To fly with medications and supplements in 2026, the general rule is to keep them in your carry-on bag rather than checked luggage to avoid issues with lost bags or extreme temperature fluctuations in the cargo hold. TSA does not require medications to be in original prescription bottles for domestic U.S. travel, but for international flights, keeping them in original pharmacy packaging with your name is highly recommended to satisfy customs. Liquid medications are exempt from the 3.4-ounce (100ml) limit, but you must declare them to a TSA officer before screening starts. For supplements like powders or pills, they are generally treated as standard items, though large quantities of powders may undergo additional X-ray screening. It is always wise to carry a copy of your prescription or a "Letter of Medical Necessity" from your doctor, especially for injectables or controlled substances, to ensure a smooth transition through security and international border checks.