What to Know About Ibsrela Side Effects

If you've been prescribed Ibsrela (Tenapanor) for irritable bowel syndrome with constipation (IBS-C), you're probably wondering what side effects to expect. Like any medication, Ibsrela can cause side effects — but most of them are manageable, and serious reactions are rare.

This guide breaks down the common and serious side effects of Ibsrela based on FDA clinical trial data, covers special populations, and tells you exactly when you should call your doctor.

What Is Ibsrela?

Ibsrela is a prescription medication made by Ardelyx that treats IBS-C in adults. It works by blocking a sodium transporter (NHE3) in the intestines, which increases fluid in the gut and helps relieve constipation and abdominal pain. You can learn more in our complete guide to Ibsrela.

The standard dose is 50 mg taken twice daily — once before breakfast and once before dinner.

Common Side Effects

In clinical trials, these were the most frequently reported side effects of Ibsrela:

• Diarrhea — 16% of patients. This is the most common side effect by far. Given that Ibsrela works by drawing more fluid into the intestines, diarrhea is an expected and somewhat predictable effect.
• Abdominal distension (bloating) — 3% of patients. Some people notice their stomach feels fuller or more swollen than usual.
• Flatulence (gas) — 3% of patients. Increased gas is another GI-related side effect that tends to improve over time.
• Dizziness — 2% of patients. This can be related to fluid shifts or dehydration, especially if diarrhea is significant.

Most of these side effects are mild to moderate and tend to occur early in treatment. Many patients find they improve after the first few weeks as the body adjusts.

Serious Side Effects

While rare, some side effects of Ibsrela require immediate medical attention:

• Severe diarrhea leading to dehydration — If diarrhea becomes severe or persistent, it can cause dehydration. Signs include extreme thirst, dark urine, dizziness when standing, and feeling faint. This is the most important side effect to watch for.
• Rectal bleeding — Any blood in your stool or rectal bleeding while taking Ibsrela should be reported to your doctor right away.
• Severe abdominal pain — While mild cramping can occur, intense or worsening abdominal pain is not normal and should be evaluated.
• Electrolyte imbalances — Significant fluid loss from diarrhea can throw off your body's electrolyte balance. Symptoms include confusion, irregular heartbeat, muscle weakness, and numbness or tingling in your hands and feet.

Boxed Warning: Pediatric Risk

Ibsrela carries an FDA boxed warning — the most serious type of safety warning — about the risk of severe dehydration in children:

• Contraindicated in patients under 6 years of age due to risk of death from dehydration (observed in young juvenile rats during testing).
• Avoid use in patients 6 to 12 years of age.
• Not established for patients under 18 years of age — Ibsrela is approved only for adults.

This warning is important for households with children. Keep Ibsrela stored safely and out of reach of children at all times.

Special Populations

Pregnant Women

Ibsrela has minimal absorption into the bloodstream, so fetal exposure is expected to be very low. However, there are no adequate studies in pregnant women. Talk to your doctor if you are pregnant or planning to become pregnant.

Breastfeeding

It is not known whether Ibsrela passes into breast milk. Given the minimal systemic absorption, risk is considered low, but you should discuss this with your healthcare provider.

Patients with GI Obstruction

Ibsrela is contraindicated in patients with known or suspected mechanical gastrointestinal obstruction. If you have a history of bowel obstructions, make sure your doctor is aware before starting this medication.

How to Manage Common Side Effects

Here are practical tips for handling the most common Ibsrela side effects:

Managing Diarrhea

• Stay hydrated — Drink plenty of water and electrolyte-containing fluids throughout the day.
• Monitor frequency — If you're having more than 3-4 loose stools per day, take note and mention it to your doctor.
• Don't skip meals — Since Ibsrela should be taken before meals, maintaining a regular eating schedule helps keep dosing consistent.
• Give it time — Diarrhea often improves within the first few weeks of treatment.

Managing Bloating and Gas

• Eat smaller, more frequent meals.
• Avoid foods that tend to increase gas (beans, carbonated drinks, cruciferous vegetables).
• Consider over-the-counter simethicone (Gas-X) if gas becomes bothersome — but check with your doctor first.

Managing Dizziness

• Stand up slowly from sitting or lying positions.
• Make sure you're drinking enough fluids.
• If dizziness persists, contact your provider — it could signal dehydration.

When to Call Your Doctor

Contact your healthcare provider right away if you experience:

• Severe or worsening diarrhea that doesn't improve
• Signs of dehydration (dark urine, extreme thirst, dizziness, fainting)
• Blood in your stool or rectal bleeding
• Severe abdominal pain
• Confusion, irregular heartbeat, or muscle weakness
• Any allergic reaction (rash, swelling, difficulty breathing)

If your side effects are mild but bothersome, it's still worth mentioning them at your next appointment. Your doctor may adjust your treatment plan or suggest ways to manage them better.

Final Thoughts

Most people who take Ibsrela tolerate it well. Diarrhea is the most common side effect, but it's usually manageable and often improves over time. Serious side effects are rare, but knowing what to watch for — especially signs of dehydration — is important.

If you're considering Ibsrela or have just started taking it, keep the lines of communication open with your doctor. Don't hesitate to reach out if something doesn't feel right.

Looking for Ibsrela at a pharmacy near you? Medfinder can help you find it in stock.