Drug safety (Pharmacovigilance) includes:
- Collection of information on drug safety
- Scientific evaluation of this information and identification of safety signals
- Evaluation of the risk-benefit ratio of drugs
- Distribution of information related to drug safety
- Safe-guarding public health and taking necessary actions

The safety and the efficacy of drugs are determined during the development Phase. The information on drug safety from clinical studies is, however, limited because the treatment time in studies is usually short and the number of patients exposed to the drug is relatively small and the patient population carefully selected. Due to this rare adverse effects e.g. or those related to long-term treatment may not be detected.

Once the drug has been approved and is available from thousands to millions of patients the pharmaceutical company gets new information on its adverse effects and the understanding of the safety profile of the drug increases successively. Safety information is received e.g. from healthcare professionals reporting adverse effects and from post-authorization safety studies. The marketing authorization holders have a legal obligation to have pharmacovigilance procedures in place and to continuously monitor the safety of their products. Evaluation of adverse drug reaction reports, forwarding relevant reports to authorities, continuous risk-benefit assessment and risk minimisation are examples of these procedures. A risk management plan is required for new drugs when a marketing authorization is applied for so that possible risks are identified as early as possible after the introduction of a new drug on the market.

The pharmacovigilance responsibilities of pharmaceutical companies apply to all products during their entire lifecycle up until the marketing authorization is terminated.