I am on effexor (venlafaxine) and I can tell you missing even one dose is EXTREMELY not wise. Thanks to the VA, I went 3 days without it and it was hell. After about 16 hrs, you start seeing and hearing things that aren't there. After 24 hrs, you get VERY anxious, can't sleep, nausea, etc. These were my experiences. I have PTSD, so I'm hyper-alert already and anxious. Being without the medication, it amplified these things 20-30 times worse. If you don't want to go somewhere for the holidays, be honest....tell the person/persons you would rather not come. Above all, I would advise you not to skip doses.