Having no idea which are the 25 items to use to qualify? Here's the list.
There are more than 25 of them actually and I achieved it without having the DLC.

Some suggestions:
a. you can either do it along with other achievements or attack it specifically.
b. play on easiest level so that you are not focused on staying alive but consuming the items.
c. equip and consume the item as soon as you have it, in the next combat round. Except for revealer which is in Moment In Madness, you need to specifically use it in the laboratory.
d. list of items & which scenario you can find them:

abbrevaion of scenario:
hard times -HT
as good as dead - AGAD
in gold we trust - IGWT
graveyard shift - GS
method in madness - MIM
law & order - LO
a matter of time - MT
on earth, as it is in hell - OE



1) Coca leaves -GS,
2) Vitality elixir -IGWT
3) Mandrake powder - GS
4) Dose of opium - GS
5) Bottle of liquor - GS
6) Snuff - MIM
7) Mandrake root - AGAD
8) Ginseng - GS
9) Tobacco - GS
10) Relic - HT
11) Blood berry - Scar of Freedom (DLC)
12) Dexterity elixir - HT
13) Medical bag - IGWT
14) Shaman's pipe - MIM
15) Nail bomb - MT
16) Eagle Elixir - MT
17) Angelic sphere - GS
18) Dried meat - LO
19) Healing elixir - MT
20) Stimulant - MIM
21) Petrification bolt -AGAD
22) Noise bomb - IGWT
23) Gas bomb - MIM
24) Stun bomb - IGWT
25) Poison vial -IGWT
26) Revealer -MIM

Good luck.