A temperature excursion is any time a medicine has been outside its labelled storage range, in a fridge, a room or a vehicle. This page walks through what UK guidance expects, from the first minutes to the final record. The one thing to remember: keep the stock cold and quarantined, and decide nothing, neither use nor disposal, until each product has been assessed and the reasoning written down.
Why it matters
Why a few degrees matter
A medicine is licensed for the storage conditions on its label. UKHSA explains that most UK vaccines tolerate short excursions and lose potency gradually, so a warm reading is not automatically a write-off (UKHSA vaccine incident guidance). Freezing is different: it can denature proteins, break the bond between an aluminium adjuvant and the antigen, and crack vials, so UKHSA says any vaccine known to have been below 0 °C should be disposed of.
The harm runs both ways. Compromised stock may protect patients less, and UKHSA describes incident control teams deciding whether people need revaccinating. Discarding sound stock on a worst-case assumption is costly too: UKHSA reported £6.4 million of vaccine wastage in 2025, 84% of it avoidable (Vaccine Update 369).
In wholesale, the MHRA Inspectorate is blunt. Its 2020 transport post says it is "rare to find sound scientific justification" for accepting a load after an excursion, and that the most common reason for acceptance is commercial (MHRA Inspectorate blog, 2020).
What the rules say
The legal duty and the GDP layer
For wholesalers the starting point is law. Regulation 43 of the Human Medicines Regulations 2012 makes compliance with the GDP guidelines a condition of the licence, and the MHRA enforces it through inspection. The EU GDP guidelines say in 9.2 that a transport excursion should be reported to the distributor and the recipient and handled under a written procedure, and in 6.3 that any deviation affecting a returned cold chain item needs a risk assessment showing the product's integrity.
The MHRA's working detail sits in Inspectorate blog posts. The 2016 receipt and storage post expects records to show every deviation and the corrective action, with the RP informed. The 2016 transport post discourages using mean kinetic temperature (MKT) to excuse an excursion "without robust supporting information and methodology". In Ireland, the HPRA's IA-G0011 defines an excursion as a deviation "for any duration of time": notify the RP, quarantine, consult the marketing authorisation holder, document, correct, and tell the HPRA at once if a recall may be needed.
Healthcare settings: UKHSA, SPS and the professional bodies
In GP practices and pharmacies, vaccine excursions follow UKHSA's vaccine incident guidance, which builds on Green Book chapter 3. A one-off rise above +8 °C lasting under 20 minutes, for example during restocking, needs only the cause recorded and the thermometer reset. This is NHS clinical guidance for vaccine providers and does not apply to WDA or MIA holders: under GDP and GMP every excursion is a deviation. For vaccine providers, UKHSA also says a recorded minimum between 0 °C and +2 °C is unlikely to have affected vaccines where the fridge temperature has been verified; in wholesale, any reading below +2 °C is an excursion needing MAH assessment. Some manufacturers accept rounding, so +1.5 °C to +8.4 °C may count as in range, but only where that manufacturer confirms it. In England incidents go to the local NHS England screening and immunisation team (SIT); Northern Ireland routes them through the PHA.
For other medicines, NHS SPS's Managing temperature excursions is the working method: quarantine, record the peak and the time out of range, and assess each product against its SmPC, the SPS refrigerated medicines stability tool or the manufacturer. The RPS (2018, archived but not withdrawn) says using a medicine outside its range needs a full risk assessment and a written excursion procedure, and CQC's GP mythbuster 17 expects a written policy on what to do after a breach.
What good looks like
The first hour: contain, then assess
SPS and UKHSA describe the same response. The instinct in the moment is to bin everything or put it straight back into use, and both are premature. SPS says most medicines should go back into a fridge while they are assessed, quarantined and labelled "DO NOT USE", moved to another fridge if the first has not recovered, and that frozen stock stays in a freezer (SPS). UKHSA adds that a failed fridge should be left switched on with its probes undisturbed, so an engineer can see what happened.
The record is part of the response, not an afterthought. SPS's minimum is who you are, when the excursion happened and how far out of range it went, the medicines and batch numbers affected, what advice you sought and from whom, and what you changed to stop it happening again. SPS also asks you to note any previous excursion, because stability allowances are not unlimited and repeated excursions add up.
- Fix and containFix any obvious cause such as an open door, keep the door shut, and check the sensor is placed correctly and working.
- Quarantine coldLabel stock DO NOT USE and keep it at +2 °C to +8 °C, in another monitored fridge if needed. Discard nothing yet.
