Hey, I didn't complain when I got this super rare blood cancer that caused me to have a heart attack last August AND I didn't complain when it caused 2 mini strokes a few months later BUT now it has made me anemic, and I have to take B12 shots to give me energy and those shots have given me cystic acne SO now I AM complaining because I am 64-years-old and nobody should have to deal with giant, painful pimples AND wrinkles at the same time, LOL Somebody, please give me a treatment plan for cystic acne that uses salicylic, instead of benzoyl peroxide; it's supposed to be gentler on elderly skin. 
Thanks, Purple Melanie
I can confirm that B12 injections do cause cystic acne. Perhaps because B12 is made by bacteria and bacteria causes acne, but moreso because it's just a large dose of something foreign to your body.
Living with cystic acne is basically like being in an abusive relationship: one false move and it's over for you. You have to eat vegan, low sugar (sugar okay, but no sugar binges), sweat regularly - cardio or sauna, frequent peeling and exfoliation, keep immune system high, and no complicated make up or products.
Hope this helps! I just had a cystic outbreak from severe air pollution + low immune system. It's soul destroying.