Phentermine starts to work within about 3 to 4.4 hours after taking a dose, reaching its peak concentration in the bloodstream in that time. However, it usually takes a few weeks before weight loss results become noticeable. The drug works by suppressing appetite and increasing energy, which helps with calorie burning. To maximize results, it should be used alongside a reduced- calorie diet and regular exercise. Phentermine is typically prescribed for short-term use, usually up to 12 weeks, though some evidence supports longer use under supervision. In summary:
- Phentermine effects begin within 3 to 4.4 hours.
- Noticeable weight loss typically takes a few weeks.
- Best results come with diet and exercise.
- Common treatment duration is 3 to 12 weeks.
This information is consistent across medical sources and weight loss guides.
