Frequently Asked Questions

ClinicalTrials.gov is the official U.S. registry of clinical studies maintained by the National Library of Medicine (NLM) at the National Institutes of Health (NIH). Sponsors and investigators are required by law to register certain studies and report results. The database contains over 500,000 registered studies worldwide.

PlainTrial shows study titles, status (recruiting, active, completed, etc.), phase, condition, intervention type, sponsor, eligibility criteria, study locations, and key dates, all sourced from ClinicalTrials.gov bulk data exports.

Use the search or filter pages to narrow by condition, location, phase, or status. Filter by 'Recruiting' status to find trials currently enrolling. Check eligibility criteria on the trial detail page. Always contact the study coordinator directly to verify your eligibility, eligibility criteria on ClinicalTrials.gov can be complex and may have been updated since our data snapshot.

Phase 1 trials test safety and dosing in a small number of participants. Phase 2 trials evaluate efficacy and side effects in a larger group. Phase 3 trials compare the treatment to existing standard treatments in large populations. Phase 4 trials occur after FDA approval and monitor long-term effects. Some trials are Phase 1/2 or 2/3 (combined), and observational studies may show N/A.

No. PlainTrial is built from a snapshot of ClinicalTrials.gov data. Trial status, participant counts, eligibility requirements, and study locations can change at any time. Before considering participation in any trial, always verify the current information directly at ClinicalTrials.gov by searching the NCT number.

No. Eligibility criteria are shown as-is from ClinicalTrials.gov, but determining actual eligibility requires medical evaluation. A trial's coordinator or principal investigator is the only person who can determine if you qualify. Contact the study team listed on the trial page or at ClinicalTrials.gov.

An NCT number (e.g., NCT04580563) is the unique identifier assigned to each study registered on ClinicalTrials.gov. You can use this number to look up the current, official record for any trial directly on ClinicalTrials.gov.

Yes. ClinicalTrials.gov includes both US-based and international studies, and our database includes all of them. We primarily focus on US trials but international studies are searchable. Location filters can help you find trials by country or region.