Can one really get ill by worrying too much?
To answer this question, we have to start to explain what a placebo is, and after that to define what negative placebo effect is.
Wikipedia defines placebo as follow:
“A placebo is an inert substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures.” [...]