How long IRB approval takes depends almost entirely on which review track your study lands in: exempt review can finish in under a week, expedited review typically runs two to six weeks, and full board review usually takes one to three months. Most of the delay researchers actually experience comes from incomplete submissions, slow responses to reviewer questions, and prerequisites they didn’t know they had to complete first.
Exempt Review: Under a Week to Two Weeks
Exempt review is the fastest path. It applies to studies with negligible risk that fit into narrowly defined categories in federal regulations, such as research in normal educational settings, anonymous surveys and interviews where responses cannot be traced back to participants, and analysis of publicly available data.1eCFR. 45 CFR 46.104 – Exempt Research Benign behavioral interventions with adults, like puzzles or short videos with verbal or written responses, can also qualify.
Turnaround is typically less than a week, stretching to about two weeks if IRB staff requests minor clarifications or if there is a submission backlog. Despite the name, exempt does not mean you skip the IRB. At most institutions the IRB office still makes the formal determination that a study qualifies, because the federal government recommends against letting researchers make that call themselves.2HHS.gov. Exempt Research Determination FAQs
A note on scope: an anonymous survey does not automatically qualify. If your questions cover illegal drug use, criminal behavior, or other topics where a breach of confidentiality could harm participants, exemption is unlikely.
Expedited Review: Two to Six Weeks
Expedited review covers studies that involve no more than minimal risk but do not qualify for exemption. Federal regulations define minimal risk as risk no greater than what a person would encounter in everyday life or during routine medical exams.3eCFR. 45 CFR 46.102 – Definitions for Purposes of This Policy The category also covers minor changes to previously approved research. Instead of going before the full committee, expedited applications are reviewed by one or two experienced IRB members, usually the chair or a designee.4eCFR. 45 CFR 46.110 – Expedited Review Procedures
Plan on two to six weeks from the date your application is deemed complete. Some institutions with lighter caseloads turn expedited reviews around in under two weeks; others routinely take a month or more. The variability is wide because it depends on how busy the reviewers are and whether they request revisions.
Full Board Review: One to Three Months
Full board review applies to any study that poses more than minimal risk. Clinical trials of new drugs, research involving deception, and studies collecting sensitive information from vulnerable populations almost always land here. The full committee must convene to discuss and vote, and federal regulations require that a majority of members be present, including at least one whose primary expertise is nonscientific.5eCFR. 45 CFR 46.108 – IRB Functions and Operations
Expect one to three months. The driver is the meeting calendar. Most IRBs meet monthly, and your application has to be submitted well in advance to give members time to read it. Miss the submission deadline by a day and you wait for the next cycle. One published study of institutional IRBs found a median turnaround of about 40 days for full board reviews; another large university reported a median of 67 days.6National Library of Medicine. A Comparison of Institutional Review Board Models and Study Activation Timelines Add a round of requested revisions, which is common, and three to four months from initial submission to final approval is realistic.
Studies involving prisoners, pregnant women, or children carry additional federal requirements under Subparts B, C, and D. Those layers add both complexity and time.7HHS.gov. 45 CFR 46 Subpart B – Additional Protections for Pregnant Women, Human Fetuses and Neonates Involved in Research
Prerequisites That Add Weeks Before the Clock Starts
The review clock does not start when you begin preparing your application. It starts when the IRB accepts your submission as complete. Several prerequisites have to be in place first.
Human Subjects Training
Nearly every institution requires the principal investigator and all key study personnel to complete human subjects protection training before the IRB will accept a submission. The most widely used program is the Collaborative Institutional Training Initiative (CITI), whose certification typically lasts three years. If any team member’s certification has expired, the IRB will not begin reviewing your application until it is renewed.
Conflict of Interest Disclosure
Most institutions also require the principal investigator and co-investigators to have a current financial conflict of interest disclosure on file, usually updated within the past year. This is a separate requirement from human subjects training and has its own renewal cycle. Industry collaborations or personal equity in a company that could benefit from the research will draw closer scrutiny of your conflict management plan.
Institutional Assurance
Federally funded research requires that your institution hold a Federalwide Assurance filed with the Office for Human Research Protections. The FWA is the institution’s formal commitment to comply with federal human subjects protection requirements.8HHS.gov. Terms of the Federalwide Assurance for the Protection of Human Subjects Individual researchers do not apply for it, but a small organization or startup obtaining an FWA for the first time can add significant delay.
