Patients told the side effects of a placebo in a medical trial are highly likely to experience them, even though the placebo is an inert substance.
If you Google or Wiki 'Nocebo' or 'Nocebo effect' it will say:
Mental states such as beliefs and expectations can strongly influence the outcome of disease, the experience of pain, and even success of surgery.
When experiencing anxiety and stress-related symptoms, it could be worth factoring in the nocebo and placebo effects.
The power of your belief is immeasurable.