Phendimetrazine is similar to an amphetamine. Phendimetrazine stimulates the central nervous system (nerves and brain), which increases your heart rate and blood pressure and decreases your appetite.

Phendimetrazine is used together with diet and exercise to treat obesity.

Phendimetrazine may also be used for purposes not listed in this medication guide.

You should not use phendimetrazine if you are allergic to it, or if you have:

• severe heart problems;
• advanced coronary artery disease (clogged arteries);
• severe or uncontrolled high blood pressure;
• overactive thyroid;
• glaucoma;
• extreme agitation or nervousness; or
• a history of drug abuse.

Do not use phendimetrazine if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

Weight loss during pregnancy can harm an unborn baby, even if you are overweight. Do not use phendimetrazine if you are pregnant. Tell your doctor right away if you become pregnant during treatment.

Tell your doctor if you have ever had:

• heart disease or coronary artery disease;
• high blood pressure;
• diabetes (your diabetes medication dose may need to be adjusted); or
• an allergy to food dye or aspirin.

Phendimetrazine is not approved for use by anyone younger than 12 years old.

It may not be safe to breast-feed while using this medicine. Ask your doctor about any risk.

Use Phendiet (Oral) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

• pounding heartbeats or fluttering in your chest;
• tremors, severe agitation, feeling restless, trouble sleeping;
• unusual changes in mood or behavior;
• little or no urination; or
• increased blood pressure--severe headache, blurred vision, pounding in your neck or ears, anxiety, nosebleed.

Common side effects may include:

• flushing (warmth, redness, or tingly feeling);
• increased sweating or urination;
• dizziness, headache;
• blurred vision;
• dry mouth, nausea;
• diarrhea, constipation, stomach pain; or
• increased or decreased interest in sex.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Drinking alcohol with this medicine can cause side effects.