Slideshows Images Quizzes
font size


Medical and Pharmacy Editor:

Brand Name: Adipex P, Lomaira

Generic Name: phentermine

Drug Class: CNS Stimulants, Anorexiants; Stimulants; Sympathomimetic

What Is Phentermine and How Does It Work?

Phentermine is a prescription medication used with a doctor-approved exercise, behavior change, and reduced-calorie diet program for weight loss. 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.

It is not known how this medication helps people to lose weight. It may work by decreasing your appetite, increasing the amount of energy used by your body, or by affecting certain parts of the brain. This medication is an appetite suppressant and belongs to a class of drugs called sympathomimetic amines.

Phentermine is available under the following different brand names:
Adipex P, and Lomaira.

Dosages of Phentermine Should Be Given As Follows:

Adult and Pediatric Dosage Forms & Strengths

Capsule, HCl salt: Schedule IV

  • 15mg (generics)
  • 30mg (generics)
  • 37.5mg (Adipex P, generics)

Tablet, HCl salt: Schedule IV

  • 8mg (Lomaira)
  • 37.5mg (Adipex P, generics)

Dosage Considerations

Discontinue if weight loss has not occurred with 4 weeks of therapy. Not approved for long-term use.

Discontinue if tolerance develops, and do not exceed recommended dosage to overcome tolerance.


Short-term (few weeks) adjunctive use as part of weight-reduction regimen based on exercise, behavioral modification, and caloric restriction in management of exogenous obesity for patients with initial body mass index (BMI) ≥30 kg/mē or ≥27 kg/mē in presence of other risk factors (e.g., controlled hypertension, diabetes, hyperlipidemia).

Adipex P or generic

  • 15-37.5 mg/day PO in single daily dose or divided q12hr before breakfast or 1-2 hr after breakfast


  • Typical dose is 8mg PO TID 30 minutes before meals
Medically Reviewed by a Doctor on 2/22/2017

Women's Health

Find out what women really need.

Use Pill Finder Find it Now See Interactions

Pill Identifier on RxList

  • quick, easy,
    pill identification

Find a Local Pharmacy

  • including 24 hour, pharmacies

Interaction Checker

  • Check potential drug interactions
Search the Medical Dictionary for Health Definitions & Medical Abbreviations

Health Solutions From Our Sponsors