The big pharma doses of Wegovy are .5mL except for the 1.7mg and 2.4mg doses which are .75mL (All Mounjaro/Zepbound doses are .5mL FWIW). Ozempic the lowest dose is .375mL and but the rest are .75mL.
When I started on tirzepatide, I stuck with the .5mL volume as my target since that's what the manufacturer was using and never had a single ISR or any other issue. At some point when I started buying vials with higher content I dropped it down to anywhere from .25mL to .4mL depending on how much was in the vial and what my dose was.
I never had an ISR with less volume, however I did tend to find the injection location to be a tad more tender for the rest of the day compared to higher volumes. Fortunately I never experienced any welts, itchiness or other ISR's that some people do.
Ultimately it's a personal choice, but I tell most people to shoot for something in the .25mL to .5mL range, really whatever is going to work out most conveniently for the contents of the vial in relation to dose and keeping the math as simple as possible. The thing I do try to point out is that more fluid generally results in more accurate dosing since it's easier to measure and draw from the vial, and more forgiving if you lose a couple of drops or have any left behind in the syringe.
