well you can try it once if he is very undernourished and see what happens. this is an emergency vitamin liquid for reptiles and should only be used sparingly to keep them from dying. I had to use it for my cham because I had no choice. chams are more sensitive to stress than frogs and it broke my heart to force feed her but it was either that or watch my cham die without at least knowing that I tried. It is a quick process and will stress them out but sometimes this is what you have to do to get them the nutrients they need if they refuse to eat. I used a medical syringe that had a very small tip so that I can gently ease it in without having to open the mouth completely.
Just a heads up, you will need some sort of measuring plate because the measurements have to be precise. (at least that is how the rescue cal was like)

Repta-Aid Critical Care Formula from Fluker's&reg - Supplements & Medications - Reptile - PetSmart