Approved in 2001, Zelnorm is a selective serotonin receptor agonist used for short-term treatment of irritable bowel syndrome (IBS) and for women over 65 who suffer from chronic constipation. Studies and reports to the FDA, however, reveal a strong association between taking Zelnorm and serious cardiovascular conditions, and lawsuits have followed as a result.

Side Effects

While Zelnorm was considered a breakthrough drug when introduced to the market, as it reduced pain and increased the gastrointestinal tract’s speed, patient experienced a wide range of side effects.

Many were on the mild end, including headache, dizziness, migraines, back pain, joint, muscle, and stomach pain, nausea, and gas.

However, some experienced more severe side effects:

  • Increased or severe stomach pain
  • Blood in stools
  • Ongoing diarrhea
  • Cramps
  • Feeling of fainting
  • Heart injuries
  • Angina heart attack
  • Strokes
  • Ischemic colitis
  • Rectal bleeding
  • Death

Studies and Warnings

Concerns over Zelnorm’s safety date back to 29 clinical trials. Out of 11,614 patients, 13 experienced life-threatening side effects, including heart attacks, strokes, and chest pains, when compared to the placebo group.

By 2004, the FDA received 20 reports of ischemic colitis, in which 14 required hospitalizations and four resulted in death, and more of severe diarrhea causing low blood pressure. The manufacturer was required to modify the label with warnings about these two conditions.

By 2007, the FDA requested Novartis Pharmaceuticals suspend its marketing campaign and withdraw Zelnorm. Other countries followed, but in the U.S., the FDA allowed Novartis to keep it on the market as an investigational new drug. Restrictions specify patients must be under 55 years of age and afflicted with IBS or chronic constipation. Patients cannot have a chronic heart problem and must be in critical need.


At one point, sales for Zelnorm reached $561 million, but by 2011, Novartis settled 124 lawsuits. With the medication available with less restrictions and minimal warnings for six years, Novartis’ negligence subjected many unsuspecting patients to extreme, life-threatening cardiovascular conditions.

If you were prescribed without a sufficient warning and then went onto have a heart attack, stroke, or similar cardiovascular complication, Trantolo & Trantolo has been reviewing and directing Zelnorm claims in Connecticut. Contact any of our law offices to have an experienced trial attorney review your claim.

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