Hello! Welcome and thank you for asking on HCM! Regarding your concern, I would explain that effexor is an antidepressant, which can be really effective in the prevention of migraine attacks. You should know that this drug does not show its effects in the first 2 weeks form the beginning of the therapy, but more gradually after this period. So there is nothing to worry about. These are just the first days after restarting therapy. You should just be more patient. I would recommend taking exedrine or ibuprofen for the pain during this period, to have some pain relief. Hope you will find this answer helpful! Kind regards, Dr. Aida