Report on Didrex Side Effects and Usage by AskDocWeb

About Didrex

Picture of Didrex

What is Didrex?

Didrex is the brand name of the generic drug Benzphetamine, (benz-FET-a-meen), one of a group of amphetamine-like drugs called “anoretics” or “anorexigenics”. It is an appetite suppressant used along with diet, exercise, and behavior therapy for the short-term management of obesity.

Didrex is also used for the treatment of narcolepsy, attention deficit disorder with hyperactivity, abnormal behavioral syndrome in children (minimal brain dysfunction), and depression.

How does Didrex work?

Didrex reduces appetite by acting on the satiety center in the brain (the part that controls appetite). It also stimulates your central nervous system, increases your heart rate and blood pressure.

What side effects do users of Didrex report?

Anxiety or nervousness

Palpitations (some people thought they were having a heart attack)

Diarrhea or constipation

Dry mouth or an unpleasant taste in the mouth

Headache or dizziness

Impotence or changes to sex drive (altered libido)


Restlessness or tremor

What are the symptoms of overdose?

Symptoms of overdose may include restlessness, tremor, rapid breathing, confusion, hallucinations, nausea, vomiting, diarrhea, and stomach cramps. If you think you overdosed, contact your local poison control center or emergency room immediately.

If you miss a dose of Didrex

If you miss a dose of Didrex, take it as soon as possible. But, DO NOT take 2 doses at once.

Conditions you should tell your Doctor about before taking Didrex:

Anxiety disorder

Arteriosclerosis (hardening of the arteries)

Diabetes (may alter your insulin requirements)

Epilepsy or another seizure disorder


Heart disease or high blood pressure

History of drug or alcohol abuse

Problems with your thyroid

Inform your doctor of any other medical conditions, allergies or pregnancy. Not for use in nursing.

Before any medical or dental treatments, emergency care, or surgery, tell the doctor or dentist that you are using Didrex. Do not take Didrex if you are pregnant. Didrex is excreted in breast milk. Do not breast feed while taking Didrex.

Tell Your Doctor if you’re taking any of the following medicines:

Amitriptyline (Elavil)

Amoxapine (Asendin)

Clomipramine (Anafranil)

Desipramine (Norpramin)

Doxepin (Sinequan)




Imipramine (Tofranil)

Monoamine oxidase inhibitors (MAOIs).

Nortriptyline (Pamelor)

Protriptyline (Vivactil)

Vitamin C supplements decrease the effectiveness of this drug.

Storing Didrex

Didrex must be stored at room temperature below 77 degrees F (25 degrees C) in a tightly closed container, away from heat, light and children.

General Notes

Remember that Didrex as a stimulant and is habit-forming. You can become physically or psychologically dependent on this medication.

You must not exceed the recommended dose or take this medicine for longer than prescribed without checking with your doctor. Exceeding the recommended dose or taking this medicine for longer than prescribed may cause serious side effects. If you take Didrex several weeks in a row and stop suddenly, you may have withdrawal symptoms.

The maximum recommended duration of therapy is 8 to 12 weeks.

Adverse reactions and side effects may be more common in people over 60.

Do not drive or do anything else that could be dangerous until you know how you react to Didrex.

Take Didrex about 30 minutes before a meal. Your last dose of the day must be taken at least 4 to 6 hours before bedtime. If you will be taking Didrex once a day, take it in the morning.

Use moderation when drinking alcohol if you drink at all while using this drug.

Common Misspellings for Didrex

Didrex is often misspelled, as many people hear the word verbally, write it down and spell it incorrectly. Here are a few of the most common misspellings for Didrex: Didrax, Dedrax, Ditrax, Didarex, and Didrix.

Didrex Feedback

If you’ve used Didrex, please help others by adding your feedback. What would you tell someone considering using this product? Please remember that we do not give medical advice. That is for your local health care provider, who is familiar with your medical history. You can use the form below to add your comments, feedback or Didrex review.

