Phentermine has been used in prescription weight management since its initial U.S. approval in 1959. Despite the development of newer weight-loss medications, it remains an option for appropriately selected patients.

What Is Phentermine?

Phentermine is an oral prescription medication that suppresses appetite. It belongs to a class of drugs called sympathomimetic amines and is classified as a Schedule IV controlled substance in the United States.

It is FDA-approved for short-term use, generally described in its labeling as 12 weeks, as an adjunct to calorie reduction, exercise, and behavioral modification in eligible patients with obesity or overweight accompanied by certain risk factors.

How Does Phentermine Work?

Phentermine acts on the central nervous system, increasing signaling involving norepinephrine, which helps reduce hunger and appetite.

For some patients, this makes it easier to consume fewer calories and follow a structured weight-management plan.

What Results Can You Expect?

Weight loss varies depending on the individual, treatment duration, nutrition, physical activity, and other factors.

Phentermine may help reduce appetite during treatment, but it does not guarantee a particular amount of weight loss or prevent weight regain after treatment ends.

It is intended to be used alongside lifestyle changes, not as a stand-alone solution. The appropriate duration of treatment should be determined by the prescribing clinician, consistent with applicable labeling and clinical considerations.

What Are the Side Effects?

Common side effects include:

● Dry mouth

● Insomnia or difficulty sleeping

● Increased heart rate

● Elevated blood pressure

● Restlessness or nervousness

● Constipation

Phentermine can also carry risks related to cardiovascular effects and misuse. Rare but serious concerns require prompt medical evaluation, particularly new chest pain, fainting, or unexplained shortness of breath.

Phentermine is contraindicated in patients with certain cardiovascular diseases, uncontrolled hypertension, hyperthyroidism, glaucoma, pregnancy, a history of drug abuse, and specific other conditions. It must not be taken during or within 14 days of monoamine oxidase inhibitor use.

A clinician should review your medical history and medications before prescribing it. Do not combine it with other weight-loss medications unless specifically directed by an appropriately qualified clinician.

Who May Be a Candidate?

Phentermine may be considered for eligible patients with a BMI of 30 or greater, or 27 or greater with certain weight-related health conditions.

It may be an option for patients seeking an oral appetite suppressant, provided their medical history and risk factors support its use.

Because phentermine is a stimulant-like medication with important precautions, it is not suitable for everyone.

Is Phentermine Right for You?

Phentermine has a long history in weight management, but its age and familiarity do not make it the right choice for every patient. Newer medications offer different mechanisms of action and treatment options.

At New Beginnings Plastic & Reconstructive Surgery, our SlimTonic program helps patients explore medically appropriate weight-management options based on their individual needs.

Learn more about SlimTonic and the range of treatment options available through a medically guided weight-management approach.

Medical disclaimer: This article is for educational purposes only and is not a substitute for individualized medical advice. Phentermine is a prescription medication with important contraindications and potential side effects. It should be used only under appropriate medical supervision.

Medical reference: DailyMed: Phentermine hydrochloride prescribing information.