- Establish the factsPeak, minimum and time out of range, from a logger if you have one. Without one, assume it began at the last reset.
- Assess each productSmPC, SPS stability tool or manufacturer. For vaccines, the SIT and the manufacturer.
- Decide and labelUse, use with a shortened expiry, or discard. Cleared stock is labelled as involved in an incident and used first.
- Record and reportWho, when, how far, batches, advice and actions, through your incident route.
Drawn from SPS Managing temperature excursions and the UKHSA vaccine incident guidance. Vaccines follow the UKHSA route and reporting.
Outcomes, labels and follow-up
SPS lists three outcomes: usable with a shortened shelf life, usable with extra patient monitoring, or not usable and discarded. If you shorten an expiry, obscure the original date but keep the batch number visible, and record destroyed stock in your stock control system.
Where the fridge itself caused the excursion, UKHSA expects an engineer's inspection and, where possible, 48 to 72 hours of data logging before you trust it again. Power failures have their own routine on Power failures and contingency.
Worked example
An illustrative Monday morning
This is an illustrative example in a GP practice, not a real incident. Monday 08:30: the practice nurse reads the vaccine fridge before the first clinic. Current 5.1 °C, minimum 4.0 °C, maximum 10.6 °C. The thermometer was last reset on Friday at 17:30.
She does not reset it yet. She labels the stock "not for use", leaves it in the fridge, which is back in range, and checks the door seal and plug. The logger download shows a rise to 10.6 °C at 14:10 on Saturday, after the restock at the end of a weekend flu clinic, lasting about 50 minutes. UKHSA's 20-minute allowance covers only a one-off rise, with the vaccines in their original packaging and stored properly before, and evidence of how long it lasted. This one lasted longer than 20 minutes, so the allowance does not apply.
She records the readings, the logger summary, the cause and an inventory with batch numbers, then calls the screening and immunisation team. On their advice and the manufacturers', the practice lead records which products can be used, labels them to be used first, and notes where use is off-label. Only then is the thermometer reset, with a note on the chart. Without the logger, SPS's worst-case rule would have counted the stock as out of range from Friday 17:30, about 63 hours.
Where it is unclear
Where the sources disagree
Four questions recur. First, how short is too short to count: the HPRA says any duration, a 2018 MHRA reply on a 2016 blog post, answering a question about door openings on a clinical trial (IMP) fridge, says it is "not typical that very short excursions (e.g. 5 minutes or under) are reported in individual formal deviations, but these should still be noted", and UKHSA and SPS use 20 minutes for clinical settings (any duration, 5 or 20 minutes?). UKHSA's 20-minute allowance is NHS clinical guidance that does not apply to WDA or MIA holders, and it depends on knowing the duration (UKHSA's 20-minute allowance).
Second, low readings: UKHSA tells vaccine providers that a minimum between 0 °C and +2 °C is unlikely to have affected vaccines where the fridge temperature has been verified, while in wholesale any reading below +2 °C needs MAH assessment and SPS calls any excursion below 2 °C "always potentially significant" (readings between 0 and 2 °C). Third, MKT: discouraged by the MHRA Inspectorate in wholesale, allowed by the HPRA under set conditions, and described by SPS as a way to average out short peaks in clinical areas (mean kinetic temperature). Fourth, warm rooms, covered on Fridges and room storage and in 25 °C ceiling or a tolerance?.
Inspection findings
What inspectors have found
The MHRA's 2016 GDP deficiency data, the only full breakdown it has published, lists cold chain deviations without corrective and preventive action among its example findings. Its 2016 GMP deficiency data includes procedures that allowed MKT to be used to assess excursions without investigating the cause. The VMD reports inspectors finding diligently completed records that show out-of-range temperatures with no action taken (VMD blog). In each case the reading existed but the response did not.
In summary
The short version
- Quarantine first: label the stock DO NOT USE and keep it at +2 °C to +8 °C while it is assessed.
- Use nothing and discard nothing until it is assessed, except vaccines known to have frozen.
- Establish the peak and the duration; without a logger, assume it began at the last reset.
- Assess each product against its SmPC, the SPS tool or the manufacturer; for vaccines, involve the SIT.
- In clinical settings only, apply UKHSA's 20-minute allowance to a one-off event whose duration you can evidence; under GDP and GMP every excursion is a deviation.
- Record who, when, how far, which batches, what advice and what changed.