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Regimex

Generic Name: benzphetamine (benz FET ah meen)
Brand Name: Didrex, Regimex

Medically reviewed on November 20, 2017.

What is Regimex?

Regimex is a stimulant that is similar to an amphetamine. This medicine is an appetite suppressant that affects the central nervous system.

Regimex is used together with diet and exercise to treat obesity (overweight).

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

Important Information

Regimex can harm an unborn baby or cause birth defects. Do not use this medicine if you are pregnant.

Do not use Regimex 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 Regimex together with other diet medications (including medicines available over the counter) can cause a rare fatal lung disorder called pulmonary hypertension. Do not take this medicine with any other diet medications without your doctor's advice.

Regimex may be habit-forming and should be used only by the person it was prescribed for. Never share this medicine 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. This medicine is a drug of abuse and you should be aware if anyone is using your medicine improperly or without a prescription.

Before taking this medicine

Do not use Regimex 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 Regimex together with other diet medications (including medicines available over the counter) can cause a rare fatal lung disorder called pulmonary hypertension. Do not take this medicine with any other diet medications without your doctor's advice.

You should not take Regimex if you are allergic to it, or if you have:

To make sure Regimex is safe for you, tell your doctor if you have:

  • high blood pressure;

  • diabetes; or

  • a thyroid disorder.

Regimex may be habit-forming and should be used only by the person it was prescribed for. Never share this medicine 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. This medication can harm an unborn baby or cause birth defects. Do not use Regimex 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.

Benzphetamine can pass into breast milk and may harm a nursing baby. You should not breast-feed while taking benzphetamine.

Do not give this medication to a child younger than 12 years old.

How should I take Regimex?

Take 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.

Regimex is usually taken once each day, mid-morning or mid-afternoon.

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.

Regimex should be taken only for a short time, such as a few weeks. Tell your doctor if you have not lost any weight after 4 weeks of treatment.

Regimex is only part of a complete program of treatment that may also include diet, exercise, and weight control. Follow your diet, medication, and exercise routines very closely.

Store at room temperature away from moisture and heat.

Keep track of the amount of medicine used from each new bottle. Regimex is a drug of abuse and you should be aware if anyone is using your medicine improperly or without a prescription.

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.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of Regimex can be fatal.

Overdose symptoms may include confusion, panic, feeling hostile or aggressive, nausea, vomiting, diarrhea, stomach cramps, fever, muscle pain or weakness, dark colored urine, irregular heartbeat, weak pulse, slow breathing, feeling light-headed, seizure, or fainting.

What should I avoid while taking Regimex?

Drinking alcohol can increase certain side effects of Regimex.

To prevent sleep problems, avoid taking this medication late in the afternoon.

Regimex may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Regimex side effects

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

Stop using Regimex and call your doctor at once if you have:

  • 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).

Common side effects may 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.

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)

What other drugs will affect Regimex?

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with Regimex, especially:

This list is not complete. Other drugs may interact with benzphetamine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

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

More about Regimex (benzphetamine)

Consumer resources

Other brands: Didrex

Professional resources

Related treatment guides

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