Where the Real Delays Come From
Review type sets the baseline. Almost everything else extends it.
- Incomplete applications. Missing a signed consent form, a recruitment flyer, or a data management plan sends the submission back before review begins. That round trip alone costs one to three weeks.
- Revisions during review. Even complete applications rarely clear without questions. Reviewers may ask you to clarify confidentiality protections, simplify consent language, or justify the risk-benefit balance. Each revision cycle adds one to four weeks depending on how quickly you respond.
- Informed consent problems. Federal regulations require specific elements in the consent form: a clear statement that the study is research, a description of foreseeable risks and potential benefits, confidentiality protections, a statement that participation is voluntary, and contact information for questions. Consent forms with overly technical language, missing elements, or exculpatory clauses that appear to waive participants’ legal rights get flagged for revision.9eCFR. 45 CFR 46.116 – General Requirements for Informed Consent
- Institutional workload. Submission volume surges in early fall and late spring around academic calendars. Submitting in peak season means a longer queue.
- Meeting schedules. Most institutional IRBs meet once a month, and some skip meetings during summer or winter breaks. Missing a submission deadline by a day pushes you into the next cycle.
How to Shorten Your Timeline
The gap between a smooth three-week process and a grinding three-month one usually comes down to preparation.
Use your IRB’s pre-submission consultation service if one exists. Sitting down with an IRB coordinator before you submit lets them flag issues that would otherwise come back as revision requests weeks later. This single step probably saves more time than any other.
Write your consent document at a sixth- to eighth-grade reading level. Reviewers read hundreds of these, and consent forms stuffed with jargon are the ones that get sent back. Start with a plain-language summary of what participants will actually experience, then cover the required elements in order. Do not reuse a consent template from a different institution without checking whether it matches your IRB’s preferred format.
Treat every reviewer question as due yesterday. The review clock stops while your application sits in your inbox. If a full board study requires re-review at the next meeting, a slow response can push you out by an entire month.
Verify current training certifications and conflict of interest disclosures for every person on your study team before submitting. An expired CITI certification for a co-investigator is trivial to fix but can freeze your entire application.
Commercial IRBs Move Faster Than Academic Ones
Researchers in industry-sponsored clinical trials or at organizations without their own IRB often use a commercial (independent) IRB. Companies such as WCG IRB and Advarra review protocols on a fee-for-service basis, and their turnaround tends to be significantly faster. One industry report found commercial IRBs returning decisions in as few as 3 to 8 days, compared with a median of about 40 days for institutional full board reviews.6National Library of Medicine. A Comparison of Institutional Review Board Models and Study Activation Timelines
The speed difference comes from structure. Commercial IRBs employ dedicated full-time reviewers, meet more frequently, sometimes weekly, and are not juggling teaching and administrative loads. The tradeoff is cost. Commercial IRB fees can run into the thousands of dollars per protocol, while most university IRBs charge researchers nothing. For federally funded academic work, the institutional IRB is usually the default. For industry-sponsored work, especially multi-site clinical trials, a commercial IRB is often specified in the study contract.
If your study runs at more than one site in the United States and receives NIH funding, federal policy requires a single IRB of record rather than separate approvals at every participating institution.10NIH. Single IRB for Multi-Site or Cooperative Research The impact on timelines has been mixed. A comparison of single-IRB and local-IRB models in a large multi-site consortium found the median time from submission to approval was essentially the same, about 19 to 20 business days.6National Library of Medicine. A Comparison of Institutional Review Board Models and Study Activation Timelines Reliance agreements between institutions still take time to set up, so single IRB does not automatically mean faster.
Approval Isn’t Permanent
One boundary worth flagging when you’re planning around a timeline: getting the approval letter is not the finish line for full board studies. Federal regulations require continuing review at intervals appropriate to the risk level, and no less than once per year for studies that required full board review.11eCFR. 45 CFR Part 46 – Protection of Human Subjects If approval lapses because you missed the continuing review deadline, all research activities with participants must stop, with no grace period.12HHS.gov. Continuing Review Guidance (2010) Mark the expiration date on your calendar the day the approval letter arrives. Studies that qualified for exempt or expedited review generally do not require annual continuing review under the revised Common Rule, unless the IRB determines otherwise.