already posted this on another one related to depo but here's a link to some negative side effects.

http://www.abcinternetmarketing.com/depo-provera/

Hi!

I am in a similar boat as you. I took the depo provera injection for almost 2 years, I started when I was 15. My last injection was in october 2013. I never had any acne previous to this injection, and i got it to stop my painful periods. After a few months of being on the depo shot, I started to get what appeared to be cystic acne on my forehead only. After a few weeks, these would come to the surface, and if I popped them (which I foolishly used to) they would let out hard white puss or clear liquid. Now that I haven't been on the injection for almost 10 months, I would assume it should be gone by now but I also hear that it can take up 18 months for the injection to be completely out of your system, and my periods are nowhere near normal/regular yet. So I hope that with patience this will go away, I've tried benzac cream to no avail. I take very good care of my skin and I'm a very health concience person, so this can only be due to the depo shot. I don't know what to do now, I am considering seeing a dermatologist about it. I've been prescribed Diane 35 by my doctor, but after reading up about the horror stories (more bad than good) I think I'll pass. I don't know if injecting my body with more hormones will fix the inbalance caused by the depo or make it worse, and I don't want to be dependent on bc forever. For someone who has always had clear skin up until this nightmare of an injection, it is very traumatizing. I seriously hope your acne clears up and that you find a solution!