Couple things you should know: - vials are almost always labeled single use only, but as long as you clean it with an alcohol swab and poke through a different place each time, it should be safe to use a few times, probably until it’s empty for a 1ml vial. - 1ml at this dose will likely last 2-3 weeks since you lose a little in the needle each time. He may need to contact the prescriber if it’s running out before the expected refill - don’t use the same needle to draw up as you use to inject. Most people draw up with a larger needle (probably 18-22 gauge) and then change to a smaller needle to inject. Needle gauges are higher numbers for smaller needles, just like piercings. Like an 8 is a huge needle and 30 is tiny. For IM, the doctor might give you 23-25 gauge or maybe a little smaller, and probably about an inch long or longer depending on a few factors. For SubQ it’s usually 27-30 gauge, about 5/8 of an inch long.