Well... it's at least worth a try :
- Right-click on her portrait on the right sidebar so you get her radial menu.
- Select the icon at... 10 o'clock, I think.
- In the new radial menu that comes up, select the icon at 3 o'clock
- Her inventory should come up
- Call up your own inventory
- pray...
If that didn't work... I'm not sure... you can drag&drop potions right onto your henchman, maybe one can do the same with normal items too?
-Zel