Serious and potentially life-threatening reactions ( serotonin
syndrome) can develop if
venlafaxine and non-selective, irreversible
MAOIs are given concurrently, or even sequentially if insufficient time is left in between.
The manufacturers of
venlafaxine recommend that one week should elapse between stopping the
venlafaxine and starting an MAOI, and 2 weeks between stopping an MAOI and starting
venlafaxine.