Date: 1/4/2004
I have been going up and down on my weight and I am tired of all the diet pills I am over weight and I read this article about your pill. Do you think this can help me not eat as much if I am 215 pounds and 5-5 in height.


AskDocWeb: Whether this pill is right for you is something you need to talk with your doctor about.

extremely addictive
Date: 2/9/2004
Didrex is extremely addictive and is similar in its effect to Methamphetamine. If you have ANY predisposition to addiction, take my advice and STAY AWAY FROM IT. It is ruining my life.


Four months of Didrex
Date: 2/10/2004
I’ve been on Didrex for four months. I did loose weight but once I tried to stop taking it, I found I was addicted to them. Once stopped, I found I was sleeping almost all day. I couldn’t help but sleep. I am seeking counselling and need professional help. I would not recommend taking didrex.


If you have a history of addiction
Date: 3/3/2004

I knew better – as I am a recovering addict – and decided to use Didrex anyway — did really well, took as prescribed until about 3 months when I just went crazy and am now taking approx. 10 a day. I have lost 60 lbs. and have 20 to go.

I KNOW all about phys. and psycho. addiction and have been trying to wean myself off. I am now going to seek out a real live doctor and get help to get off it ….

I been taking it 5 months

Obviously I knew not to ever take it, yet made a decision to do so anyway. My didex experience started innocently enough, yet knowing I was an addict, it is my own fault for ordering any in the first place. But (I) would like to say – it’s gonna be ok – I am resolved now to get a doctor next week who will work with me around getting off these things. I would tell anyone out there, hey, if you DO NOT have a history of addiction, go for it. SHORT TERM AS PRESCRIBED ONLY – and get off it after 8 weeks – if you have a history of addiction — you will surely end up like me – I do not feel I will “use” any other drug now because I am addicted to didrex after a long period (9 years of clean and sober) — I do not feel I am needing to use major drugs again or any drugs again.

What I see and need to say is this — IT WILL KICK YOU back into addiction — and having been sober so long before it — I really am displeased with being “addicted” again to anything — it is so freeing to be free of the “need” for some pill, drink, smoke, whatever. So it has shown me, I actually PREFER being sober now.

So that’s my story — Obviously, anyone with any past addictions should not use this or any diet pill like it —

Regardless of if I stay fat or whatever — but sure am glad I lost 60 lbs.! MY DIET WAS WHAT DID THE WEIGHT LOSS — DIDREX was for keeping me from cheating so I could stay on it.

I can see if I had stopped it in the 8-12 weeks it should have been stopped — it might not have been a problem — since I had 78 lbs. to lose — I kept ordering it – and now deal with this problem. Good luck to all. I will definately be happy to get off it.


Recommend Didrex?
Date: 4/1/2004
Hi. I’m slightly over-weight. I’ve just read about “Didrex”.. I’m also on anti-depressants “EFEXOR XR 75mg”. Would you recommend Didrex and can I get in from my doc in the UK?

Awaiting your reply

AskDocWeb: Didrex is for short-term management of obesity. If you are only slightly overweight then Didrex is not for you.

On/Off Didrex
Date: 4/9/2004
On/Off then on again. Didrex prescribed for treatment of Narcolepsey after Provigil less than effective. Also being treated for ADHD with Dexedrine. Was taken off both medications when I started having problem with sleeping deeply 16 hours at a stretch compared to my usual 8 hours a night. My symptoms associated with ADHD and narcolepsey returned. I did not feel addicted nor did it cause me to sleep any less. For me it was the antidepressent Paxil that turned on me after a year being treated for depression. I stopped (very slowly) the Paxil, sleep habits became normal, restarted Didrex then Dexedrine which successfully aleviated symptoms of ADHD and Narcolepsey. Doctors thinking the abnormal sleep was depression oriented, restarted me on Paxil and within 4 days I was sleeping 16 hours again.

