"i take 300 mg effexor am and 15 mg mirtazapine pm just before i go to sleep. this combination has worked very well for me and the only side effect i really have is a bit of dry mouth but that&#039;s probably exacerbated by smoking. for me, they counteract each others side effects at these dosages cause at 225mg effexor and 30mg mirtazapine i had an insatiable appetite at night time!"