I have no idea how hard it is really but if it's true it is impossible, it is infuriating. People do research on substances that can kill a person with an invisible amount, blow up buildings, poison vast areas, all kinds of deadly things. But take a drug that any smart high-schooler can (and frequently does) access it - and it's impossible to research it! This is so infuriatingly insane.
There are plenty of pharmaceutical drugs out in the wild that have known side-effects. Chemotherapy completely nukes a person's body but is legal because the harm it induces is deemed worth the problem it solves (cancer).
Despite this, marijuana which is in easy circulation on the streets in dubious forms of dosage/strength, has such a political air over it that most countries still won't even look into the medical applications of it!
As a scientist, the double standards are incredibly frustrating!
In US I think it's even worse - it is known there are medical applications of it but the federal government just pretends they do not exist and still qualifies cannabis as "drug that has no known medical use". They don't refuse to look - they look, see, know it exists and still say "no, it doesn't exist".
