Gut bacteria tweak could boost Parkinson's drug response

NCT ID NCT03575195

Terminated Disease control Sponsor: University of California, San Francisco Source: ClinicalTrials.gov ↗

First seen Jun 26, 2026 · Last updated Jun 26, 2026

Summary

This study explores whether altering gut bacteria with an antibiotic (rifaximin) can improve motor symptoms and medication response in people with Parkinson's disease. Researchers will first analyze how gut bacteria relate to symptoms, then give some participants rifaximin and others a placebo. The goal is to see if reducing certain bacteria can help levodopa work better and reduce 'OFF' time. The trial is currently suspended.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: Rifaximin (an antibiotic)
What this could lead to: If it works, this could point toward a way to improve Parkinson's symptoms and make standard medications work better by adjusting gut bacteria.
What could go wrong: This is an early, small trial that is currently suspended. The antibiotic approach may not change symptoms meaningfully, and gut bacteria changes might not last.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Get updates

Get notified about this study

Sign up to get updates when this study changes or when new studies for PARKINSON DISEASE are added.

Our safety recommendation!

By submitting, you agree to our Terms of use

Conditions

The condition(s) this trial relates to.

Parkinson disease

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

PARKINSON DISEASE

Contacts and locations

Locations

University of California San Francisco

San Francisco, California, 94115, United States

More trials for these conditions

Other studies related to the condition(s) this trial covers.