What’s the worst reaction you ever have had consuming food, vaccine, medicine and or a drug?

In 2000, a bad doctor gave a Haldol shot with nothing for side effects, so I suffered badly for days til a neighbor downstairs tells me I probably need Cogentin. So I went to ER got Cogentin and an hour later I was fine.. It caused large amounts of saliva to form was disgusting, and felt like my brain was turning sideways. Beware! Bad doctors are all around us! Never should have been given Haldol I found out later, and especially not without Cogentin.. and it took a downstairs neighbor to help me.