Williamson has stated her support for the necessity and value of vaccinations and antidepressants, but has been criticized for her skepticism about the pharmaceutical industry's influence in setting guidelines for how they are administered, citing her belief that their profit motive could result in harm to patients. She has also been scrutinized for criticizing overprescription of antidepressants, questioning whether antidepressants play a role in suicide, saying that the prescriptive definition between sadness and clinical depression is "artificial," and having called the process by which clinical depression is diagnosed "a scam."