Im just telling you what a prominent doctor told me whilst he was thinking out loud. Maybe I should visit my local shaman instead?
The fact doctors dont know about the sides, even ones who prescribe it on a daily basis, also says something of the rarity of the sides. The fact nobody is clear on the root cause is a different issue.
Following what Luckfax said earlier, there is one good way to tell the numbers of ‘lurkers’. Look at when new members have used Fin, you would expect ‘lurkers etc’ to have used Fin years ago. Most people joining only used fin/stopped in the last 1 yr.