What Is an FDA Complete Response Letter?

By Kristi Waterworth – Updated Feb 26, 2025 at 2:04 PM EST

Key Points

FDA complete response letters detail application flaws and data issues, guiding drug approvals.
These letters help investors predict drug approval timelines and potential market entries.
Understanding these letters helps investors gauge risks and opportunities in pharma bets.

When you're investing in pharmaceutical companies or biotechnology, it's important to understand the nuances of this particular industry. Along with learning how to interpret medical testing data, being able to decode an FDA complete response letter can help you better judge where medications and devices are in their approval process.

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About the Author

Kristi Waterworth has been a contributing real estate and financial expert at The Motley Fool, covering real estate, investing, and personal finance topics, since 2020. Kristi has been interviewed by various TV media outlets and podcasts for her real estate investing expertise – from residential real estate to digital real estate and everything in between. Kristi’s journalist career spans over 25 years, and she has written about real estate investing, homeownership, and home construction specifically for the last decade. She was also previously a licensed Realtor and general building contractor before the Great Recession and housing market collapse. She holds a bachelor’s degree in American history from Columbia College in Missouri.

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What information does an FDA complete response letter contain?

An FDA complete response letter is a very thorough document that can help guide pharmaceutical and biotech companies in the right direction regarding getting approval for their product. It contains four main types of information:

Description of the deficiencies in the application: If there's a problem with the application itself or with some information within the application, that will be described in the letter.

Review of the data: Applications for FDA approval require a great deal of data to accompany them, but it doesn't always mean the data that's presented is complete or answers FDA questions. The letter will describe the data that has been reviewed for products with multiple amendments to an application.

Inadequate data: If the data is inadequate to support approval, the letter will state this, as well. Sometimes, this happens before the FDA completes other steps, like inspections or reviewing potential product labeling.

Actions for approval: Complete response letters aren't just rejection letters; they also generally contain actionable information to help get the product approved. This can be literally anything from changing the labeling to changing the way that medical testing is performed.

What happens after a company gets an FDA complete response letter?

Once a pharmaceutical company or biotech company gets an FDA complete response letter, it has a few options. It can resubmit the application, withdraw the application, or request a hearing to contest a decision that there were sufficient grounds for denying the original application's approval.

If the company fails to do any of these things within a year of the complete response letter, it's automatically assumed that the company intends to withdraw the application, and it will be closed. At that point, the company would have to start over in the application process unless it had already requested or obtained an extension to respond.

What Is an FDA Complete Response Letter?

Key Points

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What is an FDA complete response letter?

What information does an FDA complete response letter contain?

What happens after a company gets an FDA complete response letter?

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