Amitiza (generic name: loperamide) is a medication used to treat acute or chronic diarrhea. It’s a non‑opioid antidiarrheal that slows gut motility, giving the intestines more time to absorb water and electrolytes.
How It Works
- Opioid‑receptor agonist (peripheral μ‑opioid receptors only – it does not cross the blood‑brain barrier in significant amounts).
- Reduces the frequency and urgency of bowel movements by decreasing intestinal muscle contractions.
- Helps to increase stool consistency and reduce abdominal cramping.
Typical Uses
| Condition |
Typical Reason for Use |
| Acute infectious diarrhea |
To relieve symptoms while the body clears the infection |
| Chronic diarrhea (e.g., IBS‑diarrhea subtype) |
Symptomatic relief, especially when other treatments fail |
| Diarrhea associated with inflammatory bowel disease (IBD) |
Short‑term symptom control |
| Post‑operative or chemotherapy‑related diarrhea |
Symptom relief when other options are limited |
It is not intended for treating constipation or for long‑term maintenance therapy unless directed by a doctor.
Dosage (Adults and Adolescents ≥12 yrs)
| Situation |
Initial Dose |
Maintenance |
Max Daily Dose |
| Acute diarrhea |
4 mg (2 × 2 mg) |
2 mg q4–6 h as needed |
16 mg |
| Chronic diarrhea |
4 mg at start, then 2 mg q6–8 h |
2 mg q6–8 h as needed |
16 mg |
| Pediatric <12 yrs |
Not FDA‑approved for this age group. Use only under specialist supervision. |
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If you’re using a loose‑form (Amitiza Lo) you’ll take 4 mg at the first dose, then 2 mg q4–6 h as needed.
Never exceed the maximum daily dose of 16 mg, and if diarrhea persists beyond 3 days, see a healthcare provider.
Common Side Effects
| Mild |
Moderate |
Severe |
| Dizziness, constipation |
Abdominal pain, nausea |
Severe constipation, fecal impaction |
| Mild bloating |
Rash or itching |
Respiratory distress (rare) |
| Dry mouth |
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- Constipation is the most frequent adverse effect. If it becomes severe or you can’t pass stool for several days, stop the drug and contact your provider.
Contraindications & Warnings
| Category |
Key Points |
| Contraindicated |
• Known hypersensitivity to loperamide or any component.
• Severe, bloody, or fever‑associated diarrhea.
• Use with caution in patients with ulcerative colitis or Crohn’s disease; treat underlying disease first. |
| Warnings |
• Cardiac risk: high doses (above recommended) can cause QT prolongation and torsades de pointes.
• Kidney impairment: Use with caution; monitor renal function.
• Liver disease: Loperamide is metabolized in the liver; use with caution. |
| Drug interactions |
• Cyclosporine, azoles, ritonavir, and other CYP3A4 inhibitors can increase loperamide levels.
• Opioid analgesics: combining them with loperamide can precipitate severe constipation or bowel obstruction. |
How to Take It
- Take with food: It improves absorption and may reduce stomach upset.
- Keep the bottle closed: Store at room temperature, away from heat, moisture, and children.
- Don’t crush or chew: The formulation is designed to release slowly.
What to Do If You Miss a Dose
- If you realize within a few hours, take it as scheduled.
- If it’s closer to the next dose, skip the missed dose. Do not double up.
When to Seek Medical Attention
- Persistent fever (>101 °F/38 °C) or bloody stools.
- Severe abdominal pain or cramping.
- Signs of bowel obstruction (e.g., vomiting, inability to pass gas or stool).
- Signs of allergic reaction (rash, itching, swelling, wheezing).
Bottom Line
Amitiza is a quick, over‑the‑counter solution for reducing the frequency of diarrhea and making stools more formed. It’s effective for most adults and adolescents, but it can cause constipation and, rarely, more serious cardiac or gastrointestinal complications if taken in excess or with certain medications.
If you have any underlying health conditions, are on other drugs, or have concerns about side effects, discuss it with a pharmacist or your doctor before starting. And remember—“Amitiza isn’t a cure for the cause of diarrhea; it’s a symptomatic relief tool.”