I was on Effexor XR for over a year and during that time I missed a few doses...those days were the worst. I remember I felt so sick one day and was thinking of not going anywhere, I had such a bad headache and had aches and pains and felt really depressed. I had no idea what caused this, a little while later I remembered that I had forgotten to take my medication, I took it and I felt fine again.

If you are going to quit Effexor make sure you get weaned off of it. I made the mistake of going cold turkey when I was taking 150 mg daily I think, and it was pretty bad. The bad withdrawal lasted about 2-3 weeks then I was fine for the most part after that.