Medroxyprogesterone
"Literal life saver. I have heart issues, so birth control doesn't work well for me as it causes arrhythmia and palpitations. It took me years to get a doc to give me something other than birth control. When I started provera, I had 10mm of lining built up in my uterus and obgyn said it was a matter of time before I got cancer had I kept going without periods.
Now, sometimes my periods come on their own. When they don't, I take provera for a few days and it seems to kick start things again. 
Worst side effect is if I take the first dosage they had me started out with for the 10 days, around day 5 I start getting horrific nightmares. Lowered the dose and days taken and it still works minus the nightmares. No problems with my heart or bp."