What Are The Uses And Side Effects Of Norethisterone 5mg Tablet?

hi i ahve been prescribed norethisteron 5mg tablets to regulate my periods. i have been take them for over 5 years now. i have a congenital heart condition and the dr said that i am not suitable to take contreceptive pills as they can clot your blood which is why i have been prescribed these and i take 1 a day. i am also in a relationship in which we do have sex. what i wanted to know was that these tablets are they in a form of contrecptive pills aswell?because i was thnking that as my periods have been regular from the time i started these tablets, i was thinking of coming of them. could you please give me some advise.thank you