What documents besides the prescription must I have to bring medication into the Netherlands?
Have a copy of your prescription--the same information as found on your prescription bottles.
If any are controlled substances or narcotics, make sure it's allowed in the country and perhaps keep them in their original container.
As long as you can prove the prescriptions are yours, and you're only bringing enough for the length of your visit and a few days more, you'll be fine. Contrary to popular belief, they are not out to take your statin drugs.
For short trips, I just keep my prescriptions in my daily pill case. For longer ones, I also will bring the original prescription bottles (to refill my pill case.) My medical records are retrievable from Epic’s MyChart and I never bring any paperwork. I have never been asked about my prescriptions and I know of no one who ever has asked either.
For the Netherlands in particular, I also will avoid eating their brownies as those things can make me too wonderful for words. Some people are into that but, hey, I am fundamentally a boring person!
Happy travels!
You know we are talking a pretty serious thing. One aspect is legal, one is having a holiday messed for no reason that couldn't be avoided. So I deleted my answer and think you will do better following the guidance of professionals. There seems to be some consensus you might want to consider.
https://wwwnc.cdc.gov/travel/page/travel-abroad-with-medicine
https://travel.state.gov/en/international-travel/planning/guidance/medicine-health.html
https://www.globalsupport.harvard.edu/travel/advice/tips-traveling-medication
https://www.gov.uk/take-medicine-in-or-out-uk
https://www.webmd.com/a-to-z-guides/travel-medication.
These are just the first to pop up on a Google search. Dig deeper until you are satisfied with a plan.