I took vermox, its the drug that kills worms so I took two a day for three day. How long does it stay in your system as I have terrible side effects.

1/2 life 6 hours. The half life is short, 3-6 hrs. It should be largely cleared 1-2 days.
Vermox. Vermox is not longer available in the US for that purpose. If you have terrible side effects, try something different, talk to your doctor, there are other choices. You won't be able to get Vermox any longer.