Do I need to use a new needle everytime I inject HCG? Or can I just mix 2ml of water with 2000IU of HCG and use the same needle to inject 4x0.5ml then put the needle back in the fridge?
I don't see any reason why not -- it's pretty safe if you're careful not to contaminate the needle. With HGH, I draw up all of the solution in a 1cc insulin syringe, take 0.1 cc at a time, & keep in fridge in between. Only problem is the needle keeps getting duller.
If you inject once, you have contaminated the needle. You'll likely be fine, but why take the risk? Transfer the solution to 4 insulin syringes, costing you about 60 cents more.
Anyway, I've been doing the multi-dose thing I described for years without ever getting infected.
So while I definitely agree that you shouldn't ever reuse a needle for an IM injection, I wouldn't worry about it with subQ. And of course, NEVER use a needle someone else has used.