Cantharides

TL0, $14/dose. LC1.
Cantharides, also known as “Conquistan fly” (actually a beetle, Lytta vesicatoria), this can be used as a digestive agent or a contact agent (though as it is in a powdered form, cannot be put on blades).

• As a digestive agent, it has a one-hour delay and a HT roll to resist, and inflicts 4d toxic damage with symptoms of nausea (p. B428).
• As a contact agent, it has no delay but still allows a HT roll to resist; it deals 2d toxic damage and irritates the skin, causing blistering and moderate pain (p. B428).
  In either case, a victim who reaches 0 HP suffers convulsions; treat as a seizure (p. B429).

Source: GURPS 4th - Low-Tech, page 131