Effects on the human body
Sulfonal: 1 toxin damage every 2 cycles, knocks you out after 22 cycles.
Fentanyl: Will deal 1 toxin and 3 brain damage per tick, knocks the user unconscious after 36 seconds.
Mute Toxin: Makes the subject unable to speak.
Cyanide: Causes headaches and sickness at first, followed by failure of cellular respiration leading to cardiac arrest, suffocating its target.
Formaldehyde: Causes a moderate amount of Toxin damage over time. Has a chance to turn into 5 to 15 units of Histamine.
Strategy
Use in syringe to silently subdue your target, or feed increased amount to subject via pill/liquid form.
Smoke is also an option.