Phase 4 Clinical Trials
Phase 4 trials study drugs that are already FDA-approved. They monitor long-term effectiveness, side effects, and optimal use in broader populations.
About Phase 4
Phase 4 trials (post-marketing studies) are conducted after a drug has received FDA approval. They gather additional information about risks, benefits, and optimal use in diverse patient populations over longer time periods.
Top Conditions
Top Sponsors
Frequently Asked Questions
Phase 4 trials (post-marketing studies) are conducted after a drug has received FDA approval. They gather additional information about risks, benefits, and optimal use in diverse patient populations over longer time periods.
There are currently 828 Phase 4 clinical trials tracked in our database. These trials span multiple conditions and are run by a mix of pharmaceutical companies, academic institutions, and government agencies.
The conditions with the most Phase 4 trials include Dry Eye (15 trials), Urinary Tract Infections (13 trials), Hemophilia A (13 trials), Cataract (11 trials), Depression (10 trials).
To participate in a Phase 4 trial, browse the conditions below to find relevant trials, review the eligibility criteria, and talk to your doctor about whether participation is appropriate for your situation.
Trial data sourced from the ClinicalTrials.gov API. This site does not provide medical advice, always talk to your doctor about clinical trial participation.
Source: ClinicalTrials.gov, 2026.