Relocating with an ongoing stimulant prescription is one of the few things better sorted before the move than after it, because Dutch rules on controlled medication limit what a newly registered huisarts (GP) can simply continue. Finding that out late is what turns a straightforward transfer into a gap in supply.
Register with a huisarts as early as possible, because continuity here depends on paperwork moving before your current supply runs out, not after. Stimulant ADHD medication (methylfenidate/Ritalin/Concerta, dexamfetamine) is a controlled substance under the Opiumwet, and in the Dutch system a huisarts generally can't start a stimulant prescription from scratch — that requires a psychiatrist or GGZ diagnosis. What a huisarts can often do, once you're registered and they've seen your documentation, is arrange a transfer of care that continues an existing, clearly documented diagnosis and prescription without making you restart the full diagnostic process — but this depends on the individual huisarts's comfort level and isn't guaranteed, so ask directly rather than assume. Bring everything: a letter from your current prescriber confirming diagnosis and dosage history, your most recent prescriptions, and ideally an English-language summary of your treatment history. Some people build in a buffer supply for the gap between registering and getting a Dutch prescriber sorted, since even a smooth transfer takes weeks. If your huisarts won't continue the prescription, expect a referral into the same GGZ system covered elsewhere — meaning the diagnosis wait times apply again, which is the real risk here. Starting this before you finish your last box of medication, not after, is the practical difference between a gap and no gap.