In 2025, there’s been a marked increase in FDA warning letters. During the second quarter of 2025 alone, the U.S. Food and Drug Administration (FDA) issued 172 warning letters. A notable enforcement surge occurred in September 2025 when the FDA released 80 warning letters in a single week. Although this surge has been attributed in part to the FDA’s expanded use of artificial intelligence—specifically the internal Elsa tool—it’s continued evidence that the FDA is focused on its mission of enforcement.

Warning letters are issued for many reasons. What often doesn’t get the focus it deserves are issues related to calibration and maintenance, such as missing calibration records, lack of preventive maintenance planning, and fractured audit trails. According to Blue Mountain research on recent warning letters citing calibration and maintenance issues, key observations included incorrect calibrations, lack of records and inadequate evidence, lack of validation, and lack of routine calibration and maintenance programs.

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