The 100ml Question: Packing CBD for Flights, Eurostar and Winter Weekends

There is a specific kind of December morning where everything is going fine until you are standing in a departure lounge in your socks, watching a tiny amber bottle slide through the X-ray on its own. Nothing has gone wrong, exactly. It is just that you did not think about it in advance, and now you are doing all your thinking in public.

The fix is dull, cheap and takes about four minutes the night before. So here is the version we would hand to a friend: what counts as a liquid, why decanting is the one thing worth avoiding, and how to check a destination without spiralling into a two-hour internet hole.

First: yes, your oil is a liquid

This trips people up more than it should. Anything runny counts, and at UK airport security that means tinctures, sprays, dropper bottles and the majority of balms and creams, which sit in the gels and pastes bucket. Gummies are technically solid, but do not be surprised if a tray-side conversation happens anyway — especially with a bag of loose sweets in a sandwich bag that looks, from three feet away, like something else entirely.

For the record, none of this is a CBD-specific rule. It is the same queue, the same plastic tray and the same slightly tired security officer who has seen four hundred liquids before breakfast.

The 100ml rule, minus the folklore

UK airports work on container size, not contents. A 30ml bottle that is a third full is fine. A 200ml bottle with a thimbleful in the bottom is not, and no amount of earnest explaining will fix that at the belt — the bottle is the problem, not the volume.

Everything under 100ml goes into a single clear, resealable bag, usually around 20cm by 20cm. One bag per person at most UK airports. The bag comes out of your cabin case at security, so pack it near the top rather than under your jumper and a hardback book.

If you are travelling with a prescribed cannabis-based medicine rather than a shop-bought supplement, this is a different conversation from top to bottom. Carry your prescription and clinic letter, keep it in original packaging, and ring the airline in advance. The advice below is for the ordinary high street oil, not the pharmacy route.

Please don't decant it into a travel bottle

We understand the impulse. A big bottle feels like a risk, so you pour 15ml into a wee unmarked thing from the Boots travel aisle and off you go. It is the single most avoidable faff in this entire article.

Three reasons. One, security staff can only work with what is on the label — an unidentified brown liquid in an unlabelled bottle invites questions you would rather not answer at 06:15. Two, without the label you have lost the batch code, the strength and the ingredient list, all of which are the first things anyone would want to see. Three, droppers leak. Constantly. A cheap travel bottle with a tired silicone seal is how you end up with a hemp-scented wash bag in Newcastle.

Instead: keep the original bottle, keep the box if you still have it, and take a photo of the label and batch code on your phone. If you want to go one better, screenshot the order confirmation as well. It weighs nothing and takes ten seconds.

Leak-proofing, for people who have been burned before

A short, boring ritual that has never let us down:

• Run a strip of sticky tape around the cap. Yes, it looks ridiculous. Yes, it works.
• Put the bottle back in its box, or wrap it in a sock if the box went out with the recycling in January.
• Then into a small zip bag, and that zip bag into a second one. Double bagging costs pennies and saves a whole suitcase.
• Pack it upright, near the top of the bag, and do not cram the liquids bag so full that the seals are under pressure for four hours.

One related point: leave a bit of headspace in the bottle. A full-to-the-brim dropper bottle in a pressurised cabin is a small physics experiment you do not need to run.

Cabin bag, not the hold

Given the option, keep it with you. Not because of security — hold luggage goes through screening too — but because you are there to answer a question if one comes up, and because you keep an eye on the temperature. Holds get cold, and repeated freezing and thawing is not kind to an oil-based product. There is also the more basic argument: if a bottle leaks at altitude in the hold, everything you own for the next three days smells of it.

Eurostar, ferries and the rest of it

Eurostar runs the same 100ml liquids routine through a UK departure, so the packing advice transfers wholesale. Ferries and coaches tend to be looser, but loose is not the same as absent, and the bag still needs the label on it.

What matters far more than the method of travel is the destination. CBD sits in a genuinely awkward legal gap around the world: legal and widely sold here, treated as a controlled substance in some countries, and effectively zero-tolerance in a handful of others, regardless of what the label says. A few places take a very dim view of any cannabis-derived product, full stop, including the ones with no THC in them.

So before you zip the case, spend five minutes on the FCDO travel advice page for the country, then the country's own embassy or customs site. If it is still unclear, do not pack it. Being without a bottle for a week is a mild inconvenience. Being on the wrong side of a customs conversation is not.

Domestic UK flights are the easy case. Scotland, Northern Ireland, a hop to Bristol — same liquids rules, no border to cross.

Weekends away with no airport involved

Train to York, cottage in the Peak District, a friend's spare room in Cardiff: no 100ml theatre, but two things still apply. Temperature first — a bottle left in a cold car overnight in November, or in a glovebox in a rare bit of winter sun, is a bottle you may as well have left at home. Second, keep it in the original packaging in your wash bag so it does not end up loose at the bottom of a rucksack next to a set of keys.

A four-minute checklist

• Bottle is 100ml or under, and it is the original one, with the label on.
• Photo of the label and batch code saved on your phone.
• Cap taped, boxed or socked, double bagged, packed upright near the top.
• Destination rules checked, not assumed.
• In the cabin bag, not the hold.
• A one-line answer ready if anyone asks: it is a CBD supplement, here is the label.

None of this is legal advice, and none of it guarantees a smooth run — security staff can and do ask questions, and they are entitled to. But the difference between a shrug and a saga is usually just whether you did the boring bit the night before. Do that, and the bottle goes through the tray, comes out the other side, and gets on with being the least interesting thing in your luggage.