Could anyone help me? I'm on day 5 of taking champix, the side effects I have are , feeling tired, sick and headaches. The worst one for me is the headaches, I have had a headache for 3 days now. Whenever I bend over to pick something up, about 5 seconds after getting up I'm in agony! feels like I have been hit with a bat and this lasts for about 10 seconds. I also get the same thing after getting up from sitting down. Has anybody had these side effects? and how long do they last? I don't want to give up giving up, but I can't take this pain much longer.