The Netherlands has strict regulations regarding medications that fall under the Opium Act, which includes many common prescriptions like ADHD medications (Ritalin), strong painkillers (opiates), and certain sleep or anxiety aids. To bring these into the country in 2026, you must possess a Schengen Certificate or a formalized medical certificate signed by your doctor and potentially legalized by the embassy. Even "common" stimulants or heavy sedatives can be confiscated if they are not in their original packaging with a valid prescription. It is vital to check the current Dutch Opium Act lists (List I and II) before travel to ensure you have the correct legal documentation.