How Long Does IRB Approval Take?

IRB review timelines can vary depending on multiple factors, including study complexity, submission completeness, and review pathway. Understanding what drives these timelines — and how to protect them — is essential for keeping your study on schedule. 

IRB Approval Timelines at a Glance 

Not all IRB reviews follow the same path. The type of review your study requires directly determines how long IRB approval takes and what the process involves.

Review Type	Typical Timeline	WCG Timeline	When It Applies
Expedited  Review/ Exempt Determination	1 – 3 weeks	1 – 3 business days	Minimal‑risk studies; minor protocol amendments or research that meets federal exemption criteria (e.g., certain survey, educational, or benign behavioral studies).
Full Board Review	4 – 6 weeks	5 – 8 business days	Studies involving greater‑than‑minimal risk; first‑in‑human or complex interventional trials.

What Factors Affect How Long IRB Approval Takes? 

Even within standard timelines, several variables can accelerate or delay the IRB approval process. Regulatory and compliance leaders should account for the following when planning study timelines: 

• Submission Completeness – Incomplete applications are the leading cause of review delays. Missing consent forms, protocol gaps, or outstanding investigator credentials will halt review until resolved. 

• Study Complexity – First-in-human trials, pediatric studies, or research involving vulnerable populations may require additional scrutiny, which can extend full board review timelines. 

The IRB Approval Process: Step-by-Step 

Understanding each phase of the IRB approval process helps research teams anticipate what is required and identify where delays are most likely to occur. By streamlining your approach to these steps, your site can protect study timelines and improve overall workflow efficiency. 

Step 1: Pre-Submission Preparation 

Gather all required documentation, including the study protocol, informed consent forms, investigator credentials, and supporting materials. In the case of some industry-sponsored research, the sponsor will submit the main protocol, consent templates, IBs, and other applicable documentation. Then, following approval, the sites will be added. Ensuring application completeness at this stage is the single greatest factor in accelerating review speed and reducing administrative burden on your staff. 

Step 2: Submission and Administrative Check 

Submit your application through your designated institutional or central IRB electronic submission platform, such as WCG’s eReview Manager. The IRB staff will conduct an initial check for completeness and assign the appropriate regulatory review pathway — exempt, expedited, or full board. Prompt responses to any questions from IRB staff will help during this stage. 

Step 3: IRB Review 

Once accepted, your submission enters the active review queue. A designated IRB member conducts expedited reviews for minimal-risk research and makes exempt determinations. For studies involving greater-than-minimal risk, the protocol is scheduled for evaluation at the next convened full board meeting. Central IRBs, like WCG, meet several times per day, while institutional IRBs often meet on a weekly or monthly basis. 

Step 4: IRB Decision 

The review board issues one of the following determinations: approval, approval with conditions, deferral, or disapproval. The IRB provides actionable feedback, allowing your team to address any outstanding items and maintain regulatory compliance rapidly. 

Step 5: Approval Letter Issued 

Upon final approval, the board issues an official determination, which is called a certificate of action at WCG. Your research site may proceed with the study as soon as you receive this documentation and satisfy any applicable conditions outlined by the committee. 

Frequently Asked Questions 

How long does IRB approval take for a typical study? 

For some studies, IRB review takes approximately a week for exempt, two to four weeks for expedited, and four to six weeks for full board review. Factors such as submission completeness and study complexity can affect these timelines. WCG IRB’s streamlined processes and frequent board meeting schedule are designed to support faster-than-average turnaround times. WCG’s full board review is typically five to eight days, and expedited review is approximately one to three days.  

What is the IRB approval process? 

The IRB approval process involves submitting a complete application — including the study protocol, informed consent documents, and investigator information — to the IRB for ethical review. The IRB evaluates the study for participant safety, risk-benefit ratio, and regulatory compliance before issuing a determination. Learn more about federal IRB requirements from the Food and Drug Administration (FDA) and the Office of Human Research Protection (OHRP). 

How long does it take to get IRB approval for an expedited review? 

Expedited reviews by WCG IRB are typically completed within one to three business days. This pathway applies to studies involving no more than minimal-risk to participants, as defined under 45 CFR 46.110 and 21 CFR 56.110. 

What causes delays in the IRB approval process? 

The most common causes of IRB approval delays include incomplete or inconsistent submissions, missing consent form language, unresolved investigator qualification issues, and protocol deficiencies that require clarification. Working with an experienced IRB like WCG — and utilizing pre-submission support — significantly reduces the risk of preventable delays. 

What is the difference between expedited and full board IRB review? 

Expedited review is conducted by one or more designated IRB members and applies to minimal-risk research. Full board review requires convened review by the entire IRB committee and is required for studies involving greater-than-minimal-risk, including most clinical trials. The Office for Human Research Protections (OHRP), under the U.S. Department of Health and Human Services (HHS), provides detailed guidance on review categories. 

What documentation is required to submit for IRB review? 

Required documentation typically includes the study protocol, informed consent and assent forms, recruitment materials, investigator brochure or device description, and relevant regulatory submissions (e.g., IND/IDE).  

Protect Your Study Timeline with WCG IRB 

IRB approval is one of the first critical milestones on the path to study start-up. Delays here have a compounding effect across your entire trial timeline. WCG IRB’s combination of deep regulatory and ethical expertise, high-capacity review infrastructure, and dedicated sponsor support is designed to give your study the best possible foundation.