An illness that appears abruptly after using/reusing previously used or contaminated cotton filters in the preparation of intravenous drugs. Someone who does IV drugs needs to filter the solution with a cotton to take out the particulate matter, and a small piece of cotton rolled up into a ball is often used as a filter when the drug solution in initially drawn up into the syringe.

Contrary to popular belief and junkie myth, cotton fever is not the result of accidentally injecting small cotton fibers into your blood, but is actually caused by an endotoxin from the bacteria Enterobacter agglomerans that can reside in picked cotton. The toxin is disolved into the drug solution, and when the injector injects the drug, the toxin causes an immediate and severe flu-and-fever like illness that can last anywhere from several hours to a day or two.

Cotton fever may also be caused by the reuse of previously used cotton filters. The filter, after its first use, is a moist breeding ground for bacteria and fungi, all of which can be accidentally injected and result in illness if the cotton is reused.
John was real sick with cotton fever on Wedesday... First his muscles all tensed up and he felt nauseous. He started to sweat, and he felt like he was boiling hot. He got a really bad fever, and starting having muscle aches and cold chills. All this happened in the span of about 2 minutes... John just slept it off for six hours, woke up, fixed a clean shot, and felt better.
by Exo-skin January 8, 2011
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When you use your left over cottons from shooting heroin to try and get high again, but the result is that you accidentally inject cotton which will cause your body to feel sick and feverish.
I tried shooting one of my cottons today but it only made me sick,i must have cotton fever, my bones ached!
by john213123 January 16, 2008
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