Phentermine is a prescription medication used short-term for weight loss in overweight or obese individuals. It works by suppressing appetite and increasing energy, aiding in calorie reduction and promoting weight loss. Typical dosage ranges from 15-37.5 mg daily, taken before or after breakfast. Benefits include appetite control, weight loss support, and increased energy levels. However, it should be used cautiously due to potential side effects like dry mouth and increased heart rate, and it is not suitable for long-term use or without medical supervision.