I had cotton fever on a few occasions, it is def. from dirt or bacteria getting into your drug ur shooting, from dumping heroin on the table, and scooping it up and dumping in a spoon, dirt collects with it, being a reason, or using old cottons that are not sealed up and dust and bacteria getting onto it over time...I remember I IVed a piece of subutex, and 10mins later just felt funny, I knew cotton fever was coming on and it hit me 20mins larer, it got so scary, my muscle and bones were aching, head and eyes were aching and pounding, my heart was pounding so fast I thought I was gonna have a heart attack, I got scared and thought about all the dangers of shooting pills, I got soo cold and shaky I wrapped up in 3 blankets when It was a hot summer day and fell asleep shaking. I had it a few other times, I was shooting crack, and got it, and me any my cousin thought I was going to have a heart attack from the crack, so she kept giving me Xanax, and it still didn't work, so her friend an ex paramedic said u must NOT let ur body make u wanna lay down, u need to fight it and drink water, lots of it..which I did and felt better..its not a fun experience..im very cautious now. I use alcohol wipes that the needle exchange gives u and I clean my cap, use a brand new needle, and sanitize my hands. and make sure im not just using an id card and scraping coke or heroin off a table and into the cooker cap. always wash your hands and us fresh needles, and get proper cottons at ur nearest needle exchange. they have silver caps (cookers) looks like the cap of a liquor bottle, or small gold ones, bag of cotton balls(I told the lady that worked there that I heard micron filters were safe and cottons are not, she told me the cotton balls they have are made specifically where they are really compacted) if all else fails, use cotton off the ear swabs. They have small bottles of bleach, blue tubes of fresh water sealed, alcohol wipes, sanitizing wipes for your hands...Needles from half cc to 1 cc standards, 27-31 gauges to choose, 2 cc (2ml ?) needles much bigger too. you can also take a 15min class to get a supply of naloxone injections to take with you, and a needle card to legally possess needles, its ridiculous u can buy needles at ride aide but its a class A Misd if caught . even if clean. be safe and be clean before shooting up..never miss a vein!!! I missed shooting in my foot and had an abcess so big that was infected, when I finally went to the hospital, after all was done, the hole went from my ankle bone to the other side where the ankle bone is, they packed it with gauze, this was VERY painful, had to be admitted for 3 days..they were debating plastic surgery ,and amputation of foot it I waited another 3-5 days..its no joke...