Keeping Vials Cold on a Road Trip
A parked car in the sun passes 50 °C (122 °F) within an hour, so the cooler rides in the cabin, never in the boot (trunk), and is not left in a parked car in the sun or overnight. For a day, an insulated cooler with frozen packs is enough; for a week or more, a compressor car fridge on the 12 V socket holds 2–8 °C (36–46 °F) on its own.
Last edited · written by PepPrep · not medical advice
A car is the hardest place to keep anything cold: a parked car in the sun passes 50 °C in an hour, and the boot (trunk) is worse than the cabin. The good news is that a car also has a power socket, which opens up options a plane does not.
Three ways, by trip length
- A day: an insulated cooler with frozen packs, packed as in the packing guide, on the back seat footwell out of the sun. Nothing else needed.
- Two or three days with hotels: the same cooler plus a plan for the packs. Hotel minibars are 10–14 °C and do not freeze anything, so ask reception about a freezer; most have one. An evaporative wallet needs only a tap and re-sets overnight, but it keeps things cool rather than fridge-cold. Ice packs get near fridge temperature for about a day at a time, and across several days only a compressor car fridge holds 2–8 °C on its own.
- A week, several people, or no hotels: a compressor car fridge on the 12 V socket holds a set temperature and runs off mains at night. It is the one time that product earns its price.
The two car mistakes
Leaving the cooler in the car overnight (the car cools, then it heats fast at dawn), and putting it in the boot, which has no air conditioning and sits over the exhaust. Cabin floor, behind the front seats, with the seat belt through the handle.
Border crossings
Driving across a border with supplies is usually simpler than flying, but the same rules apply: keep the product in its labelled packaging, carry any paperwork you have, and do not argue with an officer about what a vial is. The rules in the flying guide and official sources cover the US, Canada, the UK, the EU and Australia and apply at land borders too.
Proof
A temperature logger in the cooler is the only way to know what happened during the four hours you were driving. It costs less than one replacement vial.
Supplies mentioned: Travel · Travel checklist
Equipment only: nothing on this page is advice about what to inject, how much, or whether a product is fit to use. That comes from the product's labelling and whoever supplied it.