Some people report 1,4bdo being very harsh on their body, with a nasty hangover and just not a good feeling overall.
This is entirely individual first of all but there may be some science to it.
Take l-theanine! It seems to help your liver to correctly metabolize 1,4bdo.
Now, scientifically, it seems unusual that you have an abnormal activity of alcohol dehydrogenase. In everyone there are enough enzymes to convert BDO and GHB within an 45 mins or less.
But, if you were deficient, in any way, it’d take A LOT OF TIME for it to clear your system hence the terrible hangovers from acetaldehyde buildup / same applies to alcohol, GHB and GBL.