I used to shoot Ritalin, mostly ER20mg pills. Mostly we shot them one at a time, occasionally 5 or even 10. I began by not filtering them, like the people I learned from, but one day I watched a rig of liquid stuff begin to cool off inside the syringe and 2/3 or it turned back into powder. That freaked me out so I at least began filtering it. I heard from other Ritalin slammers that the powder remains inside your body, and is most fond of the blood vessels in your lungs, your liver, and behind your eyes. I know one guy who lost his sight in one eye when the capillaries behind his eyes sclerosed.
I had a pulmonary event at one point where it became very difficult to breathe and I went to the ER. I don't remember it all that well; mostly just that I was starting to turn blue with hypoxia, they got me into the ER and did some kind of treatment--I don't really know exactly what they did, ran some kind of drugs through my IV and gave me some treatments with a nebulizer. Then this doctor said "I know it won't do any good to tell you to stop shooting Ritalin, but if you don't filter them better you're going to die." I hadn't told him anything about shooting Ritalin--I had tracks but it was in the day when if you saw tracks you assumed heroin, which was my DOC, only I was on the methadone clinic, hence the Ritalin. So I assume that he knew from something that they found inside me or the way it showed up on an X-ray.
Fast forward about 40 years, till just a few years ago. I'd had pulmonary issues off and on for a number of years, but I almost died in the ER about three years ago when I went in completely unable to breathe. Turned out I had COPD, with emphysema (mostly from smoking, which I'd done for almost 50 years at the time) and pulmonary fibrosis, although they didn't know what was causing that. Since I didn't volunteer the information that I'd shot Ritalin or several years, they still don't know why I have it, and there's nothing that can be done; it's a fatal lung disease that, with the emphysema, will eventually kill me and has already crippled me. I'm oxygen-dependent 24/7, take a bunch of different steroids and other inhaled drugs that have side effects, mostly nasty, etc.
I don't blame anyone for my condition, since I made the choices to stick needles into my arms, to smoke, and all the rest. I just didn't figured I'd live long enough for it all to catch up with me. BTW, I've been in recovery off and on since 1989 and consistently for the past 8 years. Just got an 8 year coin last week. And am now tobacco-free as well, for 3 years. So the sad truth is that, if you live long enough, the shit you put your body through WILL get you. Please stop shooting unfiltered pills, dude--that is so bad for your body in so many different ways, and even though it may seem so at the time, all you're adding to your shot is an inert powder. It doesn't add any more active ingredient, and all that powder does collect in unlikely places where it's not going to be excreted.