Health Information Library
All the content of the library is provided from Mayo Clinic in English.
As a member of the Mayo Clinic Care Network, RSPP has special access to Mayo Clinic knowledge and resources.
< Back
Phentermine for weight loss
Answer Section
Phentermine (Adipex-P, Lomaira) is a prescription medicine used to lessen appetite. It can help weight loss by making you less hungry. Or it can help you feel full longer.
Phentermine also is offered combined with topiramate for weight loss (Qsymia). The combined drug is approved for long-term use. Phentermine is approved for use for up to 12 weeks. But weight management can take time. So some health care providers might order it for longer use.
Like other weight-loss medicines ordered by providers, phentermine is meant to be only part of a weight-loss plan. For example, it can be be used with healthy eating, physical activity and behavior change. Phentermine is for people with obesity or overweight who haven't been able to lose enough weight with diet and exercise alone to improve their health.
Phentermine is a Schedule 4 drug. This is a label given to drugs that can be misused. But the rate of misuse seems to be low.
Common side effects of phentermine include:
- Faster heart rate
- Sleeplessness
- Nervousness
- Constipation
Phentermine is one of the most prescribed weight-loss medicines. But it isn't a good choice for people with heart disease, high blood pressure, an overactive thyroid gland or glaucoma. It also isn't for people who are pregnant, may become pregnant or are breastfeeding.