· 2 min read · By Clinical Trials
The 90-Day Washout Rule in India: What Every Volunteer Should Know
Why Indian ethics committees require a 90-day gap between clinical trials, how the washout period is tracked, and what it means for your eligibility and safety as a volunteer.
Why the 90-day rule exists
If you take part in a clinical trial in India, you will usually be asked to wait at least 90 days before joining another study. This is called the washout period, and it exists to protect you.
When you receive a study medicine, traces of it can stay in your body for weeks. If you join a second trial too soon, the leftover medicine can interfere with the new study, put your health at risk, and make the results unreliable. Ethics committees and the Drugs Controller General of India expect research centres to enforce this gap.
How the washout period is counted
The 90 days are counted from your last dose in the previous study, not from the day you signed up or the day the study ended. For example, if your final dose was on 1 July, you become eligible for a new study around 29 September.
Some studies require a longer gap, especially those involving medicines that stay in the body for a long time. The study team will always tell you the exact waiting period before you give consent.
How centres check your history
Responsible CROs verify your recent trial participation before enrolling you. On Clinical Study Pass, your verified dosing records carry the date of your last dose, so any research centre can confirm your washout status instantly through your QR checkpoint instead of relying on memory or paper letters.
This protects you twice: it keeps you safe from overlapping medicines, and it stops honest volunteers from being rejected because a centre cannot confirm their history.
What you should do as a volunteer
Always tell the screening team about any study you joined in the last year, even if you dropped out early. Hiding a recent participation can lead to serious health risks and permanent disqualification. Keep your own record of dosing dates, and ask for a participation certificate when a study ends.
The 90-day rule is not a barrier. It is a safety net that keeps Indian clinical research trustworthy, and it helps genuine volunteers build a clean, verifiable trial history.