is possible to be triggered psychosomatically
the pre-disposition of the bodys immune system is pre-disposed to assign reactive process to coded data.
exactly how and why is quite a scientific mystery which is being studied by many specialists all over the world.
things like the poison response & placebo effect combined with minor unknown allergic responses and mechanisms can trigger fatal conditions.
e.g
shock can kill
shock kills thousands of people
do some reading on allergys
seek out and read publicly posted statements and reports and studys by
doctors, professors, patients, societys etc...
your question is very juvenile in its composition
like a child asking why a person dies when they get in a car crash.
you need to increase your base knowledge before you gain the intellectual ability to comprehend the question you are asking.
only until then will you be vaguely situated to accommodate the highly complex answer.