Benzphetamine

Why is this medicine prescribed?

Benzphetamine is used as a short-term treatment with diet to help certain people who are obese to lose weight. Benzphetamine is in a class of medications called central nervous system stimulants.It works by changing the amounts of certain natural substances in the brain.

Are there other uses for this medicine?

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

How should this medicine be used?

Benzphetamine comes as a tablet to take by mouth. It is taken 1 to 3 times a day for no more than a few weeks. Take benzphetamine at around the same time(s) every day.

Take benzphetamine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Your doctor may start you on a low dose of benzphetamine and gradually increase your dose.

Benzphetamine may be habit-forming. Do not take a larger dose, take it more often, or take it for a longer period of time than prescribed by your doctor.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

What special precautions should I follow?

Before taking benzphetamine,

• tell your doctor or pharmacist if you are allergic to this medication, any part of this medication, or any other medications, foods or substances. Tell your doctor or pharmacist about the allergy and what symptoms you had.

• some medications should not be taken with benzphetamine. Other medications may cause dosing changes or extra monitoring when taken with benzphetamine. Make sure you have discussed any prescription and nonprescription medications or herbal products you are currently taking or plan to take before starting benzphetamine with your doctor and pharmacist. Before starting, stopping, or changing any medications while taking benzphetamine, please get the advice of your doctor or pharmacist.

• tell your doctor or pharmacist if you are taking the following medications or have stopped taking them within the past two weeks: monoamine oxidase (MAO) inhibitor such as isocarboxazid (Marplan^®), linezolid (Zyvox^®), phenelzine (Nardil^®), selegiline (Emsam^®, Zelapar^®), and tranylcypromine (Parnate^®).

• tell your doctor if you have or ever have had an irregular heartbeat, heart valve disease, or other heart problems; high blood pressure; glaucoma (increased pressure in the eye that may cause vision loss); hyperthyroidism (condition in which there is too much thyroid hormone in the body); or feelings of anxiety, tension, or agitation. Also, tell your doctor if you drink or have ever drunk large amounts of alcohol or if you use or have ever used street drugs, or overused prescription medications. Your doctor may tell you not to take benzphetamine.

• tell your doctor if you have or have ever had diabetes, pulmonary hypertension (high blood pressure in blood vessels that carry blood to the lungs), or depression or another mental illness.

  .

• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. You should not become pregnant while you are taking benzphetamine. If you become pregnant while taking benzphetamine, call your doctor immediately. Benzphetamine may harm the fetus.

• tell your doctor if you are breastfeeding or plan to breastfeed. You should not breastfeed while you are taking benzphetamine.

• you should know that benzphetamine may make it difficult for you to perform activities that require alertness or physical coordination. Do not drive a car or operate machinery until you know how this medication affects you.

What special dietary instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What should I do if I forget to take a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What side effects can this medicine cause?

Benzphetamine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• nausea
• diarrhea
• dry mouth
• unpleasant taste
• changes in sex drive or ability
• restlessness
• abnormally excited mood
• falling asleep or staying asleep
• dizziness
• sweating
• headache
• uncontrollable shaking of part of the body

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately or get emergency medical treatment:

• shortness of breath; chest pain; fainting; or swelling of the legs, ankles, or feet
• fast, pounding, or irregular heartbeat
• rash, hives, or itching
• believing things that are not true, feeling unusually suspicious of others, or hallucinating (seeing things or hearing voices that do not exist)

Benzphetamine may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (https://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from light, excess heat and moisture (not in the bathroom).

Keep all medication out of sight and reach of children as many containers are not child-resistant. Always lock safety caps. Place the medication in a safe location – one that is up and away and out of their sight and reach. https://www.upandaway.org

Dispose of unneeded medications in a way so that pets, children, and other people cannot take them. Do not flush this medication down the toilet. Use a medicine take-back program. Talk to your pharmacist about take-back programs in your community. Visit the FDA's Safe Disposal of Medicines website https://goo.gl/c4Rm4p for more information.

What should I do in case of overdose?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include:

• restlessness
• uncontrollable shaking of part of the body
• fast breathing
• confusion
• feelings of panic
• aggressive behavior
• depression
• fast or irregular heartbeat
• nausea, vomiting, diarrhea, or stomach cramps
• fever
• muscle weakness or aching
• dark red or cola-colored urine
• tiredness or weakness

What other information should I know?

Keep all appointments with your doctor.

Before having any laboratory test, tell your doctor and the laboratory personnel that you are taking benzphetamine.

Do not let anyone else take your medication. Benzphetamine is a controlled substance. Prescriptions may be refilled only a limited number of times; ask your pharmacist if you have any questions.

Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.

Brand name(s)

• Didrex^®¶

^¶ This branded product is no longer on the market. Generic alternatives may be available.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS^® Patient Medication Information™. © Copyright, 2026. The American Society of Health-System Pharmacists^®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: January 15, 2026.