An "Adverse Effect" refers to any harmful or unintended consequence that arises from a treatment, medication, or intervention. These effects can range from mild symptoms, such as nausea or headaches, to severe reactions that may require medical attention. Understanding adverse effects is crucial for evaluating the safety and effectiveness of various therapies. In the context of pharmaceuticals, drugs are often tested in clinical trials to identify potential adverse effects before they are approved for public use. Regulatory agencies, like the FDA, monitor these effects even after a drug is on the market, ensuring that any new information is communicated to healthcare providers and patients.