reduce your dose

For Diarrhea

• Stay well hydrated — drink plenty of water throughout the day
• Avoid caffeine and high-fiber foods until symptoms settle
• If diarrhea is frequent or persistent, your doctor may adjust your dose

For Bloating and Gas

• Eat smaller, more frequent meals
• Avoid carbonated drinks and gas-producing foods (beans, broccoli, cabbage)
• Light physical activity like walking can help

For Headache

• Over-the-counter pain relievers like Acetaminophen (Tylenol) are generally safe to take with Amitiza
• Stay hydrated and get adequate rest

If any side effect becomes severe or doesn't improve after a few weeks, contact your doctor. They may adjust your dose or consider alternative medications.

Final Thoughts

Side effects are a normal part of starting any new medication, and Amitiza is no exception. The most common issue — nausea — can usually be managed by taking the medication with food. Serious side effects are rare but important to watch for, especially difficulty breathing after your first dose.

The key is communication with your doctor. Report any side effects that concern you, keep your follow-up appointments, and don't stop taking Amitiza without talking to your healthcare provider first.

Need help finding a pharmacy that has Amitiza in stock? Check availability on Medfinder.