What Is Phendimetrazine? Uses, Dosage, and What You Need to Know in 2026

Phendimetrazine is a prescription weight-loss medication that has been FDA-approved since 1976. While newer weight-loss drugs like GLP-1 medications tend to dominate the headlines today, Phendimetrazine remains a viable and affordable short-term option for appropriate patients — particularly those who haven't responded to lifestyle changes alone.

This guide answers the most important questions about Phendimetrazine in plain language.

What Is Phendimetrazine?

Phendimetrazine is a sympathomimetic amine — a type of stimulant medication that mimics the effects of naturally occurring chemicals in the body that activate the sympathetic nervous system. It belongs to the anorectic (appetite-suppressing) drug class, chemically related to the amphetamines.

It was formerly sold under the brand name Bontril PDM and Bontril Slow Release, both of which have been discontinued in the U.S. Today, Phendimetrazine is available only as a generic medication, manufactured by companies including Glenmark and Nucare.

What Is Phendimetrazine Used For?

The FDA-approved use of Phendimetrazine is as a short-term adjunct therapy for the management of exogenous obesity — meaning weight gain caused primarily by overeating and lifestyle factors rather than an underlying medical condition.

It is intended to be used alongside a calorie-restricted diet and an exercise program — not as a standalone treatment. It is not approved for long-term use; most prescriptions are for a few weeks at a time.

To qualify for a Phendimetrazine prescription, you generally need:

• A BMI of 30 kg/m² or higher (obese), OR
• A BMI of 27 kg/m² or higher (overweight) with at least one weight-related health condition, such as hypertension, type 2 diabetes, or high cholesterol

How Does Phendimetrazine Work?

Phendimetrazine is a prodrug — meaning it is converted by the body into its active form after you take it. Approximately 30% of an oral dose is converted into phenmetrazine, which is the pharmacologically active compound responsible for Phendimetrazine's appetite-suppressing effects.

Phenmetrazine acts as a norepinephrine-dopamine releasing agent (NDRA). It stimulates the release of these neurotransmitters in the brain, which suppresses appetite, increases heart rate and blood pressure, and boosts energy metabolism. The combined effect is that you feel less hungry and more energetic, helping you eat less and stay active.

Dosage: How Do You Take Phendimetrazine?

Phendimetrazine comes in two formulations:

• Immediate-release tablets (35 mg): Taken 2 to 3 times per day, 1 hour before meals. The maximum daily dose is 70 mg three times per day (210 mg total per day), but most patients take a lower dose.
• Extended-release capsules (105 mg): Taken once daily, 30-60 minutes before the morning meal. The capsule should be swallowed whole — do not crush, chew, or open it, as this will release the full dose at once.

Always follow your prescriber's instructions. Your dose may be lower than the maximum, and your doctor will adjust based on your response and tolerability.

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Who Should NOT Take Phendimetrazine?

Phendimetrazine is not appropriate for everyone. It should not be taken by people who:

• Have glaucoma (increased eye pressure)
• Have cardiovascular disease (coronary artery disease, arrhythmias, congestive heart failure, uncontrolled hypertension)
• Have hyperthyroidism (overactive thyroid)
• Have a history of substance use disorder or drug abuse
• Are pregnant or breastfeeding
• Have used an MAO inhibitor (MAOI) within the past 14 days
• Are under 17 years old

Is Phendimetrazine the Same as Phentermine?

No — they're different medications, though both are sympathomimetic amine anorexiants used for short-term weight management. Phentermine is a Schedule IV drug (lower abuse potential classification than Phendimetrazine's Schedule III), more widely available, and the most commonly prescribed weight-loss medication in the U.S. Phendimetrazine is a Schedule III controlled substance and technically has a higher abuse potential classification, though both are FDA-approved for appropriate use.

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If you've been prescribed Phendimetrazine and are having trouble locating it at your pharmacy, medfinder can help. Enter your medication, dosage, and location, and medfinder will check pharmacies near you to find which ones can fill your prescription.