Lorcaserin is used with a doctor-approved exercise, behavior change, and reduced-calorie diet program to help you lose weight. It is used by certain overweight people, such as those who are obese or have weight-related medical problems. Losing weight and keeping it off can lessen the many health risks that come with obesity, including heart disease, diabetes, high blood pressure, and a shorter life. Lorcaserin belongs to a class of drugs known as serotonin receptor agonists. It is thought to work by affecting a certain part of the brain that helps control your appetite.