The non-psychoactive iso-LSD is produced during the manufacture of LSD and/or during prolonged storage under non-destructive conditions (exclusion of light and oxygen); in each case by so-called isomerization.
Some users report that iso-LSD inhibits and/or otherwise influences the effects of LSD. However, there is as yet no scientific evidence to support this hypothesis. Whether iso-LSD can produce non-psychoactive but otherwise pharmacologically relevant effects has not been conclusively clarified. Especially in higher doses, pharmacologically significant effects are conceivable.