Weight-loss medications work in various ways to help you lose weight and maintain weight loss long term. Common classes include sympathomimetics and GLP-1 receptor agonists. Sympathomimetics, such as phentermine (Adipex-P, Lomaira) and diethylpropion, are taken as oral pills. GLP-1 receptor agonists, such as semaglutide (Wegovy) and liraglutide (Saxenda), are available as injectables. These options provide different ways to help you achieve your weight-loss goals.