Side effect 1 refers to an unintended reaction that can occur when taking a medication or undergoing a treatment. These reactions can vary in severity and may affect different individuals in unique ways. Common examples include mild symptoms like headaches or nausea, which can often resolve on their own. In some cases, side effect 1 may lead to more serious health concerns, requiring medical attention. It is important for patients to discuss potential side effects with their healthcare provider before starting any new medication, ensuring they are informed about what to expect and how to manage any adverse reactions.