Hey Morphoid,
I know exactly what you mean. I started IVing ages ago, and managed to keep it to occasional use, but for various reasons got a lot more into it earlier in the year and I developed an insane needle fixation. I was shooting water and doing some very unsafe things.. I was dreaming about IVing and thinking about it constantly. My veins were becoming very damaged and I had tracks all over my hands, and I was doing it secretly for a while so I would spend days and days sat alone in my flat, not eating or otherwise looking after myself. I really thought there would be no way back from it, but I've not picked up a needle in a few months now and I can honestly say I do not feel tempted, I don't dream about it, and I've even been able to sit around with others who are shooting and not shoot myself
For me, it took a few things to get me to stop.. one was a realisation that if I carried on I would be dead or do myself some serious damage. This alone didn't stop me however as I didn't care about myself enough to be hugely bothered, and I was too hooked

The second thing was having a good friend who didn't judge me (he'd been there himself) but who wasn't afraid to tell me in no uncertain terms that I had to stop or I'd seriously fuck myself up. We fought about it a few times, but his brutal honesty did start to sink in and he helped me hugely. The third was when I decided to try to look after myself more - I didn't care about myself at all while I was shooting up all the time, so I decided try pretending that I did and making an effort to be healthy and kind to myself for a week, to see if it helped. I ate properly, washed myself, got out the flat, gave myself (non-drug) treats and generally tried to do things that would make me feel better. I had zero hope for it working, but it actually did, slowly

I started to feel better about myself, and as I did I started to actually want to stop IVing, and believe that I could. The better I got, the stronger my drive was to quit, and the more I took care of myself the easier it was to contemplate a life without the needle.
Making the final jump away from it was really hard and I had a few false starts (do not beat yourself up if this happens, just keep trying..). Drug counselling could really help I think, but this wasn't an option for me unfortunately so I made sure I kept talking to my friend and was honest about it all with him. Plugging can be a good way of moving away from injecting but still retaining some of the prep etc but I wanted to break the cycle completely so I didn't really try this - I stopped dead, rid my flat of IV paraphenalia, broke the needles rather than just throw them out (so they couldn't be retrieved by me later

), told people not to sell me drugs, and went to stay with my parents for a bit. As I said, I did relapse a few times

and for a while I didn't think the cravings would ever go away, but the really have. Now when I think of it I think of the damage I was doing, and the dark place I was in, and I never want to go back there. I still do think about it of course, and wish I still could do it from time to time, but the burning desire has definitely gone.
These are things that helped me:
Finding someone you can be entirely honest with, who won't judge you but will most definitely not enable or encourage you to continue (or use us here

. Look into drugs counselling perhaps, how do you feel about that? Have you had it already, if you're on bupe maintenance? Is there anything specific in your area for helping people break a needle fixation?
Keeping yourself busy is really important - try to find activities you enjoy; of course you won't enjoy them as much as IVing initially, but it's better to be sat not IVing while you do something else fun than sat there twiddling your thumbs trying to fight the urges. Get really stuck into your degree maybe? That could have a really positive benefit on your self esteem and general wellbeing too
Rid yourself of your IV equipment - properly! I half-heartedly threw mine away so many times..
Make sure you are taking good care of yourself too

eat properly, wash/dress/make an effort, be kind to yourself.. treat yourself to nice things - bubble bath, tasty food, fave film/book etc, whatever floats your boat
Write down all the cons of IVing (serious risk to health, tracks, risk of OD, ruin your career at med school/ a doctor, distance from friends/family, low self worth, money etc) and try to spend some time thinking about those whenever you get the urge. Conversely, write down all the positives to stopping and reward yourself every time you manage to resist temptation. Marking landmarks helped me too - day 1, week 1, month 1 etc..
Don't beat yourself up if you do relapse, but don't stop trying
Good luck - it is definitely possible to beat this
