Plagues and Poisons
Even the Plane of Shadow has some unique diseases and poisons, although perhaps not as many as most other planes.

Diseases:
Code:
Disease      Infection   DC  Incubation  Damage
Black Blight  Ingested   16   1 week     1d4 Str
                                         1d4 Cha
The Fading    Inhaled    18   1d4 days   1d6 Dex
Black Blight: Black blight is caught by eating some plants indigenous to the plane of shadow. The target’s hair turns black and falls out as their skin becomes pockmarked and worn. It takes three consecutive saving throws to cure yourself of black blight, rather than the normal two.
The Fading: In some less formed areas of the plane of shadow, especially near the darklands, the air is only partially formed and tries to disassemble anyone breathing it from the inside out. Every time that a creature takes damage from the fading, they must make another fortitude save or lose their sense of touch for the disease’s duration, imposing a –2 penalty on all climb, disarm device, jump, open lock, swim, and tumble checks. If they have already lose their sense of touch, they are rendered blind for the disease’s duration. If they are already numb and blind, they are rendered deaf for the disease’s duration.

Poisons:
Code:
Poison                     Type                Initial Damage          Secondary Damage                  Price
Ebon Extract               Contact DC 17       1d4 Wis                 Unconsciousness for 1 hour        425 gp     
Midnight Residue           Contact DC 22       0                       2d6 Str+2d6 Dex                   1,500 gp
Black Root Vine            Ingested DC 16      1 Dex                   1d4+1 Dex                         150 gp
Beverut                    Ingested DC 20      0                       3d6 Dex                           750 gp
Ebon Cloud                 Inhaled DC 15       1d4 Wis                 2d4 Wis+1d4 Int                   225 gp
Black Mist Powder          Inhaled DC 25       0                       -2 Will saves for 1 hour          175 gp
Shadow Scuttler venom      Injury DC 13        -10 speed for 1 hour    no running/charging for 1 hour    400 gp
Dark Ichor                 Injury DC 15        1d4 Dex                 sickened for 1 hour               200 gp