Abstract: A fluid projectile launcher (10) comprises a barrel having an open end and a closed end defining a breech portion (50). The breech portion (50) is arranged to hold a dosage of fluid (56) in the form of an ionizing medium for rendering the fluid electrically conductive and an active substance which induces a physiological reaction in living organisms. The projectile launcher (10) includes a launching initiation circuit in the form of a capacitor (22) and an inductance (36), and a pair of electrodes (38A, 38B) forming part of the breech portion (50). Trigger means (40) are provided for allowing the energy storage means (22) to discharge into the dosage of fluid (56) in the breech portion (50) via the electrodes (52, 38A, 38B) so as to cause the dosage of fluid (56) to be projected from the open end of the barrel as a fluid projectile.