Hi there,
Are you in the UK? If you are he should be able to get a drug called sativex which is Full spectrum cannabis, so THC and CBD. It isn’t easily available in all health authorities, some are really bloody awkward about it but there are many where it’s less of a battle. I got access to it a few years ago having been in California and bought some cookies, chocolates, and CBD oil. The CBD oil did nothing for me to be honest but the cookies and chocolate really did make a difference to the amount of pain I was in and how bad the spasms were so when I got back I mentioned it to my consultant and they referred me consultant who deals with sativex and she was happy because I knew I would respond to cannabis to prescribe it for me.
If I’m travelling abroad she prepares a letter for me outlining what it is, why I need it, with her details for the prescribing authority, and the date that the letter covers. I’ve never been asked for it, but in fairness I’ve never stuck my hand up and said I’ve got cannabis on me and dogs have never reacted to the smell for some reason. I make sure that I check the immigration rules for every country though, so last year when I was having a stopover in Singapore I didn’t take it with me because I just knew that they are incredibly strict about any kind of drugs and it wasn’t Worth the risk.
If he gets the CBD oil via a private prescription is he still able to get a letter from whoever prescribed it for every overseas trip? If so then it probably wouldn’t be a problem as long as the country you’re going to isn’t strict about cannabis, but I think you’d probably have to be comfortable with the risk of them confiscating and binning it.
Hopefully that’s useful:)