Benzphetamine vs. Phentermine (4 Key Differences)

January 9, 2024 |

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In this article, you will discover how Benzphetamine and Phentermine differ regarding their safety, effectiveness, and user popularity.

Apparently, both of these weight loss pills have a similar mechanism of action and belong to the same class of drugs. But they are not entirely the same.

Compared to Benzphetamine, Phentermine has a more potent weight loss benefit at lower doses. Moreover, Benzphetamine has greater addiction potential and cannot be prescribed with other drugs. Whereas you can take Phentermine in certain drug combinations.

Since there’s more to it, I’ve assessed the difference between the two drugs based on their dosage regimes, contraindications, side effects, and user reviews in the following sections.

So, keep reading to know the details.

Benzphetamine Vs. Phentermine – Key Differences

Benzphetamine and Phentermine are FDA-approved weight loss prescription drugs classified as sympathomimetic amines.

This class of drugs modulates the release of certain neurotransmitters like nor-epinephrine to stimulate the sympathetic nervous system and suppress appetite. Therefore, both these drugs will help you shed a few pounds when taken in combination with an exercise regime and calorie-restricted diet.

However, the two drugs vary in their addiction potential as Phentermine is classified as a DEA Schedule IV drug and has a lower risk of causing dependence. In contrast, Benzphetamine is a DEA Schedule III drug.

Moreover, Phentermine is more potent even at a single dose, while Benzphetamine has to be taken 3-4 times every day at similar doses.

Additionally, Phentermine has better compatibility with underlying health conditions like controlled cardiovascular disease or diabetes than Benzphetamine. But there is still more to know, so here is a detailed comparison of the two drugs.

Benzphetamine vs. Phentermine – Which One Is More Efficacious?

Benzphetamine Effectiveness

Doctors recommend Benzphetamine for obese patients with a BMI of 30 kg/m2 or more.

According to, Benzphetamine is available in a 25 or 50-mg dose and is prescribed one to three times a day according to the patient’s needs.

Clinical trials that evaluated this drug’s efficacy suggest that it may induce an average weight loss of one (0.98) pound per week. Compared to this, the users on have reported an average weight loss of 1 to 4 pounds per week.

What is more, is that one user even reported a rapid weight reduction of as high as 7 pounds in a single week.

But caution is to be taken to prescribe Benzphetamine as monotherapy only.

Phentermine Effectiveness

Phentermine is a suitable obesity treatment for those with a BMI of 30 kg/m2 or greater or a BMI of 27 kg/m2 with comorbidities like diabetes, high cholesterol levels, and high blood pressure.

The average weight loss per week estimated by based on various research and user reviews is 1-4 pounds per week.

Here, the clinical trials have reported a weight loss trend that falls more in the lower range, whereas users self-report a greater weight loss progress.

According to, Phentermine is available in 8, 15, 18.75, 30, and 37.5 mg capsules, tables, or compounding powder and is prescribed either once a day in higher doses or 2-3 times per day in lower doses before or after meals depending on the patient’s condition.

The best part is that it is effective as a monotherapy and can also be prescribed as a combination therapy with drugs such as topiramate to increase its benefit.

Summary: Phentermine is more efficacious as it can be combined with certain drugs and is better than Benzphetamine at inducing weight loss in lower doses.

Benzphetamine vs. Phentermine – Which Has The Least Side Effects?

Benzphetamine Safety And Side Effects

Benzphetamine may cause hypersensitivity reactions and adverse side effects on the cardiovascular system, central nervous system, gastrointestinal system, and endocrine system.

Hence it may commonly cause sleeplessness, hyperactiveness, headache, dry mouth, nausea, bad taste in mouth, diarrhea, sweating, rash, itchiness, or changes in sex drive.

However, in severe cases, you may notice symptoms like psychotic episodes, anxiety, seizures, fast or irregular heartbeat, breathlessness, chest pain or tightness, fainting, swelling of the face, tongue, throat, or lips, hives, or extremely high blood pressure.

Moreover, Benzphetamine is classified in pregnancy category X by FDA, which means that pregnant women should not take it because it may harm the fetus.

Similarly, it should be avoided by breastfeeding mothers as it may pass into the breast milk.

Additionally, lists 33 serious drug contraindications for Benzphetamine and mentions 192 other drugs that may cause moderate drug reactions.

