Generic Name: benzphetamine (Oral route)
Medically reviewed on June 7, 2018
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Appetite Suppressant, Centrally Acting
Chemical Class: Amphetamine (class)
Uses For Didrex
Benzphetamine is used together with a diet plan to help you lose weight. This medicine works by suppressing your appetite .
This medicine is available only with your doctor's prescription .
Before Using Didrex
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of benzphetamine in children below 12 years of age. Safety and efficacy have not been established .
Appropriate studies performed to date have not demonstrated geriatrics-specific problems that would limit the usefulness of benzphetamine in the elderly. However, elderly patients are more likely to have age-related liver, kidney, or heart problems, which may require an adjustment in the dose for patients receiving benzphetamine .
|All Trimesters||X||Studies in animals or pregnant women have demonstrated positive evidence of fetal abnormalities. This drug should not be used in women who are or may become pregnant because the risk clearly outweighs any possible benefit.|
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with Medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
- Methylene Blue
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Morphine Sulfate Liposome
- Opium Alkaloids
- Sodium Bicarbonate
- St John's Wort
Interactions with Food/Tobacco/Alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other Medical Problems
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:
- Agitation or anxiety, severe or
- Drug abuse or dependence, history of or
- Glaucoma or
- Heart or blood vessel disease or
- High blood pressure, moderate or severe or
- Overactive thyroid—This medicine should not be used if any of these conditions exist. Serious unwanted effects could occur .
- Diabetes mellitus or
- High blood pressure, mild or
- Mental illness—Use with caution. This medicine may make these conditions worse .
Proper Use of Didrex
It is best to take this medicine in the mid-morning or mid-afternoon. Taking this medicine late in the afternoon or evening could make it harder for you to fall asleep .
Carefully follow your doctor's instructions about a special diet plan that will help you lose weight .
The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (tablets):
- For weight loss:
- Adults and teenagers—At first, 25 to 50 milligrams (mg) once a day. Your doctor may increase your dose if needed. However, the dose is usually not more than 25 to 50 mg three times a day.
- Children below 12 years of age—Use and dose must be determined by your doctor .
- For weight loss:
If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions While Using Didrex
It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly .
This medicine may be habit-forming. If you feel that the medicine is not working as well, do not use more than your prescribed dose. Call your doctor for instructions .
If you will be taking this medicine for a long time, do not stop taking it without first checking with your doctor. Your doctor may want you to gradually reduce the amount you are taking before stopping completely .
Check with your doctor right away if you think that you may be pregnant. Benzphetamine may cause birth defects or other problems in the baby if taken during pregnancy. Use an effective form of birth control to keep from getting pregnant .
You should not use this medicine if you have used an MAO inhibitor (MAOI) such as Eldepryl®, Marplan®, Nardil®, or Parnate® within the past 14 days .
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines, and herbal or vitamin supplements .
This medicine may cause some people to feel a false sense of well-being or to become dizzy, lightheaded, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or not alert.
Didrex Side Effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
- convulsions (seizures)
- fast, irregular, pounding, or racing heartbeat or pulse
- feeling lightheaded or faint
- hives or welts
- mood or other mental changes
- numbness or tingling in the arms or legs
- redness of skin
- shakiness in the legs, arms, hands, or feet
- skin rash
- trembling of the hands or feet
- trouble with sleeping
- trouble with thinking, speaking, or walking
- unable to sleep
- unusual feeling of excitement
- Chest discomfort or pain
- difficulty breathing
- feeling sad or empty
- lack of appetite
- loss of interest or pleasure
- severe mental changes
- shortness of breath
- swelling of the feet or lower legs
- trouble with concentrating
- trouble with breathing
- unusual tiredness or weakness
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
- Blurred vision
- change in consciousness
- dark-colored urine
- dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly
- loss of consciousness
- muscle cramps or spasms
- muscle pain or stiffness
- physical attempt to injure oneself
- pounding in the ears
- rapid, shallow breathing
- severe anxiety or feeling of panic
- stomach cramps
- violent actions
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- Decrease in sexual ability, desire, drive, or performance
- decreased interest in sexual intercourse
- dry mouth
- inability to have or keep an erection
- increase in sexual ability, desire, drive, or performance
- increased interest in sexual intercourse
- unpleasant taste
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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