Hi, Since your depression is not responding to citalopram 40 mg, you need other interventions. There are three options. The dose of citalopram can be hiked to see if it gives a better response. But this must be done with caution as you are already on a fairly high dose. Secondly, other medicines can be added to citalopram to augment its action, like thyroid hormone, lithium, a second antidepressant etc. The third thing that can be done is to switch to another antidepressant that may give better results. Venlafaxine would be a good choice in my opinion. Please discuss with your doctor the option that would suit you best and do accordingly. Hope you get better soon. Best wishes.