Therefore, inform your doctor of your past prescriptions, especially of antibiotics, anti-diabetic agents, antidepressants, ADHD medicines, CNS stimulants, vitamins, herbal products, over-the-counter diet pills, or if you have taken MAO inhibitors in the last 14 days. Additionally, avoid drinking alcohol with this medicine.

On top of this, Benzphetamine is not recommended for children under 12 years of age and should be used with caution by individuals above 65 years. And it can’t be prescribed to individuals who have glaucoma, thyroid disorders, coronary artery disease, heart problems, or a history of drug abuse.

Phentermine Safety And Side Effects

Phentermine may cause cardiovascular risks, allergic reactions, and side effects on the endocrine system, central nervous system, or gastrointestinal system.

The common side effects it may cause are insomnia, restlessness, itching, headache, dizziness, dry mouth, unpleasant taste in the mouth, diarrhea, constipation, abdominal pain, or changes in libido.

In severe cases, it may cause increased blood pressure, fast heart rate, chest pain, restlessness, lightheadedness, difficulty breathing, loss of consciousness, swelling of the feet or lower legs, extreme fatigue, or tremors.

In addition to this, Phentermine also belongs to pregnancy category X of the FDA because it may cause birth defects and miscarriages.

Correspondingly nursing mothers should also avoid it as it may release into the breast milk.

Regarding drug interactions, has compiled 40 drugs that cause serious reactions with Phentermine and 163 drugs that cause moderate reactions.

Therefore, avoid taking it if you have had MAO inhibitors in the last 14 days, with over-the-counter diet medicines, herbal preparations, certain antibiotics, alcohol, or CNS drugs.

It should be prescribed to individuals of ages above 17 years only, and its geriatric use requires caution and dose adjustments.

Besides that, it can’t be recommended for individuals who have glaucoma, seizure disorders, hyperthyroidism, cardiovascular disease, are in an agitated state, or have who have overdosed on drugs before.

Summary: Phentermine has lesser drug interactions, so it is safer. Otherwise, both drugs have a similar list of side effects and safety profiles.

Benzphetamine vs. Phentermine – Long-term Usage

Benzphetamine Long-term Usage

Benzphetamine can only be taken for a maximum duration of 12 weeks.

Correspondingly, clinical trials in which Benzphetamine was used for longer than 3 months reported an increased risk of developing fatal pulmonary hypertension.

Moreover, it may affect eyesight, cause eye pain or swelling, sudden vision loss, and blurred or tunnel vision. So, it has the potential to cause long-term vision complications if not treated immediately.

Phentermine Long-term Usage

Phentermine is only recommended as a short-term course of fewer than 12 weeks.

But even short-term therapy can cause severe and sometimes fatal consequences if not given early treatment.

These effects include lung and heart problems such as valvular heart disease and pulmonary hypertension and vision problems such as sudden loss or changes in vision, eye pain, swelling, or redness.

Summary: Apart from the side effects, none of the two drugs are FDA approved for prolonged use due to the risk of dependency. However, clinical trials show that a phentermine combination therapy such as ‘Qsymia’ is suitable for long-term use as it has fewer side effects and a better weight reduction potential.

Benzphetamine vs. Phentermine – User’s Review

Benzphetamine User’s Review

On, Benzphetamine has an average rating of 7.5/10 based on 15 user ratings.

And from the 17 reviews, 67% of users reported a positive experience, whereas 20% were unsatisfied with the results.

On WebMD, Benzphetamine has an average user rating of 3.8/5 based on 10 reviews.

Phentermine User’s Review

From the total 2013 ratings on, Phentermine scored an average rating of 8.7/10.

And among the 2322 user reviews, 84% of users were happy with the outcome, while 5% of users reported a negative experience.

Similarly, on WebMD, Phentermine has an overall rating of 4.3/5, derived from 2312 user ratings.

Summary: These stats show that Phentermine is the preferred weight loss drug among users.

Can you take Phentermine With Benzphetamine? (why you shouldn’t)

It may occur to you that combining slimming pills may cause faster weight loss, but the answer to can you take Phentermine with Benzphetamine? is no.

Moreover, I have already mentioned above as well that Benzphetamine should only be used independently.

Here are some reasons why their concomitant use is a risky deal.


Both Phentermine and Benzphetamine stimulate the sympathetic nervous system, aka fight or flight response, to slow down digestion or suppress appetite.

This system is basically taking you towards a more alert state in which the blood flow towards the muscles increases, the pupils dilate, and the heart rate increases.

