Can I leave a clinical trial once I've started?
Yes — always. Participation in a clinical trial is voluntary at every moment. You can withdraw at any time, for any reason, without giving an explanation, without penalty, and without losing access to any standard medical care you're otherwise entitled to. This right is one of the core elements of informed consent and is explicitly protected by federal regulations. To withdraw, simply tell the research coordinator or principal investigator — verbally is fine, though most sites will ask you to sign a brief withdrawal acknowledgment for documentation. The coordinator will typically ask whether you want to continue any follow-up safety visits or labs (recommended for your safety after stopping a study drug). You'll still receive any compensation you've already earned for completed visits, though future milestone or completion bonuses may not be paid. If you withdraw due to a side effect or concern, the site will document it and report any adverse events to the sponsor and IRB.