check the instruction leaflet that comes with the injection if you dont have it ask the nurse or who ever gives you the injection it will be in small print...
Kirki, Please check with your Dr immediately. I had heard before that St Johns Wort interacts with contraception methods. I have googled and found a website www.contraceptiononline.org that advises that both Sweden & Britain have issued warnings regarding taking St Johns Wort while using contraception. Hope this helps.