Duromine vs Panbesy: Which Is More Effective For Weight Loss?

Siena Team
17 Nov 2022

Fat burners, calorie cutters, and appetite suppressants are just a few of the common claims made by the many weight-loss supplements on the market. It makes sense if you are hesitant to try them, especially if you are unsure about their success rates and side effects.

Fortunately, there are several FDA-approved, scientifically-proven prescription medications that can improve your chances of dropping those pounds — and keeping them off. Among them are two brands that are available in Singapore, Duromine and Panbesy.

So, what are their differences and which is better for weight loss? Read on to find out.

What Are The Similarities Between Duromine and Panbesy?

Duromine and Panbesy contain the same active ingredient, phentermine. 

Phentermine is an anorectic agent (an agent that suppresses appetite). It works by stimulating the release of chemical messengers or neurotransmitters (i.e. norepinephrine, serotonin, and dopamineare) in the brain. With the increase in the levels of these chemicals in your brain, you feel full and therefore eat less. Over time, this can lead to weight loss, especially if accompanied by a proper diet and exercise.

Who Is Duromine/Panbesy Typically Prescribed To?

Like other prescription weight-loss drugs, Duromine/Panbesy is intended to be used as part of an overall weight-loss plan. Use of prescription weight-loss medications is typically reserved for people who:

  • Have a BMI of 30 or greater (severe obesity); or
  • Have a BMI of 27 or greater (moderate obesity) with the presence of a weight-related disease or complication such as Type 2 diabetes, high cholesterol, or high blood pressure

It is indicated for people who are obese, and who have failed to lose enough weight with diet and exercise alone — not for people who want to lose just a few pounds.

How Much Weight Can You Lose On Duromine/Panbesy?

Several clinical studies have shown that Duromine/Panbesy can support meaningful weight loss.

One small study from South Korea showed that almost 86% of people who were overweight or obese taking phentermine for 14 weeks lost more than 5% of their body weight. Another South Korean study looked specifically at people who have obesity (not overweight) and used phentermine for a 12-week course. It found that almost 96% of them lost more than 5% of their body weight, and 62% of the same group lost more than 10% of their body weight.

While Duromine/Panbesy is FDA-approved for short-term use of fewer than 12 weeks, healthcare professionals often prescribe phentermine off-label for longer use. Doctors may prescribe it intermittently, meaning you take a break from the medication for a set period of time before resuming it.

What Are The Side Effects Of Duromine/Panbesy?

The most commonly reported side effects of Duromine/Panbesy are:

  • dry mouth
  • insomnia
  • dizziness
  • heart palpitations
  • skin flushing
  • fatigue
  • constipation
  • irritability
  • nausea
  • vomiting

Just like all other medications, not everyone will experience side effects after taking Duromine/Panbesy. The severity of the side effects differs among individuals as well.

What Is The Difference Between Duromine and Panbesy?

The main difference lies in how phentermine is present in the two products.

Each Duromine capsule contains phentermine enclosed in a complex, released continuously over a 10 to 14 hour period. Meanwhile, phentermine in Panbesy exists as an ion and is absorbed over 3 to 4.4 hours.

There will be a longer-lasting and equal appetite suppression throughout the day with  Duromine as phentermine is released more slowly. On the other hand, all of the phentermine present in a Panbesy capsule is released at once and appetite suppression will subside gradually with time, therefore its effect is not as long-lasting.

Since phentermine is slowly absorbed into your bloodstream in smaller amounts after taking Duromine, the risk of side effects is lower. There will be higher levels of phentermine in the bloodstream initially with Panbesy as everything is released at once. This translates to a higher risk of side effects when taking Panbesy.

Which Is Better, Duromine vs Panbesy?

Ultimately, both medicines are approved for weight loss in obese people who have other risk factors like controlled hypertension. They are two of the most established weight loss pills frequently prescribed by doctors. Duromine and Panbesy, based on the same active ingredient used, have similar effectiveness – more than 5% body weight lost in 12 weeks on average.

If you are looking for a medicine that has a longer-lasting effect in curbing your appetite, Duromine is definitely the more outstanding candidate.

Where To Buy Duromine Or Panbesy In Singapore?

Being obese puts you at risk for more health complications, like diabetes and heart disease. When you don’t see the desired weight loss results despite efforts to change your diet or lifestyle, seeking professional help may be necessary as reducing the risk of more serious health complications as soon as possible is the top priority.

There are many websites selling Duromine, Panbesy and other anti-obesity medications which may not be scientifically proven to be safe or effective. However, do not fall into the trap of convenience of purchasing these medicines from unreliable sites and sellers! Remember that you can only obtain such medications if a qualified doctor prescribes them to you and you should only take them according to his instructions.

If you’re looking for convenience and getting approved medications for weight loss, turn to Siena instead! Gone are the days when you have to wait in line to visit the doctor. With us, you can speak to an SG-registered doctor about your weight loss issues online via a teleconsultation. We’ll deliver the medicines to your home if prescribed, in discreet packaging and at no additional cost. Simply complete this online questionnaire to get started today!


  • Ding H (2016). Modified-release drug products and drug devices. Shargel L, & Yu A.C.(Eds.), Applied Biopharmaceutics & Pharmacokinetics, 7e. McGraw Hill. Accessed December 17, 2021.
  • Kim, H. O., et al (2013, September). Postmarketing surveillance study of the efficacy and safety of phentermine in patients with obesity. Korean journal of family medicine, 34(5), 298–306. https://doi.org/10.4082/kjfm.2013.34.5.298 
  • MIMS. Phentermine: Indication, Dosage, Side Effect, Precaution.https://www.mims.com/singapore/drug/info/phentermine