Accidentally I quick-saved the game after a fight against a swarm of cazadors. I didn't recognize that my companion, Rex, was poisoned and remained with only 41 hp. He dies after 15 seconds of savegame loading.
I have spent 15 stimpacks in order to prevent him die after quick-save loading (he dies after 15s with no stimpacks) and loading a previous savegame was not in discussion because I made more than 1 hour before.
Are other possibilities to cure companions from venom? It seems they are affected more then me by continuously damage.
Update: Forgot to say that I play on PC in hardcore mode.