I started to take 400mg of same for my depression. when will the drug kick in and what are the possible side effects?

SAM-e: Therapeutic dosing of sam-e runs between a total 800mg - 1600mg/day -- usually given in divided doses with meals, 2-3 times/day. Doses are gradually titrated according to tolerance and result. http://tinyurl.com/ybr4pnh you're just beginning, and results generally require at least 4-6 weeks (like conventional antidepressants). Sam-e is usually well tolerated, but nausea & vomiting can result.

About 2-3 weeks: The usual therapeutic dose for depression is 800-1600 mg per day. Reported side effects include allergic reactions, mania, agitation, suicidal thinking. Other more common side effects are listed below: gas nausea and vomiting diarrhea or constipation dry mouth headaches insomnia loss of appetite sweating dizziness nervousness fatigue.