You can carry freshly expressed milk in an insulated cooler bag with frozen ice packs for up to 24 hours. After arriving at your destination, use the milk right away, store it in the refrigerator, or freeze it.

When traveling in 2026, the gold standard for storing breast milk is using an insulated cooler bag with frozen ice packs, which keeps milk safe for up to 24 hours. According to CDC guidelines, fresh milk can stay at room temperature for 4 hours, in a fridge for 4 days, or frozen for 6–12 months. For air travel, the TSA considers breast milk a "medically necessary liquid," allowing you to carry quantities larger than 3.4 oz; however, you must declare it at security for separate screening. A high-value strategy is to use solid ice packs, as slushy or melted gel packs may trigger additional searches. If you are on a long-haul flight, many airlines can provide ice to top off your cooler, but they are generally unable to store your milk in the onboard galley fridges.