Phentermine Patient Information

Who Is Phentermine For?

Phentermine is a medication for weight management. It is for people with overweight and weight-related complications or obesity. It is meant to be used together with a lifestyle therapy regimen involving a reduced calorie diet and increased physical activity.

How Does Phentermine Work?

Phentermine is an appetite suppressant that works in the brain.

Who Should Not Take Phentermine?

  • People who have heart disease or uncontrolled hypertension

  • Women who are pregnant, nursing, or planning to become pregnant

  • People who have glaucoma

  • People with uncontrolled hyperthyroidism (overactive thyroid)

  • People who are taking a monoamine oxidase inhibitor (MAOI) now or have taken one

    within the past 14 days

  • People who are prone to agitation (extreme restlessness and irritability)

  • People with a history of drug abuse

 

How Is Phentermine Dosed?

Take 1 tablet or capsule once a day before breakfast or 1-2 hours after breakfast.

Phentermine is approved for short-term weight loss therapy. The usual duration of treatment is 12 weeks or less.

Is Phentermine a Controlled Substance?

Yes, phentermine is a federally controlled substance because it may be abused or lead to drug dependence. Some states only allow your doctor to prescribe one month at a time.

Which Medications Might Not Be Safe to Use with Phentermine?

Phentermine can affect how other medicines work in your body, and other medicines can affect how phentermine works or make side effects worse. Tell your doctor about all the medicines and supplements you take (ask your doctor or pharmacist for a list if you’re not sure), especially the following medicines:

  • Monoamine oxidase inhibitors (MAOIs)—usually used to treat depression

  • Adrenergic neuron blocking drugs—these are usually taken to treat high blood

    pressure or psychotic symptoms

  • Other weight loss medications, including over the counter medications

What Are the Common Side Effects of Phentermine?

  • Dry mouth

  • Restlessness

  • Difficulty sleeping

  • Increase in heart rate

  • Increase in blood pressure

  • Constipation or diarrhea

 

What Are the Possible Serious Side Effects of Phentermine?

Primary Pulmonary Hypertension

A rare but often fatal disease of the lungs known as primary pulmonary hypertension has been reported in patients taking phentermine and phentermine-like products. Stop taking phentermine and call your doctor if you experience any difficulty breathing, severe chest pain, fainting, or swelling in the legs.

Heart Valve Disease

Serious heart valve problems or disease have been reported in patients taking phentermine or other phentermine-like products for weight loss. The possibility of an association cannot be ruled out.

Low Blood Sugar (Hypoglycemia)

Weight loss can cause low blood sugar in people with type 2 diabetes who also take medicines used to treat type 2 diabetes. Test your blood sugar before and during treatment with phentermine.