Generic Name: phendimetrazine (fen di MEH tra zeen)
Brand Names: Adipost, Bontril, Melfiat
What is Bontril?
Bontril (phendimetrazine) is a sympathomimetic amine, which is similar to an amphetamine. It is also known as an "anorectic" or "anorexigenic" drug. Bontril stimulates the central nervous system (nerves and brain), which increases your heart rate and blood pressure and decreases your appetite.
Bontril is used as a short-term supplement to diet and exercise in the treatment of obesity.
Bontril may also be used for purposes not listed in this medication guide.
Bontril may cause blurred vision or impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly. Bontril may be habit-forming and should be used only by the person it was prescribed for. Keep the medication in a secure place where others cannot get to it.
Weight loss during pregnancy can harm an unborn baby, even if you are overweight. Do not use Bontril if you are pregnant.
Do not stop using Bontril suddenly after long-term use, or you could have unpleasant withdrawal symptoms. Ask your doctor how to avoid withdrawal symptoms when you stop using Bontril. Do not crush, chew, break, or open the extended-release Bontril capsule. Swallow it whole. Breaking or opening the pill may cause too much of the drug to be released at one time.
Before taking this medicine
Do not use Bontril if you have used an MAO inhibitor such as furazolidone (Furoxone), isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam, Zelapar), or tranylcypromine (Parnate) in the last 14 days. A dangerous drug interaction could occur, leading to serious side effects. You should not use Bontril if you are allergic to phendimetrazine, or if you have:
a history of heart disease (coronary artery disease, heart rhythm problems, congestive heart failure, pulmonary hypertension);
heart murmur or heart valve disorder;
severe or uncontrolled high blood pressure;
severe agitation or nervousness;
if you have a history of drug or alcohol abuse; or
if you are allergic to other diet pills, amphetamines, stimulants, or cold medications.
To make sure you can safely take Bontril, tell your doctor if you have any of these other conditions:
high blood pressure;
an anxiety disorder;
epilepsy or seizure disorder; or
if you have used other diet pills in the past year (prescription, over-the-counter, or herbal products).
Bontril may be habit forming and should be only be used by the person for whom it was prescribed. Never share Bontril with another person, especially someone with a history of drug abuse or addiction. Keep the medication in a place where others cannot get to it.
FDA pregnancy category X. Weight loss during pregnancy can harm an unborn baby, even if you are overweight. Do not use Bontril if you are pregnant. Tell your doctor right away if you become pregnant during treatment. It is not known whether phendimetrazine passes into breast milk or if it could harm a nursing baby. You should not breast-feed while you are using phendimetrazine. Bontril should not be given to a child younger than 17 years old.
See also: Pregnancy and breastfeeding warnings (in more detail)
How should I take Bontril?
Take Bontril exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label. This medicine should be taken only for a short time, such as a few weeks.
Bontril is usually taken once daily. Follow your doctor's instructions.
Take Bontril on an empty stomach, 30 to 60 minutes before your morning meal. Do not crush, chew, break, or open the extended-release capsule. Swallow it whole. Breaking or opening the pill may cause too much of the drug to be released at one time. You should lose at least 4 pounds during the first 4 weeks of taking Bontril and eating a low calorie diet. Tell your doctor if you do not lose at least 4 pounds after taking the medication for 4 weeks.
Do not stop using Bontril suddenly after long-term use, or you could have unpleasant withdrawal symptoms. Ask your doctor how to avoid withdrawal symptoms when you stop using this medicine.
Never take more of this medication than is prescribed for you. Too much Bontril could be very dangerous to your health. Talk with your doctor if you have increased hunger or if you otherwise think the medication is not working properly. Taking more of this medication will not make it more effective and can cause serious, life-threatening side effects.
Store Bontril at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
A dose taken too late in the day will cause insomnia.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of Bontril can be fatal.
Symptoms of a Bontril overdose include nausea, vomiting, diarrhea, stomach cramps, confusion, panic, hallucinations, extreme restlessness, feeling tired or depressed, ringing in your ears, chest pain, slow heart rate, weak pulse, fainting, seizure, or slow breathing (breathing may stop).
What should I avoid?
Bontril may cause blurred vision or impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly.
Drinking alcohol can increase certain side effects of Bontril.
Bontril side effects
Get emergency medical help if you have any of these signs of an allergic reaction to Bontril: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Stop using Bontril and call your doctor at once if you have a serious side effect such as:
feeling short of breath, even with mild exertion;
chest pain, feeling like you might pass out;
swelling in your ankles or feet;
pounding heartbeats or fluttering in your chest;
confusion or irritability, unusual thoughts or behavior;
feelings of extreme happiness or sadness; or
dangerously high blood pressure (severe headache, blurred vision, buzzing in your ears, anxiety, confusion, chest pain, shortness of breath, uneven heartbeats, seizure).
Less serious Bontril side effects may include:
feeling restless or hyperactive;
headache, dizziness, tremors;
sleep problems (insomnia);
flushing (warmth, redness, or tingly feeling);
diarrhea or constipation, upset stomach; or
increased or decreased interest in sex, impotence.
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.
See also: Side effects (in more detail)
Bontril dosing information
Usual Adult Dose of Bontril for Obesity:
One Slow Release Capsule (105 mg) in the morning, taken 30 to 60 minutes before the morning meal.
Immediate release: 35 mg oral tablet 2 to 3 times daily, 1 hour before meals.
What other drugs will affect Bontril?
Tell your doctor about all other medicines you use, especially:
insulin or oral diabetes medications;
certain blood pressure medications, such as doxazosin (Cardura), prazosin (Minipress), or terazosin (Hytrin); or
any other diet pills.
This list is not complete and other drugs may interact with Bontril. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.
More about Bontril Slow Release (phendimetrazine)
- Bontril SR Sustained-Release Capsules
- Bontril (Advanced Reading)
- Bontril Slow-Release (Advanced Reading)
Related treatment guides
Where can I get more information?
- Your pharmacist can provide more information about Bontril.
- Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Bontril only for the indication prescribed.
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