I was switched from 150mg effexor (venlafaxine) to 50mg valdoxan directly 4 weeks ago. i now notice irritability and anger. is this withdrawal or depression?

hard to know: Your best choice is to discuss this carefully with your treating physician. This medicine is available for treatment of depression in europe and australia, but not in the us, so I have no personal professional experience with it. That being said, it may be withdrawal, as this is the time frame when the effects of Effexor (venlafaxine) tend to be fully worn off. Another medication may be indicated.

hard to say but...: Effexor (venlafaxine) is notorious for causing bad withdrawal symptoms of which irritability could be one. You might suspect depression if other symptoms of depression are present such as loss of interest in pleausurable activities, decreased appetite and energy, poor sleep, guilty feelings, poor concentration. Definitely talk with your health care provider.