300mg>150mg

I took effexor 150mg for about 6 months then I relapsed due to a personal situation. My dose was increased to 300mg and I was put on seroquel and lithium alongside it.

I came out of the episode I’m in a good place now but my urge to drink has increased so doc advised to switch back to 150 (I took 300 for full 4 months) is it a huge drop???