Ethosuximide Fails to Ease IBS Pain, Study Finds

A recent randomized clinical trial published in JAMA Network Open has found that ethosuximide, a calcium channel blocker, does not provide significant relief from abdominal pain associated with irritable bowel syndrome (IBS) and is linked to higher rates of treatment discontinuation due to adverse effects. The findings, released on February 20, 2026, challenge previous research suggesting that inhibiting T-type calcium channels could be a viable therapeutic approach for IBS-related pain.

Understanding the Study

The double-blind, placebo-controlled trial involved 124 adults diagnosed with IBS according to Rome IV criteria. Participants, recruited from 10 gastroenterology departments in French university hospitals, reported abdominal pain intensity of at least 4 out of 10 during a seven-day baseline period. They were then randomly assigned to receive either ethosuximide or a placebo for 12 weeks.

Researchers evaluated the “responder rate” as the primary endpoint – defined as a minimum 30% reduction in average abdominal pain intensity coupled with a Subject Global Assessment score indicating considerable or complete relief. Secondary outcomes included safety, IBS symptom severity, and quality of life.

Key Findings

The study revealed no statistically significant difference in responder rates between the ethosuximide and placebo groups (26.6% vs. 23.3%, respectively; relative risk, 1.14; 95% CI, 0.61-2.11). Similar results were observed in a modified intention-to-treat analysis.

Notably, treatment discontinuation rates were significantly higher in the ethosuximide group (47%) compared to the placebo group (22%). This disparity was largely attributed to adverse events. A total of 463 adverse events were reported across both groups, with a greater incidence among those receiving ethosuximide.

Common adverse events associated with ethosuximide included headache, sleep disturbance, fatigue, nausea, abdominal pain, and dizziness. There were no significant differences between the groups in secondary outcomes, such as IBS symptom severity or quality of life scores.

Implications for IBS Treatment

The authors concluded that ethosuximide is not an effective treatment for abdominal pain in IBS patients and is less well-tolerated than a placebo. They suggest that future research should focus on developing more selective T-type calcium channel modulators with improved safety profiles.

“These findings suggest that simply blocking T-type calcium channels isn’t enough to alleviate IBS pain,” explains Dr. Nicolas Kerckhove, lead author of the study. “More targeted approaches are needed to address the complex mechanisms underlying visceral hypersensitivity in IBS.”

What is IBS?

Irritable Bowel Syndrome (IBS) is a common disorder that affects the large intestine. It causes a variety of symptoms, including abdominal pain, cramping, bloating, gas, diarrhea, and constipation. IBS is considered a disorder of the gut-brain interaction, meaning that problems with communication between the brain and the digestive system can contribute to symptoms.

The cause of IBS is not fully understood, but factors that may play a role include abnormalities in gut motility, visceral hypersensitivity, gut microbiota imbalances, and psychological factors.

Sources: JAMA Network Open, PubMed, Conexiant