Abstract
Post-market pharmaceutical surveillance or ‘pharmacovigilance’ relies on the reporting of suspected
adverse drug reactions to regulatory databases. Recently, more ‘active’ methods that directly involve
patients in identifying and reporting suspected adverse drug reactions have been suggested. This is
different than traditional ‘passive’ methods, e.g., using databases without contacting patients directly.
Though there are benefits to active pharmacovigilance, it is not without its potential risks. Here I
highlight one of those risks – the nocebo effect. Nocebo effects are harms that are thought to arise by
conditioning or negative expectation. If a patient engaged in active pharmacovigilance is improperly
motivated to seek out and report suspected adverse drug reactions, nocebo harms can occur. Not only
is this a bioethical concern about harm, but it is also an epistemic or data-quality problem. Since
nocebo effects are not due to the pharmacological properties of the drugs under investigation, nocebo
effects reported as suspected adverse drug reactions constitute false positives in these databases.