Therefore, excessive stimulation due to a double dose of these anorexiants may lead to fidgetiness, anxiety, muscle cramps or numbness, hallucinations, upset stomach, vision and eye problems, high blood pressure, etc.

Pulmonary Hypertension

Both these drugs already pose an individual risk of causing pulmonary hypertension.

Combining their intake may further amplify this risk and may cause fatal consequences.

Safer Alternatives To Benzphetamine & Phentermine

Benzphetamine and Phentermine are not suitable for everyone, as they pose many health risks and can’t be taken for longer durations.

Hence, PhenQ and Phen24 may be better alternatives to them since these over-the-counter weight loss pills have minimum to no side effects and can be taken for as long as you want.

So, here is a brief review of their benefits, cost, pros, and cons.

1. PhenQ Appetite Suppressant

PhenQ bottle tablet

PhenQ is an all-natural weight-loss pill that triggers five weight-loss-inducing mechanisms. This pill suppresses appetite, burns fat, prevents fat accumulation, boosts energy, and improves mood and focus.

It contains the patented proprietary blends of a-Lacys Reset and capsimax powder, including ingredients such as caffeine, nopal cactus, and L-carnitine fumarate.

First is the a-Lacys Reset, which is proven by scientific studies to increase satiety, give energy, and induce fat-burning mechanisms and lipolysis.

Second is its capsimax powder which encapsulates the capsinoids found in red and hot peppers in beads. It burns fat and prevents its accumulation while reducing the risk of causing stomach irritation.

Next, there’s caffeine which enhances alertness, provides energy, and triggers thermogenesis to speed up your slimming process.

The addition of nopal cactus in the formulation is supported by studies that show that it can alter the gut microbiome to treat obesity. It is also a source of dietary fiber and promotes a feeling of fullness.

Last but not least, L-carnitine serves as a source of carnitine in the body, which regulates the production of energy from fats.

Additionally, clinical trials have also reported its benefit in reducing belly fat and enhancing cognition.

You can buy one bottle at a retail price of $80, and it contains 60 pills that will last a whole month.

2. Phen24 Appetite Suppressant

Phen24 bottles and capsules taken by MaxhealthLiving

Phen24 has a separate day and nighttime formula that promotes 24-hour weight loss.

The daytime formula contains ingredients that will put you in a happy mood, burn fat, reduce hunger, and recharge the body.

Whereas the nighttime formula releases stress suppresses cravings and promotes fat burning during sleep.

The key ingredients in the daytime formula are guarana, caffeine, cayenne pepper, and L-phenylalanine. Here, the guarana, caffeine, and cayenne powder all help to speed up the metabolism and burn calories.

Next on the list is L-phenylalanine which has been proven by clinical trials to boost mood and induce full body fat oxidation when taken pre-exercise.

The nighttime formula basically has glucomannan, Griffonia, choline bitartrate, and hops. All these ingredients are backed by scientific studies as follows;

  • A study on 214 overweight subjects showed that glucomannan reduces body weight and fat by improving lipid and glucose profiles, increasing metabolic rate, and reducing visceral fat.
  • A 4-week trial performed on 20 women showed that a compound in Griffonia increased the feeling of satiety in the experimental group and helped to reduce their BMI.
  • A study on athletes showed that choline promotes rapid reduction in body mass by reducing the hunger hormone, regulating fat metabolism, and converting it into energy.
  • A study performed on 30 adults showed that the hops significantly reduced cravings in the research group compared to the placebo.

You can purchase one box of Phen24 for $85. This box has a Phen24 day bottle containing 30 tablets and a Phen24 night bottle containing 60 pills, and it lasts a whole month.

Related: PhenQ Vs. Phen24

Bottom Line

To conclude, although Phentermine and Benzphetamine are quite similar in many aspects, Phentermine is the more popular weight loss drug due to multiple reasons.

On top is the reason that Phentermine has gathered more positive user reviews. However, it might be because it is more commonly prescribed than Benzphetamine.

But still, other points that make Phentermine the better obesity treatment is its lower risk of dependency and the higher efficacy of even a single dose regime.

Moreover, Phentermine can be prescribed in drug combinations that improve its tolerability and weight-reducing potential, but Benzphetamine has to be prescribed alone.

Nonetheless, both Benzphetamine and Phentermine pose similar risks to the cardiovascular system, hormonal system, digestive system, and central nervous system.

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