So now I’ve stopped Paxil again. Advice: medications can turn on you, what was good before can be a bummer later. Keep your doctor adviced religiously of any and all side effects even if they might seem minor to you. It can save you from the kind of situation that caused me a lot of emotional problems.


Date: 5/5/2004
Well, it’s 3:00 AM and I have to be up in about 3 hrs to go to work at my “professional” job. So what am I doing? Wondering how in the hell this happened, that’s what. I’ve been on Didrex for almost three years now. I take 100-150 mg/day, usually. I’m moderately overweight (bmi about 31 or so). I may have lost a few pounds on this stuff initially, but weigh more now than ever. Didrex makes me feel like I’m competent, basically (hey, I’m easy). I don’t feel like I need to take more (am afraid to actually, because my BP is running rather high on this stuff). But I really can’t stop. When I try to, I feel horrible. No motivation at all. Dull, lethargic and depressed. Not surprisingly, I wound up testing positive for amphetamines on a drug test at work and nearly lost my job over it because I got the pills off the internet and no doctor would vouch for the Rx. Had to hire a lawyer and everything. Well, even after all that, I’m still taking it. And now it’s almost 3:20 AM. Any thoughts?

No Name

AskDocWeb: Sounds like you could benefit from some professional medical help. If you want to stop and can’t do that by yourself, then get someone to help.

Long term effects
Date: 6/7/2004
This sounds like a pretty negative drug when simply reviewing these comments, except that it seems to work much better than caffeine as a stimulant. Since it’s so addictive, I’m wondering what the possible long-term effects might be. Is it dangerous to take it for years, and if so, what are the specific risks?

No Name

AskDocWeb: To our knowledge, the long-term effects of using Didrex have not been studied. The manufacturer specifically states that this drug is only for the short-term management of obesity.

Withdrawal from Didrex
Date: 6/8/2004
Hi, Wanted to update you all on my progress — After running through 180 pills in 6 days to the tune of 1,500 mg. a day — which scare the daylights out of me (that’s 30 pills a day!) YES, have VERY high tolerance comes from being an ADDDICT! Anyway, I am now entering my 3rd week OFF Didrex completely ….

VERY BAD physical withdrawal and CANNOT FIND ANY INFORMATION ON PHYSICAL WIDTHDRAWL from Didrex. I have had NO mental withdrawal at this point, I did have that happen after the 180 pills but it lasted only a few days. I am severely physically addicted and I am seeing a doctor now regularly for my progress and am on 4 different meds to help with the withdrawal. Cogentin, Prozac, Seriquel, and Clonidine… It’s a BIGTIME withdrawal from Didrex, not unlike the one I went through with Valium. I did not take Didrex seriously enough, and now am paying for that. IT IS AWEFUL!

Don’t know how long this will last — but am sooooo glad to be 2 1/2 – 3 weeks OFF DIDREX – I used it for 7 months – 3 of which was normal 150 mg. daily – I can see from my Most recent post:in March it took 2 months to get a reality check – I was not even aware of how much I used – but in the end – it was WAY TOO MUCH – 1,200 mg. daily for approximately 1 month then going through 180 pills in 6 days. WOW – scared me very much and I took the bottle to my friends house – and picked up doses – weaning myself due to not wanting to lose all the things I’ve worked so hard for as everyone told me I’d have to go inpatient detox – NOT! Cannot do that again… so I took MYSELF off it…

I took myself off it down from 1,200 to 900 to 650 and on and on for 3 weeks till I finally had an appt. for a Dr. who now is monitoring me around my withdrawal – yet THEY had no info. on the physical withdrawal – please advise me of any information you can point me to or give me regarding the physical withdrawal – at going on 3 weeks – it is still very intense at times despite the meds. I am finally off it and glad – saved myself by the skin of my teeth! Please do not take this med if you are in recovery! Thanks –


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Most recent post: >February 28, 2017

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