You know, I only mentioned that I gave a capsule to Hotarubi. The Vile Vials..... well.....
*Evil smile*
You're free to throw up all you want.

The human metabolsim includes the speed at which substances move through your system. For example, neurotoxins move through the blood, and once they reach the heart, the victim dies. Many venoms also have an incubation period, where they have to spread, be digested, be absorbed into the blood..... as such, most do not instantly take effect.