When evidence emerges on rare but potentially dangerous drug effects, the Committee on Safety of Medicines needs to act to protect the public. On the basis of clinical experience after guidelines relating to thioridazine were revised, Davies and colleagues argue that directives should take greater account of the risks associated with changing successfully established drug regimens, especially in vulnerable populations such as people with learning disabilities

When new evidence is unearthed of rare but dangerous side effects of drugs used in current practice, agencies such as the Committee on Safety of Medicines need to review and rewrite prescription guidelines. When new guidelines restrict the use of a commonly prescribed agent to a limited range of circumstances, doctors may be left in a dilemma. Patients who do not meet the criteria for continuing with a drug under revised guidelines, but who benefit from using it, may have to be exposed to the adverse consequences of changing their drugs. Influenced by the current culture of defensive medical practice, clinicians may be reluctant to continue prescribing drugs when guidelines state that the balance of risks and benefits is unfavourable in circumstances that apply to their patient. We present examples from our practice of the consequences of discontinuing established drugs in line with the Committee on Safety of Medicines' advice.