Defining a temperature excursion

How the rules describe it

The frameworks agree on the substance and differ in emphasis, which matters for what each expects you to do.

WHO

defines an excursion as an event in which a product is exposed to temperatures outside the range prescribed for storage and/or transport.

EU GDP

the EU Guidelines on Good Distribution Practice (GDP) treat a temperature excursion as one kind of deviation in transport, which is reported to the distributor and recipient and investigated under a written procedure.

USP

the United States Pharmacopeia (USP) treats an excursion as a nonconforming event. One within the allowances USP builds into its storage definitions needs no further evaluation; one beyond them is evaluated against the product's stability data, which the manufacturer holds.

What EU GDP requires beyond excursions, chapter by chapter, is in our guide to good distribution practice.

Excursions the rules allow

Not every reading outside the storage range is a problem. USP builds allowances into its storage definitions, and a product within them needs no further evaluation. Several are set on mean kinetic temperature (MKT): the single steady temperature that would cause the same total degradation as the varying temperatures the product actually saw. For controlled room temperature, USP <659> currently defines storage at 20 to 25 °C and allows:

Excursions between 15 and 30 °C

in pharmacies, hospitals, warehouses, and shipping, provided the mean kinetic temperature does not exceed 25 °C.

Transient spikes up to 40 °C

for no more than 24 hours, under the same condition on mean kinetic temperature. Spikes above 40 °C are acceptable only if the manufacturer says so.

Refrigerated products have far less room. For controlled cold temperature, 2 to 8 °C, USP's chapter on mean kinetic temperature, <1079.2>, allows:

Excursions between 8 and 15 °C

for no more than 24 hours and never above 15 °C, provided the MKT over those 24 hours does not exceed 8 °C. Each excursion counts as a separate event.

Older editions of USP allowed brief spikes to 25 °C in refrigerated products; the current text does not, so that allowance no longer applies.

Exposure beyond these limits is evaluated against the monograph, the label, or the manufacturer's stability data. How the mean kinetic temperature is calculated, and where it may and may not be used, is in our guide to mean kinetic temperature.

USP has proposed redefining controlled room temperature as 15 to 25 °C, in line with WHO and the European Pharmacopoeia. The comment period closed on 30 September 2026; until the change is official, 20 to 25 °C applies.

What causes excursions

Excursions cluster where control passes from one party to another, or where a product waits. The guidance names the usual places:

The airport apron and the wharf

WHO advises moving temperature-sensitive shipments off the apron or wharf as quickly as possible, to avoid exposure to adverse conditions.

Customs

WHO asks for rapid clearance, because delays at customs can cause excursions.

Hubs and handovers

EU GDP asks for particular attention to temperature monitoring wherever a route involves unloading, reloading, or transit storage.

The vehicle

the UK's Medicines and Healthcare products Regulatory Agency (MHRA) notes that dark, solid-sided vans are more likely to get hot in summer and that curtain-sided trailers are at high risk of excursions, and that the probability of an excursion changes with season, geography, and altitude.

The packaging

EU GDP requires controls so that incompletely conditioned cool packs are not used by mistake and product does not touch them.

Some detected excursions turn out to be false alarms. For example, when monitoring devices are left running after the product has been put away, they record the receiving dock rather than the shipment.

Where each mode of transport is most exposed, from the apron to the last mile, is covered in our guide to pharmaceutical transport.

What happens after an excursion

WHO, EU GDP, and USP describe much the same sequence:

1. 1

   Report it

   Under EU GDP, an excursion in transit is reported to the distributor and the recipient. WHO's guidance spells out who tells whom: a deviation noticed in transit goes to the supplier, distributor, and recipient; one noticed by the recipient goes to the distributor.

2. 2

   Hold the product apart

   EU GDP requires products pending a decision on their disposition to be segregated, physically or electronically. WHO calls this quarantine: the product is isolated while a decision is awaited on its release, rejection, or reprocessing, and it does not go into saleable stock until then.

3. 3

   Assess it

   The assessment needs the record: how long the excursion lasted, how high or low it went, whether it stayed within the allowed limits, and the product's stability data. USP is explicit that mean kinetic temperature alone is not enough to judge the impact.

4. 4

   Decide

   The manufacturer or marketing authorization holder provides the stability data, and the quality function responsible for the product decides whether it is released, rejected, or reprocessed.

5. 5

   Investigate

   EU GDP asks for a procedure for investigating and handling excursions, so that the cause is found and the next shipment on the same lane does not repeat it.

Regulators are wary of a shortcut here. The MHRA has written that, where shipment conditions are not controlled, using stability data as a routine way to justify excursions would not be acceptable. Stability data can support a decision only when the temperature record shows what the product actually went through: how long, how far, and how often.

The point of stability budgets

A product's stability data usually allows some time outside its long-term storage condition without any significant risk to its quality. The Parenteral Drug Association's Technical Report 53 (2011) calls that allowance a stability budget, also known as time out of refrigeration, time out of storage, or time out of temperature, and describes how it is shared among everyone who handles the product: further manufacturing, packaging and labeling, transport, and the end user.

Because the budget is cumulative, every excursion spends part of it, and a product with a small budget needs its exposure tracked at each step of the chain. PDA presents this as industry consensus rather than a requirement, and the size of any budget comes from the product's own stability studies.

A budget is also what makes automatic release possible: when every product in a shipment stayed within its stability budget, including after an excursion the budget absorbed, the release can follow rules the quality team has set in advance. How that works, and what has to be in place first, is in our guide to product release after transport.

Caught in transit or reported on arrival

When an excursion is found matters as much as whether it happened. A single-use device read at the destination tells the receiving site about an excursion only once it is over: the product is quarantined and assessed, and the only question left is what happens to it. A device that reports while the shipment moves raises the alarm while the excursion is still happening, when a pallet can still be moved off an apron or a container's power restored.

No regulation requires real-time monitoring; the guidance requires that conditions are monitored, recorded, and can be demonstrated. But the MHRA makes the risk argument plainly: making an excursion more likely to be detected gives earlier warning and may help prevent it. We make that case, with the lanes where it does not pay, in why real-time temperature monitoring, and when it isn't worth it. How the device types differ is in our guide to cold chain monitoring devices, and what a tripped indicator can and cannot tell you in our guide to time-temperature indicators.

From detection to intervention

Controlant's devices send temperature and location while the shipment moves, and our MARS team watches shipments 24/7/365 against the limits a customer's quality team sets. When a reading goes outside the range for longer than allowed, the alarm reaches MARS, the customer's contact list, and the customer's own systems at the same moment, and MARS responds by the customer's work instructions. On a Saga device the excursion also shows on the device itself: an alarm bell on the display, an alarm LED that flashes every five seconds, and the minimum and maximum temperatures recorded, as the Controlant Support Center describes.

Every alarm and every action is recorded on the shipment's record, which is the record the quality team decides on, and Zero-Touch Release can release product automatically when it stayed within its stability budget, based on rules the customer's quality team sets.