A medical review article recently published on the nocebo effect can be found here.
What is a medical practitioner to do? Not informing a patient of potential side effects is an ethical dilemma.
The answer may lie in communication, with a focus on tolerability. In this sense, information about the frequency of adverse events can be formulated positively ('the great majority of patients tolerate this treatment very well'). An example of 'positive framing' of potential side effects resulting in increased tolerability of influenza vaccination can be found here.
The words matter.