Prescription Appetite Suppressants: What are they and who uses them?

Around the world, 52% of adults over the age of 18 are overweight or obese. In the US those numbers are even higher with two in three adults tipping the scales into those ranges.

It’s no surprise, then, that weight loss solutions of all types have grown increasingly popular in recent years. For overweight patients, a typical weight loss regimen involves healthier eating and regular exercise.

However, when clinically obese patients need to lose some weight, the solution is often more complex. In the US, many doctors turn to prescription appetite suppressants to jumpstart their patients’ weight loss journey.

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Here we’ll give an overview of prescription appetite suppressants, who takes them and discuss a few popular pills. We’ll also discuss some alternatives to these medications.

What Are Prescription Appetite Suppressants?

Prescription appetite suppressants are medications that help you eat less. The goal of these medications is to make portion control easier and promote faster, easier weight loss. Since they are only available under prescription, a medical doctor must deem that you’re an appropriate candidate for the medication and write a script.

The majority of prescription appetite suppressants function as central nervous system (CNS) stimulants. They work by activating the part of your brain that is responsible for generating a “fight or flight” response when you’re stressed or in danger. In this heightened state, your heart races, appetite decreases and energy surges.

While these biological reactions initially developed to prepare us for survival in life-threatening situations (like fighting or evading a grizzly bear), 20th-century scientists discovered that continuously activating the CNS also promotes weight loss. So, prescription appetite suppressants trigger a response that imitates “fight or flight”  to help you eat less and move more on a daily basis. Fewer calories in and more calories out leads to weight loss.

Given these stimulant properties, prescription appetite suppressants are typically classified as controlled substances. Due to their addiction potential, most prescription appetite suppressants are class III or class IV controlled substances in the US.

Who Takes Prescription Appetite Suppressants?

Prescription appetite suppressants are designed as a short-term treatment for exogenous obesity. To understand this prescribing criteria we need to define obesity, and more specifically exogenous obesity.

A person is medically classified as obese if their body mass index (BMI) is greater than 30 kg/m2. BMI compares weight to height as a general estimation of weight status. It’s not perfect, but it’s widely-accepted as a reliable indicator of health status. Individuals with a BMI greater than 30 kg/m2 are classified as obese, and may be candidates for prescription appetite suppressants.

Exogenous obesity is obesity caused by consistently consuming more calories than you burn. More simply put, this is the type of obesity caused by eating too much and exercising too little. Exogenous obesity is distinct from endogenous obesity, which is caused by internal factors such as hormones or disease. People who carry extra weight due to hypothyroidism, for example, suffer from endogenous – not exogenous – obesity. Prescription appetite suppressants are designed to treat exogenous obesity because they help you eat less and move more to re-establish a healthier energy balance. They are not designed to address the underlying issues that cause endogenous obesity, and as such, should not be used treat it.

Some prescription appetite suppressants, such as phentermine, are also available for patients with a BMI ≥ 27 kg/m2 if they suffer from a condition that is worsened by being overweight. Relevant ailments include high blood pressure or type 2 diabetes. While patients with BMIs of 27-29.99 kg/m2 are only overweight (not obese), their existing conditions make weight loss more desirable from a medical perspective. These patients should also be evaluated to rule-out endogenous causes of extra weight.

In summary, prescription appetite suppressants are an option for otherwise-healthy patients with a:

  • BMI > 30 kg/m2
  • BMI ≥ 27 kg/m2 in the presence of a medical condition made worse by overweight status

Of course, a medical doctor is the only one who can decide if prescription appetite suppressants are right for you. These medications are contraindicated in the presence of several other medications, supplements and medical conditions. It is, therefore, vital that you remain open and honest with your doctor when discussing the possibility of prescription appetite suppressants.

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Common Prescription Appetite Suppressants

Now you know a little more about how prescription appetite suppressants work and who takes them, but we still haven’t told you which medications fall in this category. So, here’s three common prescription appetite suppressants!


Phentermine is the most-commonly prescribed appetite suppressant in the US. The active ingredient in this medication is phentermine HCL and it works as a CNS stimulant. Phentermine is only indicated for short-term use, so the typical prescription lasts about three months. This medicine comes as both capsules and tablets. Patients take phentermine 1-3x per day, depending on strength of each pill and overall daily dosage.

Popular brands of phentermine include Adipex (read more Adipex: The #1 Brand of Phentermine Weight Loss Pills), Duromine, Lomaira and Qsymia (a combination of phentermine + topiramate).


Phendimetrazine suppresses appetite and boosts appetite due to its main ingredient: phendimetrazine tartrate. Like other prescription appetite suppressants, it functions as a CNS stimulant. This medication is taken 1-3x per day depending on form and overall dosage. It comes in both capsule and tablet form, and should only be taken for a few weeks at a time.

Popular brands of phendimetrazine include Bontril, Adipost and Melfiat.


Similar to the medications listed above, diethylpropion works as a CNS stimulant to suppress appetite and boost energy. The active ingredient is diethylpropion hydrochloride. This medication can be take 1-3x per day, depending on each patient’s individual medication schedule. Diethylpropion is only indicated for short-term use (a few weeks) and should be discontinued earlier if it is not producing the desired results. It is only available in tablet form.

Popular brands of diethylpropion include Tenuate and Tepanil.

Alternatives to Prescription Appetite Suppressants

Prescription appetite suppressants are highly effective, but they’re not right for everyone. These medications carry the risk of serious side effects and cannot be taken in the presence of some medical conditions or other medicines/supplements. They’re also not right for someone who is just looking to slim down a little out of personal preference, not medical necessity.

So, what can you do if prescription appetite suppressants aren’t right for you?

If you’re severely obese, weight loss surgery may be another option. Curious about bariatric surgery? Speak with your doctor to learn more about if you’re a viable candidate.

If you’re only slightly overweight or already at a healthy weight, consider over-the-counter or natural appetite suppressants. Many supplement companies produce natural appetite suppressants that can help reduce cravings and boost weight loss. Some common foods and drinks, like cayenne peppers and coffee, also curb appetite naturally.

In Summary

Prescription appetite suppressants are medications that can help overweight and obese patients lose weight more easily. They work by targeting the central nervous system to stimulate a stress response that decreases appetite and boosts energy. Popular prescription appetite suppressants include phentermine, phendimetrazine and diethylpropion. However, while these medicines are highly effective, they’re safe or appropriate for everyone. Your doctor is the only one who can assess whether prescription appetite suppressants are right for you.

Your thoughts

What do you think? Would you consider prescription appetite suppressants to help jumpstart your weight loss? Share your thoughts with us in the comments section below!

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This article was contributed to by a guest author.


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