Vicodin has both Tylenol and another pain killer, right? I can't take a Vicodin without the following symptoms: sudden high blood pressure, irregular heart beat, spasticity.
I thought this was because I had Porphyria, and Vicodin is a no-no for that. But it may be that others get these symptoms.
When I was in hospital for a back injury, they wanted to transfer me to a nursing home, and insisted I take Vicodin. I told them what would happen. They said try one pill. I did, got the symptoms, and I had them write down and document the High blood pressure and irregular heart beat. I imagine it didn't change their habits to see what one Vicodin could do to a susceptible person.

I had the HBP and irregular pulse still when I got to the Nursing Home by ambulance, but both went away shortly after that. They then gave me Demerol or something in that category, which did not cause side effects. What one must do to prove things sometimes.