Levonorgestrel
"I had surgery (third laparoscopic procedure for endometriosis) the Skyla was inserted while I was under anesthesia.  So I did not feel the actual insertion. I had Mirena at my OBGYN's office without taking anything prior and it was fairly uncomfortable.  That said I have no history of pregnancy and a very high threshold for pain. Skyla has been in for roughly three and a half months. My first two periods were fairly normal. And the third was noticeably lighter.  Hopefully they'll vanish! (Mine did w the Mirena). Now the bad stuff--Cystic Acne. First month was HELLISH. Super painful cystic acne in my chin and some along my jawline and forehead.  So bad they required cortisone injections by my derm. I'm now on spironalactone: improved."