When people are totally blown out of their minds, why they are considered psychotic, more than poisioned?

Poisioning explain very well a most of cases of psychosis. A lot of poisions have psychosis and delusion, and I am telling you poisions not drugs, as effects.

However psychiaters only test for drugs, and doesn't even thing of poision.

Like family can poision somebody, send him to psychiatry and he gets diagnosed schizo and not posioned.

Explain this one psychiatric shills.