Using healing serum on my character

I made the serum, I keep it handy, but nothing I do enables me to use it. I've tried T, G, etc. Changing assigned keys, etc. Nothing. ARGH. I am playing on PC. Please help?

Community Manager

You need to have less than full health to be able to use the healing serum, is this the case?

Hi, Yes I am near empty on health. Thank you.

Community Manager

Have you managed to use it before, or is it impossible to use at all?

Looks like your connection to Focus Home Interactive - Official Forums was lost, please wait while we try to reconnect.