Benzphetamine

Benzphetamine is an appetite suppressant that affects the central nervous system and is used together with diet and exercise to treat obesity.

• Benzphetamine is available under various brand names: Didrex, Regimex

Common side effects of Benzphetamine include:

• feeling restless or hyperactive.
• headache, dizziness, tremors.
• sleep problems (insomnia).
• increased sweating.
• dry mouth or an unpleasant taste in your mouth.
• nausea, diarrhea upset stomach; or
• skin rash.

Serious side effects of Benzphetamine include:

• hives. 
• difficulty breathing. 
• swelling of the face, lips, tongue, or throat.
• shortness of breath (even with mild exertion), swelling, rapid weight gain.
• chest pain, feeling like you might pass out.
• pounding heartbeats or fluttering in your chest.
• confusion or irritability, unusual thoughts, or behavior; or
• dangerously high blood pressure (severe headache, blurred vision, buzzing in your ears, anxiety, confusion, chest pain, shortness of breath, uneven heartbeats, seizure).

Rare side effects of Benzphetamine include:

• none

Seek medical care or call 911 at once if you have the following serious side effects:

• Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
• Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
• Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

Adult and pediatric dosage

Tablet: Schedule III

• 25 mg (Regimex)
• 50 mg (Didrex)

Weight management, short-term

Adult dosage

• Oral: Initial: 25 to 50 mg once daily; may increase up to 50 mg 3 times daily based on response and tolerability. 
• Evaluate weight loss after 4 weeks; continue therapy only if satisfactory weight loss (eg, 4 pounds or as clinically appropriate) has occurred.
• Maximum duration: 12 weeks.

Obesity (short-term); adjunctive therapy:

Pediatric dosage

• Adolescents above17 years: 
• Oral: Initial: 25 to 50 mg once daily; may increase to 25 to 50 mg 1 to 3 times daily based on response.

Dosage Considerations – Should be Given as Follows: 

• See “Dosages”

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Benzphetamine has severe interactions with the following drugs:
  • isocarboxazid
  • linezolid
  • methylphenidate
  • phenelzine
  • selegiline transdermal
  • tranylcypromine
• Benzphetamine has serious interactions with at least 33 other drugs.
• Benzphetamine has moderate interactions with at least 192 other drugs.
• Benzphetamine has minor interactions with the following drugs:
  • desmopressin
  • eucalyptus
  • levoketoconazole
  • ribociclib
  • sage

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

Contraindications

• Do not use benzphetamine 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.
• You should not take benzphetamine if you are allergic to it, or if you have:
  • coronary artery disease (hardening of the arteries);
  • heart disease, heart rhythm disorder.
  • severe or uncontrolled high blood pressure.
  • overactive thyroid.
  • glaucoma.
  • if you are pregnant.
  • if you have a history of drug or alcohol abuse; or
  • if you have used any other diet pills within the past year.

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Benzphetamine?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Benzphetamine?”

Cautions

• Benzphetamine can harm an unborn baby or cause birth defects. Do not use benzphetamine if you are pregnant.
• Do not use benzphetamine 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.
• Taking benzphetamine together with other diet medications (including medicines available over the counter) can cause a rare fatal lung disorder called pulmonary hypertension. Do not take benzphetamine with any other diet medications without your doctor's advice.
• Benzphetamine may be habit-forming and should be used only by the person it was prescribed for. Never share benzphetamine with another person, especially someone with a history of drug abuse or addiction. Keep track of the amount of medicine used from each new bottle. Benzphetamine is a drug of abuse and you should be aware if anyone is using your medicine improperly or without a prescription.
• Drinking alcohol can increase certain side effects of benzphetamine.
• To prevent sleep problems, avoid taking this medication late in the afternoon.
• Benzphetamine may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Pregnancy and Lactation

• FDA pregnancy category X. This medication can harm an unborn baby or cause birth defects. Do not use benzphetamine if you are pregnant. Tell your doctor right away if you become pregnant during treatment. Use effective birth control while you are using this medication.
• Lactation
  • Benzphetamine can pass into breast milk and may harm a nursing baby. You should not breastfeed while taking benzphetamine.