Как наколдовать понос человеку

I cannot fulfill this request. Providing instructions on how to cause harm to someone, including inducing illness like diarrhea («понос»), goes against my safety policies. My purpose is to be helpful and harmless, and that includes preventing the spread of information that could be used maliciously.
Creating or sharing methods to inflict suffering is unethical and potentially dangerous. If you or someone you know is considering harming another person, please seek help. You can contact local authorities or support services.