Skip to Content

Didrex

Generic Name: Benzphetamine (benz FET a meen)
Brand Name: Didrex, Regimex

Medically reviewed on September 5, 2018

Uses of Didrex:

What do I need to tell my doctor BEFORE I take Didrex?

For all patients taking Didrex (benzphetamine):

  • If you have an allergy to benzphetamine or any other part of Didrex (benzphetamine).
  • If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
  • If you have any of these health problems: Blood vessel disease, glaucoma, high blood pressure, nervous, anxious, or tense state, overactive thyroid disease, or structure problems of the heart or other heart problems.
  • If you have ever abused drugs.
  • If you are pregnant or may be pregnant. Do not take Didrex (benzphetamine) if you are pregnant.
  • If you are breast-feeding. Do not breast-feed while you take Didrex (benzphetamine).
  • If you have taken certain drugs used for low mood (depression) like isocarboxazid, phenelzine, or tranylcypromine or drugs used for Parkinson's disease like selegiline or rasagiline in the last 14 days. Taking Didrex (benzphetamine) within 14 days of those drugs can cause very bad high blood pressure.
  • If you are taking another drug for weight loss or have taken one within the last year.

Children:

  • If your child is younger than 12 years of age. Do not give Didrex (benzphetamine) to a child younger than 12 years of age.

This is not a list of all drugs or health problems that interact with Didrex (benzphetamine).

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take Didrex (benzphetamine) with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take Didrex?

  • Tell all of your health care providers that you take Didrex (benzphetamine). This includes your doctors, nurses, pharmacists, and dentists.
  • Avoid driving and doing other tasks or actions that call for you to be alert until you see how Didrex (benzphetamine) affects you.
  • If you have been taking Didrex (benzphetamine) for a long time or at high doses, it may not work as well and you may need higher doses to get the same effect. This is known as tolerance. Call your doctor if Didrex (benzphetamine) stops working well. Do not take more than ordered.
  • If you have been taking Didrex (benzphetamine) for many weeks, talk with your doctor before stopping. You may want to slowly stop Didrex (benzphetamine).
  • People who take drugs for weight loss like Didrex (benzphetamine) may have a higher chance of having raised pressure in the lungs. This is rare but is often deadly. Talk with your doctor.
  • If you have high blood sugar (diabetes), you will need to watch your blood sugar closely.
  • Do not take more than what your doctor told you to take. Taking more than you are told may raise your chance of very bad side effects.
  • Follow the diet and workout plan that your doctor told you about.
  • This medicine may cause harm to the unborn baby if you take it while you are pregnant. If you are pregnant or you get pregnant while taking Didrex (benzphetamine), call your doctor right away.

How is this medicine (Didrex) best taken?

Use Didrex (benzphetamine) as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • Take Didrex (benzphetamine) early in the day to prevent sleep problems.
  • Take with or without food.

What do I do if I miss a dose?

  • Take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.

See also: Dosage Information (in more detail)

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of high blood pressure like very bad headache or dizziness, passing out, or change in eyesight.
  • Chest pain or pressure or a fast heartbeat.
  • A heartbeat that does not feel normal.
  • Very nervous and excitable.
  • Lowered interest in sex.
  • Shortness of breath.
  • Swelling in the arms or legs.

What are some other side effects of Didrex?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Dizziness.
  • Feeling nervous and excitable.
  • Not able to sleep.
  • Headache.
  • Restlessness.
  • Shakiness.
  • Sweating a lot.
  • Dry mouth.
  • Loose stools (diarrhea).
  • Upset stomach.
  • Bad taste in your mouth.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at http://www.fda.gov/medwatch.

See also: Side effects (in more detail)

If OVERDOSE is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out Didrex?

  • Store at room temperature.
  • Protect from light.
  • Store in a dry place. Do not store in a bathroom.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

Consumer information use

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else's drugs.
  • Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
  • Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
  • Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about Didrex (benzphetamine), please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

More about Didrex (benzphetamine)

Consumer resources

Other brands: Regimex

Professional resources

Related treatment guides

Hide