Warehouse Temperature Excursions: What Does the FDA Expect?

A recently published FDA Warning Letter makes clear that recurring excursions beyond specified storage conditions cannot be addressed simply by revising procedures and providing training. The FDA expects immediate corrective actions, a batch-specific assessment of potential quality impacts, and a systematic retrospective review of all available temperature data.

What the FDA cited

The Warning Letter concerns a U.S. manufacturer of over-the-counter (OTC) drugs with a facility in Chatsworth, California. In its letter dated 08 September 2026, the FDA cited several deficiencies, including temperature excursions in a warehouse for finished drug products.

The FDA reviewed temperature data for the period from April 2025 through March 2026 and identified repeated periods of elevated temperatures. In one specific case, the temperatures recorded in the warehouse exceeded both the storage conditions stated on the product label and the firm’s internal temperature-monitoring protocol. The FDA also noted a risk of contamination in products exposed to elevated temperatures.

Why the Company’s Response was Inadequate

In response to the inspection, the company committed, among other things, to updating its procedures, revising its temperature-mapping protocols, retrospectively reviewing temperature-monitoring data, and training relevant personnel.

The FDA found the response inadequate because the company had not implemented immediate corrective actions or conducted a thorough retrospective assessment of the potential impact on products. The assessment should also have considered the potential formation of impurities and degradation products when products are exposed to heat.

The Warning Letter underscores that identifying an excursion and revising an SOP do not, by themselves, constitute an adequate product-impact assessment. Temperature data must be linked to the relevant storage conditions, time periods, and batches. The assessment should be scientifically sound and address potential effects on product quality, safety, and efficacy.

Relevance to GDP Practice

Although the Warning Letter concerns U.S. CGMP requirements for finished drugs and is addressed to a manufacturer, not a wholesaler, its central message is relevant to GDP practice: storage areas must be monitored and controlled to ensure that product-specific storage conditions are maintained. Excursions require clear alarm and escalation pathways, traceable documentation, and a timely decision on the status of potentially affected goods.

Temperature excursions should not be treated as isolated technical events. The duration and extent of the excursion, as well as the affected storage areas and batches, should be assessed. A robust review of historical data is also important: recurring excursions or gaps in monitoring may indicate a systemic problem.

For further information, including details of the other deficiencies cited, see the full FDA Warning Letter to kdc/one Chatsworth, Inc., on the FDA website.