Duty-free liquids over 100 ml can be confiscated at transfer security if they are not in a sealed tamper-evident bag (STEB) with the receipt inside. Even sealed bags can be refused in some countries, especially when connecting in the US. The safest options are to buy duty-free at your last connecting airport, or pack liquids in checked luggage.
You bought a bottle of perfume in the first airport, and an hour later a security officer drops it in the bin at your connection. It’s one of the most common layover frustrations, and it’s easy to avoid.
Why it happens
Most countries limit carry-on liquids to containers of 100 ml or less in a single clear bag. When you change planes, you often go through transfer security again, and the limit applies to everything in your bag, including duty-free from your first airport.
Duty-free shops get around this with a security tamper-evident bag (STEB): a sealed bag with the receipt inside. Many airports accept STEB items at transfer security, but not all do, and acceptance can vary.
The 5 rules
- Buy at your last airport. If you’re flying A → B → C, buy at B. No transfer security means no risk.
- Keep the STEB sealed until your final destination, with the receipt visible inside.
- Don’t buy before a US connection. Arriving in the US means customs, then re-screening. Put liquids in your checked bag at the bag re-check point.
- Check the connecting airport’s rules. Some airports have newer scanners and relaxed limits, but your connecting airport’s rules are what count.
- When in doubt, check it in. Wrap bottles in clothes inside your checked bag.
What about the new scanners?
Some airports have installed CT scanners that allow larger liquids in carry-on. But rules have been tightened and relaxed more than once in recent years, and they differ between airports. Never assume your connecting airport works the same way as your departure airport.
Quick reference
| Item | Safest approach |
|---|---|
| Duty-free alcohol | Buy at last airport, or keep in sealed STEB |
| Perfume over 100 ml | Sealed STEB, or checked bag |
| Toiletries | Under 100 ml in a clear 1-litre bag |
| Baby milk/food & medicines | Usually allowed in reasonable amounts. Carry prescriptions and be ready to show them |
| Water bottle | Bring it empty and refill after security |
Related: How long should a layover be? · Airport layover guides
Frequently asked questions
Can I take duty-free alcohol on a connecting flight?
Usually yes, if it stays sealed in the tamper-evident bag with the receipt visible and you do not open it until your final destination. Rules at transfer security vary by country, so buying at your last airport is safest.
What is a STEB?
A security tamper-evident bag (STEB) is the sealed bag duty-free shops use for liquids over 100 ml. It shows if it has been opened, which allows security screeners to accept the liquids during a connection.
Why did security take my duty-free on a US connection?
When you arrive in the US and connect onward, you clear customs and then pass security again. Liquids over the limit must go into your checked bag at the re-check point, or they may be taken at security.